Co-reporter:Xiaoli Sun;Jidong Zhang;Quan Li;Nan Gao;Xiaoqiu Yang;Zhongjie Ren
Langmuir April 26, 2016 Volume 32(Issue 16) pp:3983-3994
Publication Date(Web):2017-2-22
DOI:10.1021/acs.langmuir.6b00058
The crystalline morphology and orientation of poly(3-hydroxybutyrate) (PHB) thin film on the poly(vinylphenol) (PVPh) sublayer with different thickness was studied by atomic force microscopy, X-ray diffraction, and infrared spectroscopy. PVPh sublayer influences the morphology of PHB greatly. Although edge-on lamellae form on both Si and PVPh surfaces at relatively lower crystallization temperature, the morphology of them is quite different. It appears as sheaflike edge-on lamellar morphology on PVPh sublayer. In addition, the edge-on lamellae prefer to form on the PVPh sublayers at much higher crystallization temperature compared with that on Si wafer. The PVPh layer thickness also influences the crystalline morphology of PHB. On a 30 nm thick PVPh layer, sheaflike edge-on lamellae form in a wide range of crystallization temperatures. When the PVPh thickness increases to 65 nm, fingerlike morphology is observed when the crystallization temperature is lower than 95 °C. The fingerlike morphology is caused by a diffusion-limited aggregation process, and it requires an optimum condition. Thickness ratio between PHB and PVPh sublayer and temperature are two key factors for the formation of fingerlike morphology.
Co-reporter:Zhen Chen;Tingjie Zhang;Yi Zhang;Zhongjie Ren;Jianming Zhang
Polymer Chemistry (2010-Present) 2017 vol. 8(Issue 22) pp:3515-3522
Publication Date(Web):2017/06/06
DOI:10.1039/C7PY00418D
A main chain donor–acceptor copolysiloxane named poly(N,N′-bis(dimethylsiloxane)propyl tetrachloro perylene tetracarboxylic acid diimide-alt-bis(dimethylsiloxane)-2,2′:5′,2′′-terthiophene) (PBIClSi-alt-PTSi) was successfully synthesized, in which terthiophene donors and perylenediimide acceptors are connected with siloxanes. PBIClSi-alt-PTSi displays high thermal stability, which ensures its long-term stability for device operation. The calculated HOMO and LUMO energy levels of PBIClSi-alt-PTSi are mainly located on terthiophene and perylenediimide moieties, respectively. A fabricated memory device with the configuration of ITO/PBIClSi-alt-PTSi/Au(Al) shows nonvolatile write-once-read many-times (WORM) memory characteristics. Its turn-on threshold voltage is quite low (ca. 1.0 V), meanwhile the on/off current density ratio is around 6 × 103 under ambient atmosphere. As far as we know, this is the first example of a main chain donor–acceptor copolysiloxane used as a memory device. And the low turn-on threshold voltage of 1.0 V may be caused by the high flexibility of Si–O–Si. Furthermore, the progression of the ITO/PBIClSi-alt-PTSi/Au device from a low to high conductivity state is detected by current sensing atomic force microscopy for the first time. At the threshold voltage, the topology of the PBIClSi-alt-PTSi films displays an obvious change due to the arrangement of molecular chains.
Co-reporter:Danyang Ma, Shiyu Feng, Jicheng Zhang, Chun Kou, Xue Gong, Qiaosheng Li, Xinjun Xu, Shouke Yan, Zhishan Bo
Dyes and Pigments 2017 Volume 146(Volume 146) pp:
Publication Date(Web):1 November 2017
DOI:10.1016/j.dyepig.2017.07.014
•Two non-fullerene small molecular acceptors with a carbazole core were synthesized.•Effects of different side chains on the device performance of non-fullerene acceptors have been investigated.•A high open circuit voltage about 1 V can be achieved in devices based on these two acceptors.•OSCs based on carbazole-cored acceptors exhibit a good performance even though the ΔELUMO and ΔEHOMO are both small.Two novel carbazole-cored small molecules CzC6C8 and CzC8 bearing different side chains and two 3-ethylrhodanine end-capping groups were synthesized and used as electron acceptors in organic solar cells (OSCs). Devices based on these two acceptors showed a high open circuit voltage (Voc) about 1 V. Due to more closely molecular stacking and improved film morphology, CzC8 bearing a linear alkyl side chain showed a better photovoltaic performance than CzC6C8 bearing a branched one. CzC8 based OSCs can still exhibit a good performance even though the ΔELUMO and ΔEHOMO between donor and acceptor are both small. Three polymer donors (PBT, PTB7-Th, and PTFBDT) with a similar LUMO level but various HOMO levels were tested and they all showed good PCE values larger than 4.6%. Among them, PTB7-Th:CzC8 based devices afforded the highest PCE of 4.91% and PTFBDT:CzC8 based ones gave the highest Voc of 1.16 V.
Co-reporter:Chensen Li;Roberto S. Nobuyasu;Yukun Wang;Ferno B. Dias;Zhongjie Ren;Martin R. Bryce
Advanced Optical Materials 2017 Volume 5(Issue 20) pp:
Publication Date(Web):2017/10/01
DOI:10.1002/adom.201700435
AbstractThermally activated delayed fluorescence (TADF) white organic light-emitting diodes (WOLEDs) have drawn tremendous interest and have been extensively studied because of harvesting both triplet and singlet excitons without heavy metals. However, single white-light-emitting polymers are currently limited and few strategies exist to design these materials. Herein, a new strategy is proposed to develop the polymers with tunable emission colors by combining fluorescence and TADF based on aggregation-enhanced emission (AEE) characteristics. The polymers containing different ratios of pendant 2-(10H-phenothiazin-10-yl)dibenzothiophene-S,S-dioxide units with yellow TADF emission and dibenzothiophene units with blue fluorophor emission, which display both TADF and AEE characteristics, are synthesized successfully. Among them, the emission color of P3 in different tetrahydrofuran/water mixtures changes from greenish-blue to white or yellow. Moreover, P3 displays white emission in the solid state dispersing by poly(methyl methacrylate). In addition, electroluminescent device of P3 achieve white light emission with high color rending indexes (CRI) and low turn-on voltages (V on ). P3 OLEDs show two-color warm-white emission with high CRI of 77, low V on of 2.9 V, CEmax of 23.0 cd A−1, PEmax of 32.8 lm W−1, external quantum efficiency (EQE)max of 10.4% with Commission Internationale de l'Eclairage coordinates of (0.37, 0.38) at 5 V. Moreover, EQE of 2.6%, CE of 5.7 cd/A, PE of 4.7 lm W−1 at 100 cd m−2 are obtained. To the best of our knowledge, this work reports the first example of warm-white TADF polymer OLEDs.
Co-reporter:Zhongjie Ren, Shouke Yan
Progress in Materials Science 2016 Volume 83() pp:383-416
Publication Date(Web):October 2016
DOI:10.1016/j.pmatsci.2016.07.004
During the past few years, polysiloxanes have been extensively researched on optimizing the physical and electronic properties of organic polymer semiconductors. Polysiloxanes display their advantages including good solubility in common organic solvents, good film-forming ability, fair adhesion to various substrates and excellent resistance to thermal, chemical and irradiation degradations. In this review, we focus on the fundamental design and synthesis strategies of bonding polysiloxanes with organoelectronic groups. The characterization of polysiloxanes will be briefly introduced. Specifically, we summarize the recent advances of the utilization of polysiloxanes as organic light-emitting diodes (OLEDs), solar cells, electrical memories and liquid crystalline materials. Finally, several perspectives related to polysiloxanes materials for organoelectronic applications are proposed based on the reported progress and our own opinion.
Co-reporter:E Wang, Dianming Sun, Huihui Li, Xiaoli Sun, Junteng Liu, Zhongjie Ren and Shouke Yan
Journal of Materials Chemistry A 2016 vol. 4(Issue 28) pp:6756-6760
Publication Date(Web):28 Jun 2016
DOI:10.1039/C6TC01892K
Trinitrotoluene (TNT) and dinitrotoluene (DNT) as the most common explosives are considered to be harmful to the environment and humans. Therefore, the detection of these explosives has been attracting more and more attention. And easily prepared polymer materials with high sensing performance are still in demand. In this study, two silicon-containing polymers, PCzSiO and PCzSiPh, are employed to detect the explosives TNT and DNT. PCzSiPh shows a better performance and the quenching efficiency of PCzSiPh films in TNT and DNT vapor can reach 91.0 ± 0.3% and 94.4 ± 0.3%, respectively, due to their loose molecular chain structure. Furthermore, the fluorescence quenching of PCzSiPh in TNT and DNT is little dependent on the thickness of the film. And the PCzSiPh films show good reversibility, good film-forming ability and high thermal and morphological stability, which suggest their potential application in the coating of detection devices.
Co-reporter:Ce Mi, Jiandong Zhou, Zhongjie Ren, Huihui Li, Xiaoli Sun and Shouke Yan
Polymer Chemistry 2016 vol. 7(Issue 2) pp:410-417
Publication Date(Web):13 Nov 2015
DOI:10.1039/C5PY01532D
PBA nanotubes with different diameters have been prepared. The crystallization behavior and phase transition behavior have been explored by using X-ray diffraction and DSC. For isothermal melt crystallization, the temperature dependence of the crystal phase and the orientation of PBA crystals in the Anodic Alumina Oxide (AAO) templates are very different from that of the bulk. In the AAO templates, especially in the narrow nanopores, the b-axis of the α phase prefers to adopt the orientation parallel to the long axis of the pore. In addition, an in situ X-ray experiment indicates that some molecular chains cannot pack into the crystal lattice in the AAO template at high crystallization temperature, and they are able to crystallize only after cooling back to room temperature. The core–shell structure of PBA exists in the AAO template, which leads to the incomplete crystallization of the α form at higher crystallization temperature and the formation of β-crystals in the cooled sample. The phase transition behavior of β-crystals in the heating process is also affected by nanoporous confinement. The expansion of the β-crystal unit cell is depressed and the phase transition behavior of β to α is altered in the AAO template. At a slow heating rate, compared to the β-PBA in bulk, β-crystals transit to α-crystals at a slower rate in the templates. At a fast heating rate, less β-crystals transit to α-crystals and more β-crystals prefer to melt directly in the AAO templates.
Co-reporter:Liguo Chai, Xiao Liu, Xiaoli Sun, Lin Li and Shouke Yan
Polymer Chemistry 2016 vol. 7(Issue 10) pp:1892-1898
Publication Date(Web):25 Jan 2016
DOI:10.1039/C5PY02037A
The melting of PEO single crystals placed on an Si wafer and PVPh thin films with different thicknesses was studied. The results show that PEO/substrate interactions have a pronounced influence on the melting temperature of the PEO single crystals and spreading behaviour of the PEO melts. The melting point of the PEO single crystals placed on the PVPh sublayer depends on the thickness of the PVPh layer. A melting point depression of the PEO single crystal was observed with increasing PVPh layer thickness. This has been correlated to the enhanced interaction between PEO and PVPh based on hydrogen bonding. It is speculated that the thickening of the PVPh layer is in favor of the formation of hydrogen bonds between PVPh and PEO due to the increased amount of exposed hydroxyl groups of PVPh and their ability to build hydrogen bonds with the oxygen groups of PEO.
Co-reporter:Xiaoli Sun, Qunqun Fang, Huihui Li, Zhongjie Ren, and Shouke Yan
Langmuir 2016 Volume 32(Issue 13) pp:3269-3275
Publication Date(Web):March 23, 2016
DOI:10.1021/acs.langmuir.6b00251
Poly(butylene adipate) (PBA) was infiltrated into the anodic alumina oxide (AAO) templates with the pore diameter of around 30, 70, and 100 nm and PBA nanotubes with different diameters were prepared. The crystallization and phase transition behavior of the obtained PBA nanotubes capped in the nanopores have been explored by using X-ray diffraction and differential scanning calorimetry. Only α-PBA crystals form in the bulk sample during nonisothermal crystallization. By contrast, predominant β-PBA crystals form in the AAO templates. The β-PBA crystals formed in the nanopores with pore diameter less than 70 nm prefer to adopt an orientation with their b-axis parallel to the long axis of the pore. During the melt recrystallization, it was found that the critical temperature (Tβ), below which pure β-crystals form, is 20 °C for bulk PBA. It drops down significantly with the pore diameter for the PBA in the AAO template. Moreover, the β-crystals in the porous template exhibit larger lattice parameters compared with the bulk crystals. By monitoring the change of β-crystals in the heating process, it was found that β-crystals in the AAO template with the pore diameter of 30 nm (D30) melt directly while the β-crystals transform to α-crystals in the template with the pore diameter of 100 nm (D100). The intensity of (020) Bragg peak of β-crystals decreases at a similar rate in both D30 and D100 but disappears at a relatively lower temperature in D30. On the other hand, the β(110) peak intensity of β-PBA crystals formed in the D100 template decreases first at slower rate before α crystals appear, and then at a faster rate once the β to α phase transition takes place.
Co-reporter:Xiying Dai, Jiali Niu, Zhongjie Ren, Xiaoli Sun, and Shouke Yan
The Journal of Physical Chemistry B 2016 Volume 120(Issue 4) pp:843-850
Publication Date(Web):January 8, 2016
DOI:10.1021/acs.jpcb.5b11178
Poly(vinylidene fluoride) (PVDF) nanotubes were fabricated by melt-wetting into porous anodic aluminum oxide (AAO) templates with two different interfacial properties: one is pristine AAO, and the other is modified by FOTS (AAO-F). Their crystallization and melting behaviors are compared with those of a bulk sample. For the PVDF in AAO-F, the nonisothermal crystallization temperature is slightly lower than that of bulk, and the melting temperature is similar to that of bulk. For the PVDF in pristine AAO, when the pore diameter is 200 nm, the crystallization is induced by two kinds of nucleation: heterogeneous nucleation and interface-induced nucleation. On the contrary, in the AAO template with pore diameter smaller than 200 nm, only interface-induced nucleation occurs. The melting temperature of PVDF crystals in the pristine AAO is much higher than that of bulk which can be attributed to the presence of an interfacial layer of PVDF on the template inner surface. The interaction between PVDF and AAO template produces the interfacial layer. Such an interfacial layer plays an important role in enhancing the melting temperature of PVDF crystals. The higher melting peak is always observed when the PVDF is nonisothermally crystallized in the AAO template irrespective of the thermal erasing temperature suggesting the interfacial layer is very stable on the AAO template surface. If the PVDF nanostructures are released from AAO template, the higher melting peak disappears with the enhancement of thermal erasing temperature.
Co-reporter:Chunyue Hou, Tianbo Yang, Xiaoli Sun, Zhongjie Ren, Huihui Li, and Shouke Yan
The Journal of Physical Chemistry B 2016 Volume 120(Issue 1) pp:222-230
Publication Date(Web):December 29, 2015
DOI:10.1021/acs.jpcb.5b09960
The chain organization of poly(ε-caprolactone) (PCL) in its blend with poly(4-hydroxystyrene) (PVPh) in thin films (130 ± 10 nm) has been revealed by grazing incident infrared (GIIR) spectroscopy. It can be found that PCL chains orient preferentially in the surface-normal direction and crystallization occurs simultaneously. The morphology of the PCL/PVPh blends films can be identified by optical microscopy (OM). When crystallized at 35 °C, the blends film shows a seaweed-like structure and becomes more open with increasing PVPh content. In contrast, when crystallized at higher temperatures, i.e., 40 and 45 °C, dendrites with apparent crystallographically favored branches can be observed. This characteristic morphology indicates that the diffusion-limited aggregation (DLA) process controls the crystal growth in the blends films. The detailed lamellar structure can be revealed by the height images of atomic force microscopy (AFM), i.e., the crystalline branches are composed of overlayered flat-on lamellae. The branch width has been found to be dependent on the supercooling and PVPh content. This result differs greatly from pure PCL, in which case the crystal patterns controlled by DLA process developed in ultrathin film or monolayers of several nanometers. In the PCL/PVPh blends case, the strong intermolecular interactions and the dilution effect of PVPh should contribute to these results. That is to say, the mobility of PCL chains can be retarded and diffusion of them to the crystal growth front slows down greatly, even though the film thickness is far more than the lamellar thickness of PCL.
Co-reporter:Xiaoli Sun, Tiantian Gao, Shuyang Wang, Shujing Zhang, Ce Mi, Huihui Li, Shouke Yan
Polymer 2016 Volume 105() pp:431-439
Publication Date(Web):22 November 2016
DOI:10.1016/j.polymer.2016.06.052
•The effect of deformation rate and temperature on the crystal-crystal transition of sPP is studied.•At lower stretching temperature, phase transition behavior is determined by temperature and deformation rate.•At 90 °C, form I transits to form III and the transition process does not depend on the deformation rate.The effect of deformation rate and temperature on the crystal−crystal transition of sPP with [rrrr] = 78% was studied by wide-angle X-ray diffraction measurements, using synchrotron radiation. Three stretching temperatures (25, 40, 90 °C) and two different deformation rates (10 and 20 mm/min) were selected. At lower stretching temperature (e.g. 25 °C), the transformation of form I to mesomorphic phase occurs at both deformation rates. Lower deformation rate favors the occurrence of transition at lower strain. By contrast, higher deformation rate can speed up the transition process, although the start of transformation is observed at higher strain. At the stretching temperature of 40 °C, form I transits to mesomorphic phase at lower deformation rate. At higher deformation rate, the transformation of form I to form III through mesomorphic phase is evidenced. At the stretching temperature of 90 °C, the form I transits to form III and it does not depend on the deformation rate. From the results of stress-strain curves, it can be known that the phase transition from form I into mesomorphic phase is neither strain-induced nor stress-induced transition. These results indicate that the structural evolution of sPP with [rrrr] = 78% in the stretching process strongly depends on the deformation rate and temperature.
Co-reporter:Zhongjie Ren, Roberto S. Nobuyasu, Fernando B. Dias, Andrew P. Monkman, Shouke Yan, and Martin R. Bryce
Macromolecules 2016 Volume 49(Issue 15) pp:5452-5460
Publication Date(Web):July 27, 2016
DOI:10.1021/acs.macromol.6b01216
Materials that display thermally activated delayed fluorescence (TADF) have recently been identified as the third generation emitters for organic light-emitting diodes (OLEDs). However, there are only a few reported examples of polymeric TADF materials. This study reports a series of polymers with an insulating backbone and varying ratios of 2-(10H-phenothiazin-10-yl)dibenzothiophene-S,S-dioxide as a pendant TADF unit. Steady-state and time-resolved fluorescence spectroscopic data confirm the efficient TADF properties of the polymers. Styrene, as a comonomer, is shown to be a good dispersing unit for the TADF groups, by greatly suppressing the internal conversion and triplet–triplet annihilation. Increasing the styrene content within the copolymers results in relatively high triplet energy, small energy splitting between the singlet and triplet states (ΔEST), and a strong contribution from delayed fluorescence to the overall emission. Green emitting OLED devices employing these polymers as spin-coated emitting layers give high performance, which is dramatically enhanced in the copolymers compared to the homopolymer. Within the series, Copo1 with a regiorandom ratio of 37% TADF units:63% styrene units displays the best performance with a maximum external quantum efficiency (EQE) of 20.1% and EQE at 100 cd m–2 of 5.3%.
Co-reporter:Hong Yao;Jia-li Niu;Jie Zhang;Nan-ying Ning
Chinese Journal of Polymer Science 2016 Volume 34( Issue 7) pp:820-829
Publication Date(Web):2016 July
DOI:10.1007/s10118-016-1794-4
The mechanical properties and phase morphologies of cis-1,4-butadiene rubber (BR) blended with polyethylene (PE) at different blend ratios were studied. The tensile test results show that the PE exhibits excellent reinforcing capabilities towards BR. Blending BR with PE results in a remarkable enhancement of tensile strength, modulus and the elongation at break simultaneously. An increment of tensile strength from 1.11 MPa to 16.26 MPa was achieved by incorporation of 40 wt% PE in the blends. The modulus and elongation at break of 40/60 PE/BR blends are also about 5 times higher than those of the pure BR treated under exactly the same conditions. The tear test indicates that the tear strength also increases with the increase of PE content. It reaches 58.38 MPa for the 40/60 PE/BR blend, which is approximately 10 times higher than that of the pure BR. Morphological study demonstrates that the PE forms elongated microdomains finely dispersed in the BR matrix when its content is over 30 wt%, which corresponds to the remarkably enhanced mechanical properties. According to the results, reinforcement mechanism of PE toward BR dependent on the microstructure has been discussed and two different mechanisms have been proposed.
Co-reporter:Li-guo Chai;Hai-xin Zhou;Xiao-li Sun;Hui-hui Li
Chinese Journal of Polymer Science 2016 Volume 34( Issue 4) pp:513-522
Publication Date(Web):2016 April
DOI:10.1007/s10118-016-1770-z
Oriented thin films of P3HT were obtained by a friction-transfer technique. The morphology and structure of the film were studied by means of optical microscopy, atomic force microscopy and transmission electron microscopy. Optical microscopy observation indicates that large size well-ordered P3HT thin films can be produced by a friction-transfer technique. Highly ordered lamellae were observed in P3HT friction-transferred films by electron microscopy. Electron diffraction results confirm the existence of high orientation with the a- and c-axes of P3HT crystals aligned in the film plane while the c-axis parallel to the friction-transfer direction. The atomic force microscopy observation of the as-prepared P3HT thin film shows, however, a featureless top surface morphology, indicating the structure inhomogeneity of the obtained film. To get highly oriented P3HT thin films with homogenous structure, high temperature annealing, solvent vapor annealing and self-seeding recrystallization of the friction-transferred film were performed. It is confirmed that solvent vapor annealing and self-seeding recrystallization methods are efficient in improving the surface morphology and structure of the frictiontransferred P3HT thin film. Highly oriented P3HT films with unique structure can be obtained through friction-transfer with subsequent solvent vapor annealing and self-seeding recrystallization.
Co-reporter:Bing He, Zhongjie Ren, Chenze Qi, Shouke Yan and Zhaohui Wang
Journal of Materials Chemistry A 2015 vol. 3(Issue 24) pp:6172-6177
Publication Date(Web):14 May 2015
DOI:10.1039/C5TC01046B
A one-step synthesis of a large-area and highly nitrogen-doped graphene (NG) membrane with few defects derived from poly 4-vinyl pyridine (P4VP) has been reported. The synthesis temperature has been optimized by Raman spectroscopy and X-ray photoelectron spectroscopy (XPS). With this approach, a large-area of more than 80% single-layer NG membrane with a nitrogen content of 6.37% can be obtained. Scanning electron microscopy (SEM), atomic force microscopy (AFM), Raman mapping-mode, optical microscopy (OM) and transmission electron microscopy (TEM) analyses reveal that the resultant NG is a flat, continuous, uniform and monolayered graphene membrane with a large area and a well-ordered crystalline structure. The electrical measurement confirms the typical n-type field-effect transistors (FETs) for NG both in air and vacuum, and the electron mobility can reach as high as 365 cm2 V−1 s−1, much higher than those of NGs previously reported. In addition, the transmittance and sheet resistance of NG correlates well with a monolayered structure and semiconducting properties, which also makes it a candidate of transparent electrode for various optoelectronic devices.
Co-reporter:Dianming Sun, Zhongjie Ren, Martin R. Bryce and Shouke Yan
Journal of Materials Chemistry A 2015 vol. 3(Issue 37) pp:9496-9508
Publication Date(Web):14 Aug 2015
DOI:10.1039/C5TC01638J
Organic light emitting diodes (OLEDs) are currently receiving much attention for applications in new generation full-colour flat-panel and flexible displays and as sources for low energy solid-state lighting. Arylsilanes and siloxanes have been extensively studied as components of OLEDs, mainly focusing on optimizing the physical and electronic properties of the light-emitting layer and other functional layers within the OLED architecture. Arylsilanes and siloxanes display the advantages of good solubility in common organic solvents and excellent resistance to thermal, chemical and irradiation degradations. In this review, we summarize the recent advances in the utilization of arylsilanes and siloxanes as fluorophore emitters, hosts for phosphor emitters, hole and exciton blocking materials, and as electron and hole transporting materials. Finally, perspectives and challenges related to arylsilanes and siloxanes for OLED applications are proposed based on the reported progress and our own opinions.
Co-reporter:Ce Mi, Ruize Tan, Dianming Sun, Zhongjie Ren, Xiaoli Sun and Shouke Yan
Journal of Materials Chemistry A 2015 vol. 3(Issue 39) pp:10249-10255
Publication Date(Web):18 Sep 2015
DOI:10.1039/C5TC02195B
In this study, two new donor–acceptor alternate copolysiloxanes containing carbazole and PDI derivatives pendants (PCzMSi-alt-PDISi and PCzPhSi-alt-PDISi) were prepared. The two copolysiloxanes showed the resistor type memory behavior. The memory devices based on PCzMSi-alt-PDISi and PCzPhSi-alt-PDISi exhibited nonvolatile flash memory characteristics, with an ON/OFF current density ratio of 103 and low threshold voltages (less than 1 V). As far as we know, it is the first nonvolatile flash memory device reported with the lowest threshold voltage based on the copolymer due to high flexibility of Si–O bonds. The conformation change from the regiorandom and regioregular alignments and the charge transfer interactions between pendent carbazole donor and PDI acceptor moieties as well as the unstable CT complex explain their memory characteristics. Our results open a new way to prepare the low-energy cost flash memory devices with the donor–acceptor pendent polysiloxanes.
Co-reporter:Dianming Sun, Xiaokang Zhou, Junteng Liu, Xiaoli Sun, Huihui Li, Zhongjie Ren, Dongge Ma, Martin R. Bryce, and Shouke Yan
ACS Applied Materials & Interfaces 2015 Volume 7(Issue 51) pp:27989
Publication Date(Web):February 4, 2015
DOI:10.1021/am507592s
The synthesis and characterization is reported of an efficient polysiloxane derivative containing the 1,3-bis(9-carbazolyl)benzene (mCP) moiety as a pendant unit on the polysiloxane backbone. In comparison with mCP, the mCP-polysiloxane hybrid (PmCPSi) has significantly improved thermal and morphological stabilities with a high decomposition temperature (Td = 523 °C) and glass transition temperature (Tg = 194 °C). The silicon–oxygen linkage of PmCPSi prevents intermolecular π-stacking and ensures a high triplet energy level (ET = 3.0 eV). Using PmCPSi as a host, blue phosphorescent organic light emitting devices (PhOLEDs) effectively confine triplet excitons, with efficient energy transfer to the guest emitter and a relatively low turn-on voltage of 5.8 V. A maximum external quantum efficiency of 9.24% and maximum current efficiency of 18.93 cd/A are obtained. These values are higher than for directly analogous poly(vinylcarbazole) (PVK) based devices (6.76%, 12.29 cd/A). Good color stability over a range of operating voltages is observed. A two-component “warm-white” device with a maximum current efficiency of 10.4 cd/A is obtained using a blend of blue and orange phosphorescent emitters as dopants in PmCPSi host. These results demonstrate that well-designed polysiloxane derivatives are highly efficient hosts suitable for low-cost solution-processed PhOLEDs.Keywords: FIrpic; high triplet energy; orange phosphor; phosphorescent organic light-emitting diode; polymeric host; polysiloxane
Co-reporter:Dianming Sun, Xiaokang Zhou, Huihui Li, Xiaoli Sun, Zhongjie Ren, Dongge Ma, and Shouke Yan
ACS Applied Materials & Interfaces 2015 Volume 7(Issue 32) pp:17802
Publication Date(Web):August 7, 2015
DOI:10.1021/acsami.5b04112
A series of 3,3′-bicarbazole (mCP)-functionalized tetraphenylsilane derivatives (SimCPx), including bis(3,5-di(9H-carbazol-9-yl)phenyl)diphenylsilane (SimCP2), tris(3,5-di(9H-carbazol-9-yl)phenyl)methylsilane (SimCP3-CH3), tris(3,5-di(9H-carbazol-9-yl)phenyl)phenylsilane (SimCP3-Ph), and tetrakis(3,5-di(9H-carbazol-9-yl)phenyl)silane (SimCP4), serving as bipolar blue hosts for bis[2-(4,6-difluorophenyl)pyridyl-N,C2′]iridium(III) (FIrpic), have been synthesized by incorporating different ratios of mCP subunits into a central silicon atom. All of the SimCPx derivatives have wide bandgaps and high triplet energies because of the indirect linkage by silicon between each mCP subunit. The good solubility and high thermal and morphological stability of SimCPx are beneficial for forming amorphous and homogeneous films through solution processing. Density functional theory simulations manifest the better bipolar characteristics for SimCPx using three and four mCP units rather than the represented bipolar host SimCP2. As a result, SimCP4 presents the best electron-transporting ability for charge balance. Consequently, the lowest driving voltage of 4.8 eV, and the favorable maximum efficiencies of 14.2% for external quantum efficiency (28.4 cd A–1, 13.5 lm W–1), are achieved by solution-processed, SimCP4-based blue phosphorescent organic light-emitting diodes as the highest performance among SimCPx, in which 32% improved device efficiencies compared to that of SimCP2 are obtained. It is inspiring to develop efficient bipolar hosts for blue phosphors by just incorporating monopolar carbazole into arylsilanes in two steps.Keywords: bipolar host; blue phosphorescent OLEDs; carbazole; small molecule host materials; tetraphenylsilane
Co-reporter:Yang Dong, Zhaomin Yang, Zhongjie Ren and Shouke Yan
Polymer Chemistry 2015 vol. 6(Issue 45) pp:7827-7832
Publication Date(Web):24 Sep 2015
DOI:10.1039/C5PY00992H
In this work, pyrene as a pendent is attached to the polysiloxane chain via the Heck coupling reaction to obtain a pyrene based polysiloxane (PySQ). The PySQ exhibits a high decomposition temperature (Td = 343 °C) and glass transition temperature (Tg = 167 °C). The introduction of polysiloxane reduces the aggregation of pyrene obviously. Moreover, the prepared PySQ shows aggregation induced enhanced emission (AIEE), which is favorable for the photoluminescence of pyrene. Molecular simulation and cyclic voltammetry reveal that the introduction of polysiloxanes doesn't affect the photophysical and electrochemical properties of pyrene. In addition, the AIEE effect endows PySQ with a longer photoluminescence lifetime as determined by transient photoluminescence decay measurements.
Co-reporter:Liwei Ye, Huihui Li, Zhaobin Qiu and Shouke Yan
Physical Chemistry Chemical Physics 2015 vol. 17(Issue 11) pp:7576-7580
Publication Date(Web):13 Feb 2015
DOI:10.1039/C4CP05910G
The melt–recrystallization behavior of α-iPP fibers embedded in an amorphous HIPS matrix has been studied by means of optical microscopy. The amorphous HIPS serving as a supporter of iPP fibers does not become involved in the nucleation and crystallization process of the molten highly oriented iPP fibers. It also does not provide any birefringence under the optical microscope with crossed polarizers. This enables the study of orientation-induced β-iPP crystallization through a control of the melting status of the fibers. Through melting the fibers at different temperatures above 175 °C and subsequent recrystallization, some β-iPP crystals were always produced. The content of the β-iPP crystal depends strongly on the melting temperature and melting time of the iPP fibers. It was confirmed that melting the iPP fibers at relatively lower temperature, e.g. 176 °C, less amount of β-iPP crystals were observed. The content of β-iPP crystal enhances first with increasing melting temperature and then decreases with further increase of the fiber melting temperature. The β-iPP crystallization is found to be most favorable upon melting the fibers at 178 °C for 2 min. This demonstrates the requirement of a certain chain or chain segment orientation for generating β-iPP crystallization on the one hand, while higher orientation of the iPP chains or chain segments encourages the growth of iPP crystals in the α-form on the other hand. This has been further confirmed by varying the melting time of the fiber at different temperatures, since relaxation of the iPP molecular chains at a fixed temperature is time dependent. Moreover, the complete transformation of α-iPP fibers in some local places into β-iPP crystals implies that the αβ-transition may not be required for the orientation-induced β-iPP crystallization.
Co-reporter:Tingjie Zhang, Zhongjie Ren, Xiaoli Sun and Shouke Yan
Physical Chemistry Chemical Physics 2015 vol. 17(Issue 35) pp:23069-23073
Publication Date(Web):14 Aug 2015
DOI:10.1039/C5CP04228C
Perylenebisimide (PBI) nanowires and nanosheets with high chemical and mechanical stability are prepared by a simple way. Firstly, a PBI-based organosilane precursor PBI-Si(OEt)3 was synthesized. Its nanostructures were then assembled by a solvent-exchange method. The nanostructures could be adjusted by assembling in different solvents. The obtained nanostructures were finally fixed by acetic acid vapor treatment through polycondensation of the triethoxysilyl groups in the precursors. After polycondensation, the nanostructures hardly change and they become insoluble in common solvents. Moreover, the conductivity of the polycondensed nanowires and nanosheets are ca. 35–40 times than that of polycondensed spin-coated PBI-Si(OEt)3 film by current sensing atomic force microscopy (CSAFM).
Co-reporter:Shujing Zhang, Xiaoli Sun, Zhongjie Ren, Huihui Li and Shouke Yan
Physical Chemistry Chemical Physics 2015 vol. 17(Issue 48) pp:32225-32231
Publication Date(Web):18 Nov 2015
DOI:10.1039/C5CP06076A
The miscibility of poly(propylene carbonate) (PPC) and poly(3-hydroxybutyrate) (PHB) blends was analyzed by differential scanning calorimetry (DSC) and polarized optical microscopy (POM). The results indicated that the blends are immiscible at most blending compositions, and a miscible blend can be obtained when the PHB content is as low as 10 wt%. The morphology of the PPC/PHB (70/30) blend film was characterized by POM, scanning electron micrography (SEM) and Fourier transform infrared spectroscopy (FTIR), and the development of a PPC-top and microporous PHB-bottom bilayer structure can be revealed. Different from the normal case, phase separation can take place on the normal direction of the film surface in the PPC/PHB (70/30) blend at 190 °C, attributed to the different surface energies of the two components. The continuous segregation of PPC to the top-layer can result in the crystallization of PHB at the bottom layer and conversely promote the complete development of a bilayer structure. Since the isotropic PPC layer is transparent with no birefringence, the PHB spherulite with a microporous structure at the bottom layer can be observed directly by POM. Moreover, the microporous structure of the bottom layer should be attributed to the solution cast procedure. Thus, some unique crystalline patterns may be created in the demixed crystalline/amorphous polymer blends, which differ greatly from those obtained from the miscible blend systems.
Co-reporter:Hong Yao;Jun-teng Liu;Li-qun Zhang;Shou-ke Yan 闫寿科
Chinese Journal of Polymer Science 2015 Volume 33( Issue 3) pp:386-394
Publication Date(Web):2015 March
DOI:10.1007/s10118-015-1592-4
Phase structure and crystallization behavior of polyethylene (PE) in its blends with cis-1,4-butadiene rubber (BR) at different blend ratios and sample preparation conditions were studied. The PE is finely dispersed in the BR matrix. For samples hot pressed at 145 °C, circular PE microdomains with randomly oriented PE lamellar aggregates were produced. The domain size and number increase with increasing PE content. When the PE content is over 10 wt%, most of the PE domains impinged each other. The separated PE domains are connected by PE stripes with parallel arranged lamellar aggregates. For samples hot pressed at 140 °C, elongated PE microdomains with oriented PE lamellar aggregates were obtained due to the shear flow. The crystallization of PE in the blends depends on the phase structure. Confined crystallization of PE occurs in small microdomains at relatively low temperature. With the increase of domain size, the crystallization ability of PE increases while the confined crystallization decreases.
Co-reporter:Guanyin Wen;Zhongjie Ren;Dianming Sun;Tingjie Zhang;Lili Liu
Advanced Functional Materials 2014 Volume 24( Issue 22) pp:3446-3455
Publication Date(Web):
DOI:10.1002/adfm.201304004
Alternating copolysiloxane with both electron donor terthiophene and electron acceptor perylenediimide derivative pendants (PTSi-alt-PDISi) is synthesized successfully. The polymer exhibits high decomposition and glass transition temperatures, good film-forming ability, and high morphological stability. The estimated HOMO and LUMO energy levels of PTSi-alt-PDISi are –5.77 and –3.90 eV, respectively. The fabricated memory device with the configuration of ITO/PTSi-alt-PDISi/Au(Al) shows nonvolatile write-once-read-many-times (WORM) memory characteristics. Its turn-on threshold voltage is 1.7 V, while its ON/OFF current density ratio is around 104 in ambient atmosphere. The well-defined memory property of PTSi-alt-PDISi is attributed to the transition of the pendant terthiophene and perylenediimide groups from the disoriented state to the ordered face-to-face conformation at the threshold voltage and the charge transfer interaction between pendent terthiophene donor and perylenediimide acceptor moieties, which are confirmed by XRD patterns and fluorescence emission measurement. This suggests that the new donor–acceptor polysiloxanes have potential applications in the field of memory devices.
Co-reporter:Dianming Sun, Yongxiu Li, Zhongjie Ren, Martin R. Bryce, Huihui Li and Shouke Yan
Chemical Science 2014 vol. 5(Issue 8) pp:3240-3245
Publication Date(Web):13 Jun 2014
DOI:10.1039/C4SC01068J
Electrochemical polymerization of 3-methylthiophene on highly oriented poly(vinylidene fluoride) (PVDF) film was achieved by cyclic voltammetry to yield well-ordered poly(3-methylthiophene) (P3MT) thin films with anisotropic structural and conductivity properties. The conductivity of P3MT along the direction perpendicular to the chain direction of PVDF, after electrochemical dedoping, is 59 ± 3 S cm−1, while that along the PVDF chain direction is 1.2 ± 0.4 S cm−1. The high conductivity of the P3MT is attributed to the well-ordered structure with its flat-on single crystals as confirmed by electron diffraction and Reflection Absorption Infra-red Spectroscopy (RAIRS). The data are consistent with P3MT chains aligned with π–π stacking perpendicular to the chain direction of the PVDF substrate. Epitaxial electropolymerization is an unusual method of preparing highly ordered thin films of organic semiconductors.
Co-reporter:Bing He, Zhongjie Ren, Shouke Yan and Zhaohui Wang
Journal of Materials Chemistry A 2014 vol. 2(Issue 30) pp:6048-6055
Publication Date(Web):15 May 2014
DOI:10.1039/C4TC00481G
In this study, well-ordered multilayer graphene has been obtained via highly oriented polyethylene (OPE) films. Optical microscopy (OM), atomic force microscopy (AFM), Raman laser spectroscopy, scanning electron microscopy (SEM) and transmission electron microscopy (TEM) results indicated that the obtained graphene films were continuous and uniform in lattice orientation. Optical and electrical characterization of the prepared graphene revealed that the thin films are stable in air and exhibit better optical and electrical properties than that obtained from non-oriented polyethylene (nOPE).
Co-reporter:Dianming Sun, Xiaokang Zhou, Huihui Li, Xiaoli Sun, Yonghao Zheng, Zhongjie Ren, Dongge Ma, Martin R. Bryce and Shouke Yan
Journal of Materials Chemistry A 2014 vol. 2(Issue 39) pp:8277-8284
Publication Date(Web):03 Sep 2014
DOI:10.1039/C4TC01467G
A universal hybrid polymeric host (PCzSiPh) for blue and deep blue phosphors has been designed and synthesized by incorporating electron-donating carbazole as pendants on a polytetraphenylsilane main chain. The polymer PCzSiPh (4) has a wide bandgap and high triplet energy (ET) because of the tetrahedral geometry of the silicon atom in the tetraphenylsilane backbone. The distinct physical properties of good solubility, combined with high thermal and morphological stability give amorphous and homogenous PCzSiPh films by solution processing. As a result, using PCzSiPh as host with the guest iridium complex TMP-FIrpic gives blue phosphorescent organic light-emitting diodes (PhOLEDs) with overall performance which far exceeds that of a control device with poly(vinylcarbazole) (PVK) host. Notably, FIrpic-based devices exhibit a maximum external quantum efficiency (EQE) of 14.3% (29.3 cd A−1, 10.4 lm W−1) which are comparable to state-of-the-art literature data using polymer hosts for a blue dopant emitter. Moreover, the versatility of PCzSiPh extends to deep blue PhOLEDs using FIr6 and FCNIrpic as dopants, with high efficiencies of 11.3 cd A−1 and 8.6 cd A−1, respectively.
Co-reporter:Quan Li, Jiandong Zhou, Liguo Chai, Jamil Memon, Zhongjie Ren, Huihui Li, Xiaoli Sun and Shouke Yan
Polymer Chemistry 2014 vol. 5(Issue 14) pp:4293-4303
Publication Date(Web):01 Apr 2014
DOI:10.1039/C4PY00119B
The crystallization and melting behaviors of PBA thin films with different thicknesses placed on Si wafers and PVPh surfaces under varied conditions were studied by using grazing incident X-ray diffraction (GIXD) and infrared reflection-absorption spectroscopy (IR-RAS). The results show that crystallization of PBA during the solvent evaporation process on either Si wafer or PVPh surfaces produces always β-form crystals regardless of the film thickness. However, the melting behavior of the β-PBA crystals on the PVPh surface is quite different from those on a Si wafer. On the Si wafer, the melting of β-PBA crystals in films with thicknesses ranging from 39 to 293 nm is not altered obviously. The β-to-α phase transition always takes place during the heating process before melting. By contrast, on the PVPh sublayer, the melting of the β-PBA crystals depends on the thicknesses of both PBA and PVPh layers. A thinner PBA layer and a thicker PVPh layer favor a direct melting of the β-PBA crystals without the occurrence of β-to-α phase transition. The phase transition temperature of the PBA film with the same thickness reduces with the thickening of the PVPh layer. IR-RAS results indicate that the intermolecular hydrogen bonds increase with temperature and thickening of PVPh sublayers. The reduced phase transition temperature can be attributed to the increasing hydrogen bonds formed at the interface of PVPh and PBA. The surface property of PVPh films is investigated conveniently through monitoring the formation of hydrogen bonds between PVPh and PBA at the interface. The formation of hydrogen bonds at temperatures which are much lower than the glass transition temperature of PVPh suggests that the segmental mobility of PVPh molecular chains evolves in the glassy state. It is the higher segmental mobility of PVPh in the thicker film that alters the phase transition behavior of the PBA layer.
Co-reporter:Dianming Sun, Zhaomin Yang, Xiaoli Sun, Huihui Li, Zhongjie Ren, Junteng Liu, Dongge Ma and Shouke Yan
Polymer Chemistry 2014 vol. 5(Issue 17) pp:5046-5052
Publication Date(Web):02 May 2014
DOI:10.1039/C4PY00450G
In this work, a triphenylamine based polysiloxane (PTPAMSi) has been successfully synthesized. The PTPAMSi exhibits a high decomposition temperature (Td = 377 °C) and glass transition temperature (Tg = 63 °C). It also displays good film-forming ability, high morphological stability and good miscibility with the dopant FIrpic as revealed by atomic force microscopy (AFM). The silicon–oxygen linkage of PTPAMSi disrupts its conjugation and results in a sufficiently high triplet energy level (ET = 2.9 eV). A FIrpic-based device using PTPAMSi as a host shows a turn-on voltage of 6.8 V, a maximum external quantum efficiency of 3.8%, and a maximum current efficiency of 7.6 cd A−1. These results demonstrate that using polysiloxane to modify triphenylamine is a promising approach to improve the physical properties of triphenylamine while maintaining its photophysical and electrochemical properties.
Co-reporter:Dianming Sun, Qiang Fu, Zhongjie Ren, Huihui Li, Dongge Ma and Shouke Yan
Polymer Chemistry 2014 vol. 5(Issue 1) pp:220-226
Publication Date(Web):08 Aug 2013
DOI:10.1039/C3PY00840A
Alternating copolymers with both hole and electron transporting side groups as bipolar hosts are of great interest for deep blue phosphorescent devices due to the uniform distribution of electrons and holes within the emitting layer. In this work, we synthesized an efficient alternating copolysiloxane-based host material poly(phenylcarbazole-alt-triphenylphosphine oxide) siloxane (PCzPOMSi) with phenylcarbazole and triphenylphosphine oxide moieties linked to the backbone of polysiloxane. PCzPOMSi exhibits a high decomposition temperature (Td = 437 °C) and glass transition temperature (Tg = 118 °C), and it can form a stable amorphous state. The silicon–oxygen linkage of PCzPOMSi disrupts its conjugation and results in a sufficiently high triplet energy level (ET = 3.0 eV). A bis((3,5-difluoro-4-cyanophenyl)pyridine) iridium picolinate (FCNIrpic)-based device using PCzPOMSi as a host shows a turn-on voltage of 7.7 V, a maximum external quantum efficiency of 4%, and a maximum current efficiency of 8.5 cd A−1. These results demonstrate that a well-designed alternating copolysiloxane-based host is a promising approach to realize high performance solution-processed deep blue PhPLEDs.
Co-reporter:Xiaoli Sun, Junteng Liu, Isao Takahashi and Shouke Yan
RSC Advances 2014 vol. 4(Issue 74) pp:39101-39109
Publication Date(Web):19 Aug 2014
DOI:10.1039/C4RA04752D
Synchrotron small-angle X-ray scattering (SAXS) and wide-angle X-ray diffraction (WAXD) are used to monitor the melting and βα transition behavior of β-PBA and the β-PBA/PVPh blend during the heating process. After melt recrystallized at 10 °C, the β crystals are obtained. The lamellar thickness of β crystals in the neat PBA is similar to that in its PBA/PVPh blend and the long period for the former one is shorter than the latter one. At lower heating rate, α crystals start to appear at 39 °C suggesting the βα phase transition occurs. Compared with the neat PBA, the β-PBA in the blend transits to α crystals at a higher rate. At a higher heating rate, β crystals melt directly. Both at the lower and higher heating rate, the crystal structure along the a-axis is much more stable than that along b-axis in the β crystals. Moreover, the heating rate does not play a role in the melting mechanism of the β crystals. The melting of the β crystals in the neat PBA and its PBA/PVPh blend chose different mechanisms. The melting mechanism of the β crystals in the PBA/PVPh blend is attributed to the sequential melting. On the contrary, the melting of the β phase in the neat PBA is complex. Besides the peak of q = 0.54 nm−1, a new peak appears at q = 0.32 nm−1 in the SAXS profiles in the heating process suggesting the appearance of a population with a larger long period. The presence of two peaks is caused by the coexistence of two kinds of lamellar stacks. And the partial melting of thinner β-PBA lamellae occurs firstly in one kind of lamellar stacks.
Co-reporter:Bing He, Yuxia Shen, Zhongjie Ren, Chengyi Xiao, Wei Jiang, Lili Liu, Shouke Yan, Zhaohui Wang, Zhongzhen Yu
Organic Electronics 2014 Volume 15(Issue 3) pp:685-691
Publication Date(Web):March 2014
DOI:10.1016/j.orgel.2013.12.029
•We reported a method of preparing large size of single and few-layer graphene sheets.•We controlled the defect of the graphene by changing thermal treatment temperature.•We enhanced the field-effect performance of graphene by increasing temperature.•The graphene device exhibited relatively high p-type transistor characteristics.Defect-controllable reduction approach of graphene is demonstrated. By in situ thermal reduction from graphene oxide on silicon wafer (300 nm SiO2), large size (∼15 μm) of single and few-layer graphene with highly improved electrical properties has been prepared. The effects of increasing annealing temperature on reducing the defect, restoring the lattice and enhancing the field-effect performance of graphene are proved. The characteristics of the sample were analyzed using optical microscope (OM), atomic force microscope (AFM), X-ray photoelectron spectra (XPS), Raman laser, semiconductor parameter analyzer and a micromanipulator. The devices based on the obtained few-layer graphene exhibit relatively high p-type transistor characteristics (6.2 cm2/V s) in the atmospheric environment.Graphical abstractWe present here the synthesis, characterization, and enhanced performances of thin film transistors based on graphene from thermal treatment.
Co-reporter:Qi Liu;Hui-hui Li;Shou-ke Yan 闫寿科
Chinese Journal of Polymer Science 2014 Volume 32( Issue 4) pp:509-518
Publication Date(Web):2014 April
DOI:10.1007/s10118-014-1417-x
Matrix/fiber composites of β-form isotactic polypropylene (iPP) matrix and α-iPP or PA6 fibers were prepared by laminating technique under different preparation temperatures. The mechanical properties and interfacial morphologies of these composites were studied by tensile test, optical microscopy and scanning electron microscopy, respectively. The experimental results show that the tensile yield load and tensile modulus of β-iPP/PA6 matrix/fiber systems increased significantly at the expense of elongation at break. These mechanical properties show essentially no dependence on the sample preparation temperature. On the other hand, the mechanical properties of iPP matrix/fiber single polymer composites depend strongly on the sample preparation temperature. At low sample preparation temperature, e.g., 172 °C, the solid α-iPP fiber induces α-iPP crystallization, leading to the formation of α-iPP transcrystalline layer around the fiber. This results in a remarkable increment of the tensile yield load and tensile modulus. The elongation at break is also much better than that of the iPP/PA6 matrix/fiber system. It reflects a better interfacial adhesion of the single polymer composite compared with the iPP/PA6 composite. At higher sample preparation temperature, e.g., 174 °C or 176 °C, the partial surface melting of the oriented fiber allows interdiffusion of iPP molecular chains in the molten fiber and matrix melt. The penetration of matrix chains into the molten iPP fiber results in some iPP molecular chains being included partially in the recrystallized fiber and the induced β-transcrystalline layers. This kind of configuration leads to an improvement of interfacial adhesion between the fiber and matrix, which causes a simultaneous increase of the tensile yield load, tensile modulus and elongation at break of β-iPP.
Co-reporter:Jiandong Zhou, Hongyi Gan, Zhongjie Ren, Huihui Li, Jianming Zhang, Xiaoli Sun, Shouke Yan
Polymer 2014 Volume 55(Issue 22) pp:5821-5828
Publication Date(Web):23 October 2014
DOI:10.1016/j.polymer.2014.09.018
The cold crystallization and melting behavior of poly(3-hydroxybutyrate)(PHB) layer on amorphous Poly(vinyl phenol) (PVPh) and Si wafer substrate were studied by using Grazing incidence X-ray diffraction and infrared reflection-absorption spectroscopy. Compared to the PHB on Si wafer, the PVPh layer shows great influence on the crystallization and melting behavior of PHB layer. The depression extent of melting temperature increases with the increase of PVPh thickness when the thickness of PVPh is smaller than a critical value. Infrared reflection-absorption spectroscopy study is carried out to better understand the structure evolution of PHB and its interaction with PVPh in the heating process. By monitoring and decomposing the CO stretching bands, several points can be identified: (1) melting temperature decreases with PVPh thickening; (2) the fraction of intermolecular hydrogen bonds formed between the OH groups of PVPh and CO groups of PHB is very small below glass transition temperature of PVPh and it increases significantly above 100 °C. Moreover the fraction increases with PVPh thickness. The effect of PVPh thickness on the formation of hydrogen bonds is attributed to the roughness, molecular mobility and/or molecular orientation of PVPh.
Co-reporter:Dr. Dianming Sun;Dr. Zhaomin Yang;Dr. Zhongjie Ren;Dr. Huihui Li; Martin R. Bryce; Dongge Ma; Shouke Yan
Chemistry - A European Journal 2014 Volume 20( Issue 49) pp:16233-16241
Publication Date(Web):
DOI:10.1002/chem.201402374
Abstract
A new oligosiloxane derivative (ODCzMSi) functionalized with the well-known 1,3-bis(9-carbazolyl)benzene (mCP) pendant moiety, directly linked to the silicon atom of the oligosiloxane backbone, has been synthesized and characterized. Compared to mCP, the attachment of the oligosiloxane chain significantly improves the thermal and morphological stabilities with a high decomposition temperature (Td=540 °C) and glass transition temperature (Tg=142 °C). The silicon–oxygen linkage of ODCzMSi disrupts the backbone conjugation and maintains a high triplet energy level (ET=3.0 eV). A phosphorescent organic light-emitting diode (PhOLED) using iridium bis(4,6-difluorophenyl)pyridinato-N,C2 picolinate (FIrpic) as the emitter and ODCzMSi as the host shows a relatively low turn-on voltage of 5.0 V for solution-processed PhOLEDs, maximum external quantum efficiency of 9.2 %, and maximum current efficiency of 17.7 cd A−1. The overall performance of this device is competitive with the best reported solution-processed blue PhOLEDs. Memory devices using ODCzMSi as an active layer exhibit non-volatile write-once read-many-times (WORM) characteristics with high stability in retention time up to 104 s and a low switch on voltage. This switching behaviour is explained by different stable conformations of ODCzMSi with high or low conductivity states which are obtained under the action of electric field through a π–π stacking alignment of the pendant aromatic groups. These results with both PhOLEDs and memory devices demonstrate that this oligosiloxane–mCP hybrid structure is promising and versatile for high performance solution-processed optoelectronic applications.
Co-reporter:Xiaoli Sun, Zhongjie Ren, Junteng Liu, Isao Takahashi, and Shouke Yan
Langmuir 2014 Volume 30(Issue 25) pp:7585-7592
Publication Date(Web):2017-2-22
DOI:10.1021/la501542h
The structure evolution of P3HT thin films on Si wafer and PVPh covered Si wafer during heating, thermal annealing, and melt recrystallization processes has been studied in detail using X-ray analysis techniques. The effect of substrate on the crystallization behavior and interface structure of P3HT films was explored. For the P3HT films deposited on the Si substrate, it was found that the stability of P3HT crystals is orientation dependent. The crystals oriented with b-axis normal to the substrate, that is, a face-on molecular orientation, are less stable than those with the a-axis arranged normal to the substrate (side-on molecular orientation). Thermal annealing temperature plays an important role in the molecular structure of P3HT including crystal structure, film thickness, and surface roughness. After annealing at relatively high temperature, new crystals form during the cooling process accompanied by the shrinking of a-axis. Moreover, the melt recrystallization favors the formation of more stable P3HT crystals with side-on molecular orientation. The PVPh substrate does not affect the crystallization behavior of solution cast P3HT significantly but inhibits the formation of P3HT crystal with face-on molecular orientation. However, the interfacial morphology of P3HT and PVPh changes by annealing at elevated temperature. The P3HT/PVPh interface changes from a sharply defined one into a diffused one at around 160 °C. The PVPh sublayer inhibits the melt recrystallization of P3HT to some extent, leading to a slight expansion of the a-axis.
Co-reporter:Li Li;Jun-teng Liu;Zhong-jie Ren;Shou-ke Yan 闫寿科
Chinese Journal of Polymer Science 2014 Volume 32( Issue 9) pp:1199-1209
Publication Date(Web):2014 September
DOI:10.1007/s10118-014-1497-7
The crystallization behavior of PEOs with molecular weight of 10k and 200k as well as their blends was studied in details. The results show that the lower molecular weight PEO crystallizes with faster crystallization rate as judged from a shorter time for completing the crystallization. On the other hand, the higher molecular weight PEO crystallizes at relatively higher temperature, indicating an early start of crystallization compared with the lower molecular weight one. The blends of these two PEOs with different blend ratios always cocrystallize during the cooling processes. It is confirmed that mixing of the 10k PEO with the 200k one is in favor of the crystallization of the system. This is not only demonstrated by the early start of the crystallization at higher crystallization temperature, and also a faster crystal growth of the blend with respect to the 200k PEO. The crystallization of the blends at higher temperature is caused by an early start of nucleation and an increment of nucleus density. This may originate from the density fluctuation of the blend and a reduction in energy barrier for nucleation. Moreover, it is found that the crystallinity of the 10k PEO rich blends increases with increasing concentration of the 10k PEO. This is caused by the solvent effect of the 10k PEO toward the 200k PEO. On the other hand, the crystallinity of the 30/70 (10k/200k) PEO blend is decreased a little bit. This may be a balanced result of the improved crystallization of the 200k PEO at the expense of the high crystallization ability of the 10k PEO.
Co-reporter:Dianming Sun, Qiang Fu, Zhongjie Ren, Wei Li, Huihui Li, Dongge Ma and Shouke Yan
Journal of Materials Chemistry A 2013 vol. 1(Issue 34) pp:5344-5350
Publication Date(Web):03 Jul 2013
DOI:10.1039/C3TC31108B
The efficient host materials containing carbazole moieties linked to the backbone of polysiloxane through a phenyl bridge have been synthesized and characterized. They exhibit good film forming ability, high thermal decomposition temperatures and suitable glass transition temperatures, so as to form stable amorphous states. Moreover, the silicon–oxygen linkage disrupts their conjugation and results in a sufficiently high triplet energy level (3.0 eV). Iridium bis(4,6-difluorophenyl)pyridinato-N,C2 picolinate (FIrpic)-based devices using them as hosts show good overall performance with low efficiency roll-off. The device using PCzMSi as the host demonstrates the best performance with a maximum current efficiency of 22.8 cd A−1, a maximum power efficiency of 9.4 lm W−1 and a maximum external quantum efficiency of 11.9% at a practical luminance of 1165 cd m−2. Even at a brightness of 5000 cd m−2 level, the external quantum efficiency (EQE) still remains as high as 10%, suggesting a gentle roll-off of device efficiency at high current density. In addition, typically, the host PCzMSi film displays good mechanical performance by a nanoindentation technique to meet the practical application. These results demonstrate that the design of polysiloxane-based host materials is a promising approach to realize high performance solution-processed blue phosphorescent polymer light emitting diodes (PhPLEDs).
Co-reporter:Tingjie Zhang, Dianming Sun, Xiangkui Ren, Lili Liu, Guanyin Wen, Zhongjie Ren, Huihui Li and Shouke Yan
Soft Matter 2013 vol. 9(Issue 45) pp:10739-10745
Publication Date(Web):06 Sep 2013
DOI:10.1039/C3SM52054D
A series of symmetric and asymmetric 1,6,7,12-tetrachloroperylene bisimides (PBICls) were synthesized and modified by siloxane substituents at the imide nitrogen atom. Siloxane substitutions do not apparently affect the electronic properties of PBICIs as demonstrated by CV experiments. They display both thermotropic and lyotropic liquid crystalline behaviors. The effect of different siloxane substituents on their liquid crystal structures was investigated in detail. Small angle X-ray scattering indicates that PBICls adopt hexagonal columnar packing in thermotropic liquid crystals. In addition, PBICls exhibit good optical properties, good solubility and film-forming ability. Thus the oriented films of PBICl liquid crystals could be easily fabricated by mechanical shear, which show anisotropic properties in UV-vis absorption spectra.
Co-reporter:Yannan Quan, Huihui Li, and Shouke Yan
Industrial & Engineering Chemistry Research 2013 Volume 52(Issue 13) pp:4772
Publication Date(Web):March 8, 2013
DOI:10.1021/ie303200z
The crystallization of isotactic polypropylene (iPP) in the presence of its own fiber or/and α nucleating agents, i.e., DBS and NA11, was studied. The results show that both nucleating agents exhibit nucleation ability toward iPP and accelerate iPP melt crystallization. This is manifested by an upward shift of crystallization temperature by up to 10 °C compared with its bulk crystallization. The iPP fiber exhibits also high nucleation ability toward the iPP matrix as demonstrated by the formation of transcrystalline layers. The crystallization of iPP in the nucleated iPP matrix/fiber system shows that the nucleating agents do not affect the transcrystallization of iPP surrounding its fiber. This indicates that the fiber exhibits higher nucleation ability toward iPP than the nucleating agents. On the basis of the exact same chemical and crystallographic structures of the iPP fiber and matrix, the results demonstrate the importance of structure similarity and matching between the crystallographic structures in the heterogeneous nucleation of polymers.
Co-reporter:Haixin Zhou
Macromolecular Chemistry and Physics 2013 Volume 214( Issue 6) pp:639-653
Publication Date(Web):
DOI:10.1002/macp.201200530
Abstract
Polymer epitaxy defines the crystallographic orientation of overgrowing polymer. It controls several aspects of the structure of semicrystalline polymers, such as fixed mutual chain orientation, certain crystal structures of polymorphic polymers, and the spatial arrangement of planar backbone molecular chains. Therefore, epitaxial crystallization provides a simple and efficient way to fabricate special structures with improved properties and even introduce new functionality for polymeric materials. Besides achieving structural control of single polymer systems, technical development in the field of structural and morphological manipulation of multiphase and multicomponent polymer systems is another important and challenging issue for the advanced application of polymeric materials.
Co-reporter:Xiaoli Sun;Huihui Li;Ingo Lieberwirth
Journal of Applied Polymer Science 2013 Volume 129( Issue 4) pp:1784-1792
Publication Date(Web):
DOI:10.1002/app.38876
Abstract
A micro-structured polymer film was prepared by drying a droplet of a ternary polymer solution of polystyrene (PS), poly(vinyl pyrrolidone) (PVP), and chloroform. Within a certain weight ratio of PS to PVP an ordered pattern of cylindrical PVP domains was formed on the film surface. The diameter of the individual PVP domains was in the order of 2–3 μm. The effect of polymer weight ratios on the surface morphology was investigated by atomic force microscopy. Additionally, scanning electron microscopy of cross-sections of the polymer composite film yielded supplementary information on the bulk morphology and revealed an unexpected complex structure underneath the surface pattern. The reasons for this formation mechanism possibly included aspects of phase separation, convective transport in a drying droplet, and the continuous increase of viscosity during solvent evaporation. At a certain solvent concentration in the evaporation path, it will lead to a vitrification of any structure. The “evolution time”, the time between the onset of phase separation and this “point of vitrification”, will determine the resulting film morphology. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013
Co-reporter:Xiaoli Sun, Zhen Chen, Feng Wang, Shouke Yan, and Isao Takahashi
Macromolecules 2013 Volume 46(Issue 4) pp:1573-1581
Publication Date(Web):February 8, 2013
DOI:10.1021/ma302349a
The crystallization behavior of poly(3-hydroxybutyrate) (PHB) thin films on poly(vinylphenol) (PVPh) substrate was investigated by surface-sensitive grazing incident X-ray scattering and infrared reflection–absorption spectroscopy techniques. Compared with the crystallization of PHB on a Si wafer, the PVPh sublayer did not significantly affect the crystallization behavior of PHB in solution-cast samples, while significantly inhibited the melt crystallization of PHB. For films thinner than 175 nm, amorphous PHB was always fabricated irrespective of melt crystallization temperature. Only when the film thickness increased to 185 nm, the PHB started to crystallize at temperatures above 53 °C. The PHB crystals preferred to orient with the b-axes perpendicular to substrate. The inhibition of PHB melt crystallization was attributed to the thickness confinement and interdiffusion of PVPh and PHB, which caused a concentration gradient of PVPh in the PHB layer. From the thickness dependence of crystallization behavior, the PHB film can be divided into two layers: the inactive layer with high fraction of inter C═O and stable amorphous state; the interactive layer in which crystallization of PHB is sensitive to temperature. The existence of inactive layer accounts for the formation of crystals oriented with b-axes perpendicular to substrate.
Co-reporter:Qi Liu, Xiaoli Sun, Huihui Li, Shouke Yan
Polymer 2013 Volume 54(Issue 17) pp:4404-4421
Publication Date(Web):2 August 2013
DOI:10.1016/j.polymer.2013.04.066
In polymer processing operations, the molten polymer chains are frequently subjected to shear or/and elongation flow fields, which will produce molecular chain orientation of the melt. This leads to the orientation-induced crystallization has been an important subject in the field of polymer physics. Systematic studies indicated that the chain orientation influences the crystallization kinetics, the final morphology as well as the polymorphic behavior of the polymers. In this article, the effects of preorientation on the crystallization of isotactic polypropylene (iPP) concerning the above mentioned aspects have been reviewed. In particular, the formation mechanism of orientation-induced β-iPP crystallization has been discussed according to the recent experimental results. It is suggested that the local order of the macromolecular chain segments in the melt is most important for β-nucleation of iPP. The formation of β-iPP nuclei may be restricted in a certain chain orientation window of the iPP melts. Chain orientation outside of this window results in the formation of α-iPP.Figure optionsDownload full-size imageDownload as PowerPoint slide
Co-reporter:Chun-zhu Yan;Lin Guo;Xiao-li Sun 孙晓丽
Chinese Journal of Polymer Science 2013 Volume 31( Issue 3) pp:407-418
Publication Date(Web):2013 March
DOI:10.1007/s10118-013-1240-9
The specular and off-specular X-ray reflectivities were efficiently employed to study the evolution of surface morphology as a function of temperature in a single layer of poly(3-hydroxybutyrate) (PHB) and a bilayer of PHB/poly(vinyl phenol) (PVPh) on Si substrates. The results indicate that the changes of thickness and surface roughness caused by pre-melting of PHB crystals are not obvious for the single layer, whereas the surface roughness of the PHB layer and the intensity of the off-specular X-ray reflectivity for the bilayer exhibit a remarkable non-monotonic change in the temperature range of 100–150°C; the roughness parameter evaluated by the specular X-ray reflectivity reaches its maximum at 120°C. The interaction at the interface between PVPh and PHB certainly contributes to the non-monotonic changes. Such interaction also affects the crystallization and melting behavior of PHB thin film greatly. The crystallization of PHB thin film is inhibited even on the glassy surface of PVPh sublayer. In the melting process, the PHB crystals on PVPh sublayer feature a three-section melting curve separated by a plateau region of 120–140°C.
Co-reporter:Zhen Chen
Science Bulletin 2013 Volume 58( Issue 3) pp:328-335
Publication Date(Web):2013 January
DOI:10.1007/s11434-012-5589-x
Time-resolved FTIR, WAXD/SAXS and DSC have been used to investigate the structural variation of non-isothermally crystallized poly(trimethylene terephthalate) (PTT) during the heating process. The three-phase model: the lamellar phase, the mobile amorphous phase (MAP) and the rigid amorphous phase (RAP) between lamellae is suggested to describe the structure of melt-crystallized PTT. According to FTIR results, the conformation of RAP in the constrained state is different from that of MAP. The increased content of amorphous phase in the temperature range from 120 to 192°C is ascribed to the relaxation of RAP, rather than the melting of defective crystals. When the PTT is heated to a temperature above 192°C, the recrystallization/crystal perfection of original defective lamellae occurs without a pre-melting process, which leads to an increase in lamellar thickness and probably connects two adjacent lamellar stacks. This is responsible for an increase in crystallinity as well as a higher major melting temperature.
Co-reporter:Zhen Chen;Jun Luo
Colloid and Polymer Science 2013 Volume 291( Issue 4) pp:757-766
Publication Date(Web):2013 April
DOI:10.1007/s00396-012-2786-8
The structure and thermal behavior of cold-crystallized poly(trimethylene terephthalate) (PTT) are revealed in detail by DSC, AFM, TEM, and WAXD as well as in situ FTIR and SAXS techniques. There is no effect of crystallization temperature and initial state on the crystal modification, yet the morphology is strongly affected by these two factors. First, the small rod-like lamellae for PTT are obtained during the cold crystallization instead of the spherulites formed in the melt crystallization. Second, the edge-on lamellar orientation in thin films is identified during the cold crystallization. The thickness and the lateral width of rod-like lamellae get larger and larger with increasing crystallization temperature. Thin lamellar crystals assemble randomly when the cold-crystallization temperature is lower, while lamellar stacks composed of thicker lamellae are observed when the PTT was annealed at elevated temperature. Moreover, for the cold-crystallized PTT, the final melting temperature does not vary with the crystallization temperature. This phenomenon is explained by the structural improvement during the heating process. For the cold-crystallized PTT sample at lower temperature, three transitions occur when it is heated again: the relaxation of the rigid amorphous phase, the reorganization of molecules in the intermediate phase, and then the melt–recrystallization behavior. Those transitions finally lead to thicker lamellae besides a higher crystallinity before the final fusion. Therefore, the final melting peak of these lamellae is at the same temperature.
Co-reporter:Jiang Wu;Hai-xin Zhou;Qi Liu;Shou-ke Yan 闫寿科
Chinese Journal of Polymer Science 2013 Volume 31( Issue 6) pp:841-852
Publication Date(Web):2013 June
DOI:10.1007/s10118-013-1269-9
The dependence of properties on the structure and morphology of semicrystalline polymers offers an effective way to tailor the properties of these materials through structure control. To this end, establishing the structure and property relationship is of great importance. For a right characterization of the crystal structure, several techniques can be used. Among these techniques, electron diffraction has its advantage for determining the crystal structure related to specific formation condition since it can combine with bright and dark fields observation of the sample. This feature article describes the application of electron diffraction in determining the crystal structure of semicrystalline polymers with elaborately selected examples. We focus on how the electron diffraction can be used to disclose the crystal structure, mutual orientation of different crystals, as well as the disorders included in the polymer crystals.
Co-reporter:Chun-zhu Yan;Lin Guo;Hai-bo Chang 常海波
Chinese Journal of Polymer Science 2013 Volume 31( Issue 8) pp:1173-1182
Publication Date(Web):2013 August
DOI:10.1007/s10118-013-1292-x
The crystallization behavior of poly(ethylene adipate) (PEA) on highly oriented high-density polyethylene (PE) substrate both from solution and isotropic melt was studied by means of optical microscopy, differential scanning calorimetry, atomic force microscopy and electron diffraction. The results show that the PE influences the crystallization of PEA strongly, which results in an epitaxial growth of PEA with well ordered structure. At the boundary of the PE substrate, a transcrystalline PEA layer is observed. Fine structural observation illustrates that the PEA grows on the PE substrate in edgeon lamellae with fixed orientation. Electron diffraction demonstrates that the epitaxial organization of PEA on PE occurs with both polymer chains parallel, which leads to the (00l) PEA diffractions inclined ±23.5° to the chain direction of PE crystals. Combining the real space morphological observation and electron diffraction results, it is concluded that the epitaxial PEA edge-on lamellae are folded in the {00l} lattice planes.
Co-reporter:Ce Tu, Shidong Jiang, Huihui Li, and Shouke Yan
Macromolecules 2013 Volume 46(Issue 13) pp:5215-5222
Publication Date(Web):June 21, 2013
DOI:10.1021/ma400743k
Cold crystallization of poly(l-lactic acid) (PLLA) from amorphous state on highly oriented polyethylene (PE) substrate has been studied by electron diffraction and infrared spectroscopy. Both electron diffraction and infrared spectroscopy analyses show that the PLLA in the as-prepared PLLA/PE double layers is in the amorphous state. Annealing of the as-prepared PLLA/PE samples at 130 °C leads to the cold crystallization of PLLA. It is confirmed that the PLLA grown on the oriented PE surface exhibits high orientation with molecular chains aligned perpendicular the chain direction of PE, indicating the occurrence of heteroepitaxy of PLLA on the PE substrate. This provides a first example of perpendicular chain orientation of polymer epitaxy. Moreover, it demonstrates the capability of polymer epitaxy from amorphous state through annealing. Infrared spectroscopy analysis on the as-prepared PLLA/PE double layers shows that the orientation of PLLA molecules in contact with the PE substrate exists already in the amorphous state. It is these oriented PLLA chains in amorphous phase that transform into crystal nuclei during cold crystallization and initiate the oriented overgrowth of PLLA on the PE substrate.
Co-reporter:Zhongjie Ren, Dianming Sun, Jianming Zhang and Shouke Yan
Journal of Materials Chemistry A 2012 vol. 22(Issue 36) pp:18839-18846
Publication Date(Web):02 Aug 2012
DOI:10.1039/C2JM34379G
Reduced graphene oxide (rGO) sheets covalently functionalized with n-type tetrachloroperylene diimide (PDI) and oligomeric PDI have been prepared by a two-step approach. Firstly, graphene oxide (GO) was modified by an amidation reaction with 3-aminopropyldimethylethoxylsilane or 3-aminopropyldiethoxylmethylsilane, during which GO was reduced thermally. They then react with the silanol modified PDI by dehydration condensation to obtain PDI and oligomeric PDI modified rGO (rGO–PDI and rGO–(PDI)n). The successful preparation of rGO–PDI and rGO–(PDI)n were confirmed by FTIR, Raman, X-ray photoelectron spectroscopy and XRD. The morphologies of rGO–PDI and rGO–(PDI)n sheets were studied using AFM. It was found that surface morphologies and height of rGO–PDI and rGO–(PDI)n sheets are dependent on the solvents used for casting due to differences in the solubility of PDI. Moreover, the fluorescence emission spectrum of rGO–PDI and rGO–(PDI)n shows strong fluorescence quenching and blue shift, especially in ethanol. Current sensing atomic force microscopy (CSAFM) indicated that the rGO–PDI composite shows quite different electric conductivity and optical properties with grafting efficiency and different solvents used for casting. Significantly, the electronic conductivity of rGO–(PDI)n increased by 2–3 orders of magnitude compared to rGO–PDI.
Co-reporter:Zhongjie Ren, Huihui Li, Xiaoli Sun, Shouke Yan, and Yuming Yang
Industrial & Engineering Chemistry Research 2012 Volume 51(Issue 21) pp:7273-7278
Publication Date(Web):May 8, 2012
DOI:10.1021/ie3006098
A new method to produce high toughness Poly(lactic acid) (PLA) was introduced in this study. The blends of low molecular weight triacetin (TAC) and oligomeric poly(1,3-butylene glycol adipate) (PBGA) were first used as multiple plasticizers to lubricate PLA and then the plasticized PLA cross-linked with triallyl isocyanurate (TAIC) through electron beam irradiation. In this way, a kind of stable PLA material with high elongation at break was obtained. The elongation at break of the prepared material is more than 260% with a tensile strength of 23.5 MPa when the irradiation dose is 10 Mrad. Detailed studies of Fourier transform infrared (FTIR) spectra and viscosity experiments revealed that both the self-cross-linking of the PLA molecular chains and the cross-linking between the molecular chains of PLA and PBGA could occur. This results in the remarkable improvement in the performance of the obtained materials.
Co-reporter:Qi Liu;Huihui Li;Zhaobin Qiu
Polymer International 2012 Volume 61( Issue 9) pp:1417-1424
Publication Date(Web):
DOI:10.1002/pi.4226
Abstract
β-isotactic polypropylene (β-iPP) cylindritic crystals were produced in homogeneous iPP fiber–matrix composites and heterogeneous polyamide (PA)–iPP fiber–matrix composites under different sample preparation conditions. The melt recrystallization behaviors of the β-iPP crystals obtained in the homogeneous and heterogeneous composites were studied by optical microscopy. The experimental results show that, by heating the sample to 180 °C, the birefringence contributed by the iPP crystals in both α- and β-forms disappears completely. During the cooling process, the β-iPP crystals in the homogeneous composite appear again, while the iPP in the heterogeneous composite crystallizes in its α-form. This demonstrates the different origins of the β-iPP cylindrites in the homogeneous and heterogeneous composites. While the β-iPP cylindrites in the heterogeneous composite are associated with the sample preparation procedure, the β-iPP cylindrites in the homogeneous composite are produced by recrystallization of the molten but incompletely relaxed iPP fibers. In situ observation of the melt recrystallization process shows that the molten iPP oriented fibers crystallize first during the cooling process at relatively higher temperature in the α-form. Abundant randomly dispersed β-iPP nuclei formed at the surface of the recrystallized iPP fibers, which generate the β-iPP cylindrites. Copyright © 2012 Society of Chemical Industry
Co-reporter:Guang-peng Wu;Shi-dong Jiang;Xiao-bing Lu 吕小兵
Chinese Journal of Polymer Science 2012 Volume 30( Issue 4) pp:487-492
Publication Date(Web):2012 July
DOI:10.1007/s10118-012-1171-x
An example of crystalline CO2-based polymer from the asymmetric alternating copolymerization of CO2 and cyclohexene oxide is reported. Isotacticity of poly(cyclohexene carbonate) (PCHC) has the critical influence on the crystallinity, and only copolymers with a isotacticity of more than 90% are crystallizable. The stereoregular PCHC is a typical semi-crystalline thermoplastic, and possesses a high melting point (Tm) of 215–230°C and a decomposition temperature of ca. 310°C. The spherulitic morphology of (R)-PCHC grows in a clockwise spiral from a center, and that of (S)-PCHC is a counterclockwise spiral, while the stereocomplex of (S)-PCHC/(R)-PCHC (1/1 mass ratio) presents lath-like dendritic crystal. The novel crystalline CO2-based polycarbonate represents a rare example of optically active polymers with unique crystallization behavior. Our findings reflect the critical influence of stereoregularity on the crystallization for this kind of polymeric materials, and may lead to developments of thermal-resistance CO2 copolymers for application in engineering thermoplastics.
Co-reporter:Xiaoli Sun, Akihisa Tokuda, Yusuke Oji, Takashi Nakatani, Hideto Tsuji, Yukihiro Ozaki, Shouke Yan, and Isao Takahashi
Macromolecules 2012 Volume 45(Issue 5) pp:2485-2493
Publication Date(Web):February 22, 2012
DOI:10.1021/ma202543s
Blends of poly[(R)-3-hydroxybutyrate] (PHB) with poly(l-lactide acid) (PLLA) were prepared to study the crystallization behavior of PHB in the blends. To investigate the effect of molar mass of PLLA on the crystallization of PHB, two types of PLLA with high and low molecular weight, HPLLA and LPLLA, were used. It was found that the crystallization behavior of PHB in PHB/HPLLA and PHB/LPLLA blends is essentially the same for thicker films, e.g., 1 μm thick films. The crystallization behavior of PHB within PHB/HPLLA and PHB/LPLLA blends in ultrathin films is, however, quite different. For PHB/LPLLA thin films, it was found that crystallization degree of PHB decreases first slightly with increasing LPLLA content, and then the crystallization stops when the weight ratio of PHB (wPHB) decreases to 30 wt %. On the other hand, for the PHB/HPLLA thin films, the crystallization of PHB is inhibited even at extremely high weight ratio of PHB (wPHB ≤ 78 wt %). It was further found that thermal annealing does not enhance crystallization ability of PHB in PHB/HPLLA thin films with wPHB ≤ 78 wt %. Infrared reflection–absorption spectroscopy (IR-RAS) suggested the existence of an intermediate state of PHB. The transition from the intermediate state to crystalline phase is significantly slowed down in the thin film of PHB/HPLLA blend with wPHB ≤ 78 wt %.
Co-reporter:Dr. Zhongjie Ren;Dianming Sun; Huihui Li;Qiang Fu; Dongge Ma; Jianming Zhang; Shouke Yan
Chemistry - A European Journal 2012 Volume 18( Issue 13) pp:4115-4123
Publication Date(Web):
DOI:10.1002/chem.201103684
Abstract
A ladder polysilsesquioxanes with side chain of dibenzothiophene groups (BS-LPSQ) was successfully synthesized. The ladder structure of BS-LPSQ was characterized by MALDI-TOF MS, XRD, and 1H NMR spectroscopy. Differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), atomic force microscopy (AFM), and spectroscopic analyses revealed that the BS-LPSQ has good film-forming ability, high thermal and morphological stability, and good miscibility to the dopant iridium bis(4,6-difluorophenyl)pyridinato-N,C2-picolinate (FIrpic), high triplet energy, and a wide bandgap. In addition, compared with the ringed polysiloxane BS-PSQ phosphorescent host material reported previously, the ladder structure of BS-LPSQ has not only a higher thermal resistance, but also could prevent molecular aggregation and effectively avoid quenching of fluorescence. Thus, the BS-LPSQ may be used as a better host for the blue-light-emitting iridium complex FIrpic. The performance of the electrophosphorescent device, based on the ladder BS-LPSQ as the active layer, is superior to that of ringed BS-PSQ and any other polyhedral oligomeric silsesquioxane (POSS)-based or polymer host materials.
Co-reporter:Min Gao, Zhongjie Ren, and Shouke Yan, Jingru Sun and Xuesi Chen
The Journal of Physical Chemistry B 2012 Volume 116(Issue 32) pp:9832-9837
Publication Date(Web):July 24, 2012
DOI:10.1021/jp3041378
The dependence of phase structure of PLLA/PPC blends on the blend ratio, the heat-treatment temperature and time was investigated by optical microscopy. It is found that, at lower PPC content, e.g., less than 30%, the PLLA crystalline spherulites fill the whole space with the PPC dispersed in the amorphous region of PLLA. No evident phase separation has been observed under optical microscope. When the content of PPC reaches 40%, phase separation takes place. The phase separation of the PLLA/PPC blend happens prior to the crystallization of PLLA. Therefore, the heat-treatment temperature and time are the two most important factors that control the phase structure of the blend. At low heat-treatment temperatures, e.g., lower than 190 °C, the PPC and the amorphous PLLA part compose a continuous phase with the crystalline PLLA domains dispersed in it. When the sample was heat-treated at 200 °C for 5 min, a bicontinuous phase structure was observed. With further increase of the heat-treatment temperature, the crystalline PLLA composes the continuous phase with PPC domains randomly dispersed in it. Similar phase reversal phenomenon has also been observed by heat-treating the samples at 200 °C for different times. It is further confirmed that the crystallization of PLLA in the blends is influenced by the different phase structures. For example, the crystallinity of PLLA in the blend increases with increasing heat-treatment temperature.
Co-reporter:Zhongjie Ren, Rongben Zhang, Yuguang Ma, Feng Wang and Shouke Yan
Journal of Materials Chemistry A 2011 vol. 21(Issue 21) pp:7777-7781
Publication Date(Web):26 Apr 2011
DOI:10.1039/C1JM10290G
A ringed polysiloxane with a side chain of dibenzothiophene groups (BS-PSQ) is successfully synthesized as confirmed by MALDI-TOF MS and 1H-NMR. DSC, TGA, AFM and spectra reveal its good film-forming ability, high thermal and morphological stability, and good miscibility with the dopant FIrpic. In addition, it also has a high triplet energy and a wide band gap. The BS-PSQ may be used as a host for the blue light emitter iridium complex FIrpic. The electrophosphorescent device based on BS-PSQ as the active layer exhibits typical blue emission, and the performance of the device is superior to that of any other POSS-based host material reported and also to some of the small molecular host materials.
Co-reporter:Zhongjie Ren, Zhize Chen, Wenxin Fu, Rongben Zhang, Fangzhong Shen, Feng Wang, Yuguang Ma and Shouke Yan
Journal of Materials Chemistry A 2011 vol. 21(Issue 30) pp:11306-11311
Publication Date(Web):17 Jun 2011
DOI:10.1039/C1JM11087J
A ladder polysilsesquioxane with side chain 3-methyl-1,5-diphenylbenzene groups (Tp-LPSQ) is synthesized successfully and confirmed by the MALDI-TOF MS, 29Si-NMR and 1H-NMR. DSC, TGA, AFM and PL spectra reveal its good film-forming property, high thermal and morphological stability and good miscibility to the dopant FIrpic. In addition, it also shows a high triplet energy and a wide bandgap. Thus Tp-LPSQ may act as a host for the blue light emitting iridium complex FIrpic. The electrophosphorescent device based on Tp-LPSQ as the active layer exhibits typical blue emission and the performance of device is superior to other reported polymeric host materials.
Co-reporter:Zhongjie Ren, Rongben Zhang, Feng Wang and Shouke Yan
Polymer Chemistry 2011 vol. 2(Issue 3) pp:608-613
Publication Date(Web):09 Nov 2010
DOI:10.1039/C0PY00274G
Hydrogen bonds formed in ladder polyphenylsilsesquioxane (Ph-LPSQ)/polyisophthalamide (Cn-PA) composites and their electrospun fibers were studied by ATR FT-IR in detail. It has been found that the peak position of hydrogen bonded N–H stretching vibration in the electrospun composite fibers shifts to higher wavenumber compared to that produced in the composite powders. Moreover, the wavenumber shift increases with increasing electrospinning voltage. This is caused by the transformation of N–H⋯OC hydrogen bonds into N–H⋯OSi2 ones during the electrospinning process. Possible structure models for the composite powders and the electrospun composite fibers were proposed.
Co-reporter:Tianchang Wang, Huihui Li, Feng Wang, Jerold M. Schultz and Shouke Yan
Polymer Chemistry 2011 vol. 2(Issue 8) pp:1688-1698
Publication Date(Web):16 May 2011
DOI:10.1039/C1PY00134E
The morphological features and mechanical properties of PVDF/PBS blends with a variety of blend ratios and under different preparation conditions have been studied by optical and atomic force microscopy, as well as by tensile tests. It was found that, at high PVDF crystallization temperature, a small amount of PBS in the 70/30 PVDF/PBS blends has been expelled into the PVDF spherulite margin areas and interspherulitic regions due to the high diffusion ability of PBS and the slower crystal growth rate of the PVDF at high temperature. Nevertheless, the PBS affects the crystallization of PVDF significantly, which has been revealed by the increase in birefringence of PVDF spherulites of both α and γ types and the increase in band period of the α PVDF spherulites. With increasing PBS content, the increase in birefringence of PVDF spherulites and the increase in band period of the α PVDF spherulites get more evident, reflecting a more efficient influence of PBS on the crystallization of PVDF. In the PBS-rich blends, e.g., in the 40/60 and 30/70 PVDF/PBS blends, the PVDF forms isolated spherulites with large non-crystallizing PBS melt regions, which results in an interspherulitic phase separation with bigger interspherulitic PVDF areas. There is, however, PBS dispersed within the PVDF spherulites. During the crystallization of PBS at low temperature, it was found that the PBS in the interspherulitic and interaspherulitic regions growth in different manner with different growth rates. At lower PVDF crystallization temperatures, the PVDF crystallizes first and fills all the volume in regardless its content in the blends. This leads to the PBS being distributed in the interlamellar or interfibrillar regions of PVDF spherulites only. However, the growth of PBS in banded and non-banded PVDF matrix is different, reflecting the influence of pre-existing PVDF crystals on the crystallization of PBS. Tensile test shows that the deformation behavior depends remarkably on the blend ratio and the crystallization temperature of the PVDF. Such phenomena has been correlated and explained in view of the inner morphological change.
Co-reporter:Haixin Zhou, Shidong Jiang, and Shouke Yan
The Journal of Physical Chemistry B 2011 Volume 115(Issue 46) pp:13449-13454
Publication Date(Web):October 18, 2011
DOI:10.1021/jp205755r
Crystallization of P3HT on highly oriented PE ultrathin films via solution-deposition has been studied by means of optical microscopy, atomic force microscopy, Fourier transform infrared spectroscopy (FTIR), and electron diffraction. The results clearly indicated the occurrence of heteroepitaxy of P3HT on the PE substrate, which results in a parallel alignment of P3HT on the PE substrate. FTIR spectra and electron diffraction analyses demonstrate that molecular chains of P3HT are oriented in the film plane and aligned parallel to the chain direction of PE substrate crystals, while the (100) lattice plane of P3HT is in contact with the PE substrate. The observed epitaxy can be explained in terms of an excellent one-dimensional lattice matching between the interchain distances of PE in the (110) lattice plane and P3HT in the (100) lattice plane. This kind of epitaxial crystallization provides an efficient way for fabricating large area P3HT films with unique oriented structures.
Co-reporter:Xiaoli Sun, Longhai Guo, Harumi Sato, Yukihiro Ozaki, Shouke Yan, Isao Takahashi
Polymer 2011 Volume 52(Issue 17) pp:3865-3870
Publication Date(Web):3 August 2011
DOI:10.1016/j.polymer.2011.06.024
The exact molecular chain orientation of poly(β-hydroxybutyrate) (PHB) in ultrathin films was successfully probed using surface-sensitive, grazing incidence X-ray diffraction techniques. The crystal orientation of spin-coated PHB films was very sensitive to free surface and thermal annealing. In pristine films, the free surface easily exerted its influence on PHB crystallization and caused lamellar orientation with the b-axis perpendicular to the film surface. The effect of the buried interface increased with temperature. With the increase in thermal annealing temperature, the lamellar orientation changed from the b-axis being perpendicular to the film surface to the c-axis becoming perpendicular to the film surface. As film thickness increased, the temperature, at which the lamellae with the b-axes oriented normal to the film surface disappeared, increased. The thickness and temperature dependence of the crystallization behavior of PHB in an ultrathin film could be attributed to the competition between the effects of the free surface and the buried interface.
Co-reporter:Tianchang Wang, Huihui Li, Feng Wang, Shouke Yan, and Jerold M. Schultz
The Journal of Physical Chemistry B 2011 Volume 115(Issue 24) pp:7814-7822
Publication Date(Web):May 19, 2011
DOI:10.1021/jp203680e
The morphology and confined crystallization behavior of poly(butylene succinate) (PBS) in miscible poly(vinylidene fluoride) (PVDF)/PBS blends has been studied using differential scanning calorimetry (DSC) and optical and atomic force microscopy (OM and AFM). It was found that PBS crystal lamellae nucleated and grew confined inside the matrix of PVDF spherulites. Crystallized PBS domains grow with an ellipsoidal outline within PVDF spherulites formed at a relatively high PVDF crystallization temperature (Tc,PVDF), while circular domains, engulfing several PVDF spherulites, are seen when growing in the PVDF spherulites created at lower Tc,PVDF. The growth kinetics of PBS confined in the PVDF matrix was investigated under various conditions. The growth rate of PBS (GPBS) increases with decreasing crystallization temperature and increasing PBS content under a given PVDF crystallization temperature (Tc,VDF). For Tc,PVDF above 145 °C, GPBS decreases with Tc,PVDF for both 50:50 and 30:70 PVDF/PBS blends. However, for Tc,PVDF below 145 °C, 50:50 and 30:70 PVDF/PBS blends exhibit the opposite GPBS trend; that is, GPBS for the 50:50 blend decreases with decreasing Tc,PVDF, while for the 30:70 PVDF/PBS blend GPBS increases with decreasing Tc,PVDF. It is shown that this behavior cannot be associated with the effect of crossing the boundary of smaller PVDF spherulites formed at a lower temperature. Rather, the behavior appears to be related to the interleaving growth of PBS lamellae among PVDF lamellae or between bundles of PVDF lamellae (fibrils), as in situ AFM observation shows. It is found that the interconnectedness of the molten pockets within the PVDF spherulites, which depends on the PVDF crystallization temperature, is an important factor determining the growth kinetics of PBS confined within the PVDF scaffold.
Co-reporter:Xiaoli Sun, Fuwei Pi, Jianming Zhang, Isao Takahashi, Feng Wang, Shouke Yan, and Yukihiro Ozaki
The Journal of Physical Chemistry B 2011 Volume 115(Issue 9) pp:1950-1957
Publication Date(Web):February 14, 2011
DOI:10.1021/jp110003m
The phase transition behavior of poly(butylene adipate) (PBA) crystals in its blends with poly(vinyl phenol) (PVPh) was investigated by infrared (IR) spectroscopy and X-ray diffraction (XRD). The IR and XRD studies indicate that the hydrogen bonding between the C═O group of PBA and the OH group of PVPh developed in the PBA/PVPh blends with the ratios of 80/20 and 50/50 does not influence the solution crystallization behavior of PBA. The phase transition behavior of PBA in the blends is, however, significantly altered by the blending. In the neat PBA, linear changes of the intensities of IR bands at 1077, 930, and 910 cm−1 are observed in the temperature range of 25−47.5 °C followed by an abrupt change corresponding to the occurrence of β-to-α phase transition. In the blends, the accelerated intensity changes of the those IR bands occur before the β-to-α phase transition, which is contributed to the melting of imperfect β-PBA crystals at relatively lower temperature. In addition, the significantly depressed β-to-α phase transition temperature is also identified.
Co-reporter:Wenxin Fu, Chang He, Shidong Jiang, Zhize Chen, Jintao Zhang, Zhibo Li, Shouke Yan, and Rongben Zhang
Macromolecules 2011 Volume 44(Issue 2) pp:203-207
Publication Date(Web):December 28, 2010
DOI:10.1021/ma1025797
A soluble perylenediimide (PDI) bridged ladder polysiloxane (PDI-LPS) was prepared using ladder superstructure (LS) directed dehydration polycondensation. LS was first assembled via synergistic interactions of hydrogen-bonding and π−π stacking of tetrasilanol monomers (M2s) as verified from XRD, 29Si NMR, and VPO characterizations. The ladder regularity of PDI-LPS was confirmed by a narrow half-peak width (Δ) of <1 ppm for SiO2/2 unit in the 29Si NMR spectra. The alignment of ladder chains was also demonstrated from high-resolution transmission electronic microscopy (HR-TEM) observations. We successfully used ladderlike structure to chemically confine PDI cores within one-dimensional polymeric semiconductor. The resulting PDI-LPS not only retained PDI’s optoelectronic properties but also gained enhanced solubility in common organic solvents and improved thermal stability.
Co-reporter:Huihui Li and Shouke Yan
Macromolecules 2011 Volume 44(Issue 3) pp:417-428
Publication Date(Web):January 10, 2011
DOI:10.1021/ma1023457
The dependence of properties on the structure and morphology of semicrystalline polymers offers an effective way to tailor the properties of these materials through crystal engineering. For purposeful control of the structure and morphology, and therefore the physical and mechanical properties, a full understanding of the crystallization habits of polymers under different environments and conditions is essential. This has stimulated a mass of research work on polymer crystallization. Considering that these materials are frequently in contact with some kinds of solid surfaces in a variety of applications, surface-induced crystallization of polymers has attracted considerable attention during the past decades. This Perspective provides the context as to how the solid surface influences the crystallization behavior of polymers and what kinds of unique crystal structure and morphology of the polymers can be fabricated. We hope that this will afford useful information for polymer processing in different application fields and promote the technical development of new methods of preparation of polymeric materials for advanced applications.
Co-reporter:Yu-kuan An;Shi-dong Jiang;Shou-ke Yan 闫寿科
Chinese Journal of Polymer Science 2011 Volume 29( Issue 4) pp:513-519
Publication Date(Web):2011 July
DOI:10.1007/s10118-010-1028-0
The crystalline structure and morphology of the PLA crystallized isothermally from the glassy state on highly oriented PE substrates at 130°C were investigated by means of optical microscopy, AFM and X-ray diffraction. The results indicate that the PE substrate influences the crystallization behavior of PLA remarkably, which leads to the growth of PLA crystals on PE substrate always in edge-on form rather than the twisted lamellar crystals from edge-on to flat-on when crystallizing the PLA on glass surface under the same condition. The edge-on PLA lamellae on the PE substrate are preferentially arranged with their long axes in the chain direction of the PE substrate crystals. It is further demonstrated that except for the different crystal orientation, the PE does not influence the crystalline modification and crystallinity of the PLA.
Co-reporter:Haibo Chang, Qipeng Guo, Deyan Shen, Lin Li, Zhaobin Qiu, Feng Wang, and Shouke Yan
The Journal of Physical Chemistry B 2010 Volume 114(Issue 41) pp:13104-13109
Publication Date(Web):September 24, 2010
DOI:10.1021/jp106995f
It is confirmed that a layer of vacuum-evaporated carbon on the surface of a preoriented ultrathin polymer film can lead to an oriented recrystallization of the polymer film. This has been attributed to a strong fixing effect of vacuum-evaporated carbon layer on the film surface of the polymer. To study the origin of the strong fixing effect of vacuum-evaporated carbon layer on the polymer films, the melting and recrystallization behaviors of the preoriented ultrathin PE film with a vacuum-evaporated carbon layer were studied by using atomic force microscopy, electron diffraction, Fourier transform infrared spectroscopy, and Raman spectroscopy. We found that there exists some extent of chain orientation of carbon-coated polyethylene (PE) preoriented ultrathin film above its melting temperature. These oriented PE chain sequences act as nucleation sites and induce the oriented recrystallization of preoriented PE film from melt. Raman spectroscopy results suggest that new carbon−carbon bonds between the carbon layer and the oriented PE film are created during the process of vacuum carbon evaporation. As a result, some of the PE chain stems are fixed to the coated carbon substrate via covalent bond. Such a bonding has retarded the relaxation of the PE chains at the spot and, therefore, preserves the original orientation of the PE stems at high temperature, which in turn derives the recrystallization of the PE chains in an oriented structure.
Co-reporter:Zhongjie Ren, Ping Xie, Shidong Jiang, Shouke Yan and Rongben Zhang
Macromolecules 2010 Volume 43(Issue 5) pp:2130-2136
Publication Date(Web):February 12, 2010
DOI:10.1021/ma100145j
High molecular weight (Mw) triple-chain ladder polyphenylsiloxane (TCLP) was synthesized by a supramolecular architecture-directed approach. First, a bis(phenyldihydroxysiloxy)dimethoxysilane ladder monomer was self-assembled via hydrogen bonding interactions in acetonitrile/toluene (1:1, v/v) solution to form a ladder superstructure (LS). Then the LS was used as a template to direct the whole polymerization process. Lyophilization and surface-enhanced synchronous growth polycondensation process of the LS gave a ladder dimethoxysiloxy-bridged polyphenylsiloxane (DCLP) with gaseous triethylamine as condensation catalyst. Then DCLP was hydrolyzed to form a triple-chain ladder superstructure (TCLS), which was further converted into the target TCLP via subsequent in situ dehydration condensation. The three ladder entities formed during the polymerization, that is, LS, DCLP, and TCLP, have been well characterized. X-ray diffraction shows two Bragg reflections representing the ladder width and ladder thickness, respectively. 29Si NMR analysis illustrates narrow peaks with the peak width at half-height of 0.5−2.5 ppm for the repeat units of the entities, indicating fine ladder regularity. In addition, an investigation of the dependence of the intrinsic viscosity [η] on molecular weight (Mw) in Mark−Houwink−Sakurada equation gave the exponent factor α = 1.19, suggesting the target TCLP had a semirigid ladder structure. Meanwhile, high-resolution transmission electron microscopy observations showed a regular morphological structure for TCLP with a molecular width of ca. 1.4 nm. This value is quite close to the X-ray diffraction data. Dynamic mechanical analysis experiments also indicated TCLP has high storage modulus and high thermal stability.
Co-reporter:Shidong Jiang, Huihui Li, Claudio De Rosa, Finizia Auriemma and Shouke Yan
Macromolecules 2010 Volume 43(Issue 3) pp:1449-1454
Publication Date(Web):January 8, 2010
DOI:10.1021/ma9023894
Single crystals of syndiotactic poly(propene-co-1-butene) with 1-butene as the rich component have been obtained through ultrathin film growth from the melts. The morphological and structural studies on these single crystals have disclosed the influence of propene units on the crystallization behavior of syndiotactic poly(1-butene) (sPB-1). Bright field electron microscopy shows that incorporating the propene units in the sPB-1 chains influences the crystallization habit of the sPB-1 significantly. For example, the aspect ratio of the single crystals increases with increasing the propene units, resulting in copolymer single crystals more similar to those of the sPP homopolymer. The electron diffraction results indicate that a small amount of propene units, up to 9−10 mol %, does not affect the C-centered chain packing of form I of sPB-1. The propene units are most likely included into the crystalline structure of sPB-1. For much higher propene content, around about 30 mol %, the b/4 shift disorder takes place. Nevertheless, the C-centered chain packing is still the predominant packing scheme in the single crystals of the 1-butene-rich copolymers, even though with substantial amount of disorder.
Co-reporter:Haibo Chang, Jianming Zhang, Lin Li, Zhaohui Wang, Chunming Yang, Isao Takahashi, Yukihiro Ozaki and Shouke Yan
Macromolecules 2010 Volume 43(Issue 1) pp:362-366
Publication Date(Web):December 8, 2009
DOI:10.1021/ma902235f
Studies on the influence of foreign surfaces on the crystallization of polymers have demonstrated that the lamellae of the epitaxial polymer in the contact layer could be several times thicker than those produced by bulk crystallization under the same condition. It is, however, not clear that how far of the polymer melt from the interface can be affected by the foreign surface and how this effect propagates from the interface into the polymer melt. Therefore, the molecular dynamics of PCL during its epitaxy on an oriented PE substrate was studied. The obtained results show that keeping the samples at temperatures above the bulk melting temperature but below the equilibrium melting point of PCL for a period of time leads to the formation of unusual ordered PCL, which melts at much higher temperature than its bulk crystallized counterpart. It was demonstrated that the ordering process propagates from the interface into the PCL melt. For a sufficient time, all of the PCL chains can be organized into the similar ordered structure, which leads to the final epitaxial crystallization of PCL on the PE substrate with extremely broad lamellae thickness.
Co-reporter:Xiaoli Sun, Huihui Li, Xiuqin Zhang, Dujin Wang, Jerold M. Schultz and S. Yan
Macromolecules 2010 Volume 43(Issue 1) pp:561-564
Publication Date(Web):December 2, 2009
DOI:10.1021/ma9019784
Co-reporter:Zhongjie Ren, Xinyu Cao, Ping Xie, Rongben Zhang, Shouke Yan and Yongmei Ma
Chemical Communications 2009 (Issue 27) pp:4079-4081
Publication Date(Web):01 Jun 2009
DOI:10.1039/B904057A
A reactive and purely inorganic high Mw perfect ladder polyhydrosilsesquioxane (H-LPSQ) was first prepared under the direction of two imperative supramolecular architectures: ladder superstructure (H-LS) and donor–acceptor complex (DAC).
Co-reporter:Shidong Jiang, Hualei Qian, Wei Liu, Chunru Wang, Zhaohui Wang, Shouke Yan and Daoben Zhu
Macromolecules 2009 Volume 42(Issue 23) pp:9321-9324
Publication Date(Web):October 29, 2009
DOI:10.1021/ma9019762
Epitaxial crystallization of PTH on highly oriented PE substrate from vapor phase has been achieved. The epitaxial growth of PTH on highly oriented PE substrate leads to the formation of lathlike PTH crystals. The lathlike PTH crystals exhibit well-ordered structure with their long axes preferentially parallel to the chain direction of the PE substrate crystals, while a small part of PTH lathlike crystals aligned with their long axes perpendicular to the chain direction of the PE. Electron diffraction further demonstrates that the epitaxial crystallization of PTH on oriented PE substrate results in an alignment of PTH with the c- and b-axes in the film plane. The c-axis of PTH is oriented either perpendicular, preferentially, or parallel, less frequently, to the PE chain direction. The former originates from a two-dimensional lattice matching, while the latter is based only on a one-dimensional intermolecular matching. The observed epitaxial growth provides an effective way for preparing large area well-arranged PTH films with unique crystalline structure.
Co-reporter:Shidong Jiang, Bin Kong, Wei Han, Peter C. Thüne, Xiaozhen Yang, Joachim Loos, Shouke Yan
Polymer 2009 50(15) pp: 3810-3818
Publication Date(Web):
DOI:10.1016/j.polymer.2009.05.043
Co-reporter:Zhenzhen Zhou, Le Ma, Weiwei Zhen, Xiaoli Sun, Zhongjie Ren, Huihui Li, Shouke Yan
Polymer (24 February 2017) Volume 111() pp:183-191
Publication Date(Web):24 February 2017
DOI:10.1016/j.polymer.2017.01.052
Co-reporter:Huanli Dong ; Shidong Jiang ; Lang Jiang ; Yaling Liu ; Hongxiang Li ; Wenping Hu ; Erjing Wang ; Shouke Yan ; Zhongming Wei ; Wei Xu ;Xiong Gong
Journal of the American Chemical Society () pp:
Publication Date(Web):November 5, 2009
DOI:10.1021/ja907015p
In this paper, we show that well-defined, highly crystalline nanowires of a rigid rod conjugated polymer, a poly(para-phenylene ethynylene)s derivative with thioacetate end groups (TA-PPE), can be obtained by self-assembling from a dilute solution. Structural analyses demonstrate the nanowires with an orthorhombic crystal unit cell wherein the lattice parameters are a ≈ 13.63 Å, b ≈ 7.62 Å, and c ≈ 5.12 Å; in the nanowires the backbones of TA-PPE chains are parallel to the nanowire long axis with their side chains standing on the substrate. The transport properties of the nanowires examined by organic field-effect transistors (OFETs) suggest the highest charge carrier mobility approaches 0.1 cm2/(V s) with an average value at ∼10−2 cm2/(V s), which is 3−4 orders higher than that of thin film transistors made by the same polymer, indicating the high performance of the one-dimensional polymer nanowire crystals. These results are particular intriguing and valuable for both examining the intrinsic properties of PPEs polymer semiconductors and advancing their potential applications in electronic devices.
Co-reporter:Zhongjie Ren, Xinyu Cao, Ping Xie, Rongben Zhang, Shouke Yan and Yongmei Ma
Chemical Communications 2009(Issue 27) pp:NaN4081-4081
Publication Date(Web):2009/06/01
DOI:10.1039/B904057A
A reactive and purely inorganic high Mw perfect ladder polyhydrosilsesquioxane (H-LPSQ) was first prepared under the direction of two imperative supramolecular architectures: ladder superstructure (H-LS) and donor–acceptor complex (DAC).
Co-reporter:Dianming Sun, Yongxiu Li, Zhongjie Ren, Martin R. Bryce, Huihui Li and Shouke Yan
Chemical Science (2010-Present) 2014 - vol. 5(Issue 8) pp:NaN3245-3245
Publication Date(Web):2014/06/13
DOI:10.1039/C4SC01068J
Electrochemical polymerization of 3-methylthiophene on highly oriented poly(vinylidene fluoride) (PVDF) film was achieved by cyclic voltammetry to yield well-ordered poly(3-methylthiophene) (P3MT) thin films with anisotropic structural and conductivity properties. The conductivity of P3MT along the direction perpendicular to the chain direction of PVDF, after electrochemical dedoping, is 59 ± 3 S cm−1, while that along the PVDF chain direction is 1.2 ± 0.4 S cm−1. The high conductivity of the P3MT is attributed to the well-ordered structure with its flat-on single crystals as confirmed by electron diffraction and Reflection Absorption Infra-red Spectroscopy (RAIRS). The data are consistent with P3MT chains aligned with π–π stacking perpendicular to the chain direction of the PVDF substrate. Epitaxial electropolymerization is an unusual method of preparing highly ordered thin films of organic semiconductors.
Co-reporter:E Wang, Dianming Sun, Huihui Li, Xiaoli Sun, Junteng Liu, Zhongjie Ren and Shouke Yan
Journal of Materials Chemistry A 2016 - vol. 4(Issue 28) pp:NaN6760-6760
Publication Date(Web):2016/06/28
DOI:10.1039/C6TC01892K
Trinitrotoluene (TNT) and dinitrotoluene (DNT) as the most common explosives are considered to be harmful to the environment and humans. Therefore, the detection of these explosives has been attracting more and more attention. And easily prepared polymer materials with high sensing performance are still in demand. In this study, two silicon-containing polymers, PCzSiO and PCzSiPh, are employed to detect the explosives TNT and DNT. PCzSiPh shows a better performance and the quenching efficiency of PCzSiPh films in TNT and DNT vapor can reach 91.0 ± 0.3% and 94.4 ± 0.3%, respectively, due to their loose molecular chain structure. Furthermore, the fluorescence quenching of PCzSiPh in TNT and DNT is little dependent on the thickness of the film. And the PCzSiPh films show good reversibility, good film-forming ability and high thermal and morphological stability, which suggest their potential application in the coating of detection devices.
Co-reporter:Bing He, Zhongjie Ren, Chenze Qi, Shouke Yan and Zhaohui Wang
Journal of Materials Chemistry A 2015 - vol. 3(Issue 24) pp:NaN6177-6177
Publication Date(Web):2015/05/14
DOI:10.1039/C5TC01046B
A one-step synthesis of a large-area and highly nitrogen-doped graphene (NG) membrane with few defects derived from poly 4-vinyl pyridine (P4VP) has been reported. The synthesis temperature has been optimized by Raman spectroscopy and X-ray photoelectron spectroscopy (XPS). With this approach, a large-area of more than 80% single-layer NG membrane with a nitrogen content of 6.37% can be obtained. Scanning electron microscopy (SEM), atomic force microscopy (AFM), Raman mapping-mode, optical microscopy (OM) and transmission electron microscopy (TEM) analyses reveal that the resultant NG is a flat, continuous, uniform and monolayered graphene membrane with a large area and a well-ordered crystalline structure. The electrical measurement confirms the typical n-type field-effect transistors (FETs) for NG both in air and vacuum, and the electron mobility can reach as high as 365 cm2 V−1 s−1, much higher than those of NGs previously reported. In addition, the transmittance and sheet resistance of NG correlates well with a monolayered structure and semiconducting properties, which also makes it a candidate of transparent electrode for various optoelectronic devices.
Co-reporter:Ce Mi, Ruize Tan, Dianming Sun, Zhongjie Ren, Xiaoli Sun and Shouke Yan
Journal of Materials Chemistry A 2015 - vol. 3(Issue 39) pp:NaN10255-10255
Publication Date(Web):2015/09/18
DOI:10.1039/C5TC02195B
In this study, two new donor–acceptor alternate copolysiloxanes containing carbazole and PDI derivatives pendants (PCzMSi-alt-PDISi and PCzPhSi-alt-PDISi) were prepared. The two copolysiloxanes showed the resistor type memory behavior. The memory devices based on PCzMSi-alt-PDISi and PCzPhSi-alt-PDISi exhibited nonvolatile flash memory characteristics, with an ON/OFF current density ratio of 103 and low threshold voltages (less than 1 V). As far as we know, it is the first nonvolatile flash memory device reported with the lowest threshold voltage based on the copolymer due to high flexibility of Si–O bonds. The conformation change from the regiorandom and regioregular alignments and the charge transfer interactions between pendent carbazole donor and PDI acceptor moieties as well as the unstable CT complex explain their memory characteristics. Our results open a new way to prepare the low-energy cost flash memory devices with the donor–acceptor pendent polysiloxanes.
Co-reporter:Bing He, Zhongjie Ren, Shouke Yan and Zhaohui Wang
Journal of Materials Chemistry A 2014 - vol. 2(Issue 30) pp:NaN6055-6055
Publication Date(Web):2014/05/15
DOI:10.1039/C4TC00481G
In this study, well-ordered multilayer graphene has been obtained via highly oriented polyethylene (OPE) films. Optical microscopy (OM), atomic force microscopy (AFM), Raman laser spectroscopy, scanning electron microscopy (SEM) and transmission electron microscopy (TEM) results indicated that the obtained graphene films were continuous and uniform in lattice orientation. Optical and electrical characterization of the prepared graphene revealed that the thin films are stable in air and exhibit better optical and electrical properties than that obtained from non-oriented polyethylene (nOPE).
Co-reporter:Dianming Sun, Xiaokang Zhou, Huihui Li, Xiaoli Sun, Yonghao Zheng, Zhongjie Ren, Dongge Ma, Martin R. Bryce and Shouke Yan
Journal of Materials Chemistry A 2014 - vol. 2(Issue 39) pp:NaN8284-8284
Publication Date(Web):2014/09/03
DOI:10.1039/C4TC01467G
A universal hybrid polymeric host (PCzSiPh) for blue and deep blue phosphors has been designed and synthesized by incorporating electron-donating carbazole as pendants on a polytetraphenylsilane main chain. The polymer PCzSiPh (4) has a wide bandgap and high triplet energy (ET) because of the tetrahedral geometry of the silicon atom in the tetraphenylsilane backbone. The distinct physical properties of good solubility, combined with high thermal and morphological stability give amorphous and homogenous PCzSiPh films by solution processing. As a result, using PCzSiPh as host with the guest iridium complex TMP-FIrpic gives blue phosphorescent organic light-emitting diodes (PhOLEDs) with overall performance which far exceeds that of a control device with poly(vinylcarbazole) (PVK) host. Notably, FIrpic-based devices exhibit a maximum external quantum efficiency (EQE) of 14.3% (29.3 cd A−1, 10.4 lm W−1) which are comparable to state-of-the-art literature data using polymer hosts for a blue dopant emitter. Moreover, the versatility of PCzSiPh extends to deep blue PhOLEDs using FIr6 and FCNIrpic as dopants, with high efficiencies of 11.3 cd A−1 and 8.6 cd A−1, respectively.
Co-reporter:Dianming Sun, Zhongjie Ren, Martin R. Bryce and Shouke Yan
Journal of Materials Chemistry A 2015 - vol. 3(Issue 37) pp:NaN9508-9508
Publication Date(Web):2015/08/14
DOI:10.1039/C5TC01638J
Organic light emitting diodes (OLEDs) are currently receiving much attention for applications in new generation full-colour flat-panel and flexible displays and as sources for low energy solid-state lighting. Arylsilanes and siloxanes have been extensively studied as components of OLEDs, mainly focusing on optimizing the physical and electronic properties of the light-emitting layer and other functional layers within the OLED architecture. Arylsilanes and siloxanes display the advantages of good solubility in common organic solvents and excellent resistance to thermal, chemical and irradiation degradations. In this review, we summarize the recent advances in the utilization of arylsilanes and siloxanes as fluorophore emitters, hosts for phosphor emitters, hole and exciton blocking materials, and as electron and hole transporting materials. Finally, perspectives and challenges related to arylsilanes and siloxanes for OLED applications are proposed based on the reported progress and our own opinions.
Co-reporter:Dianming Sun, Qiang Fu, Zhongjie Ren, Wei Li, Huihui Li, Dongge Ma and Shouke Yan
Journal of Materials Chemistry A 2013 - vol. 1(Issue 34) pp:NaN5350-5350
Publication Date(Web):2013/07/03
DOI:10.1039/C3TC31108B
The efficient host materials containing carbazole moieties linked to the backbone of polysiloxane through a phenyl bridge have been synthesized and characterized. They exhibit good film forming ability, high thermal decomposition temperatures and suitable glass transition temperatures, so as to form stable amorphous states. Moreover, the silicon–oxygen linkage disrupts their conjugation and results in a sufficiently high triplet energy level (3.0 eV). Iridium bis(4,6-difluorophenyl)pyridinato-N,C2 picolinate (FIrpic)-based devices using them as hosts show good overall performance with low efficiency roll-off. The device using PCzMSi as the host demonstrates the best performance with a maximum current efficiency of 22.8 cd A−1, a maximum power efficiency of 9.4 lm W−1 and a maximum external quantum efficiency of 11.9% at a practical luminance of 1165 cd m−2. Even at a brightness of 5000 cd m−2 level, the external quantum efficiency (EQE) still remains as high as 10%, suggesting a gentle roll-off of device efficiency at high current density. In addition, typically, the host PCzMSi film displays good mechanical performance by a nanoindentation technique to meet the practical application. These results demonstrate that the design of polysiloxane-based host materials is a promising approach to realize high performance solution-processed blue phosphorescent polymer light emitting diodes (PhPLEDs).
Co-reporter:Zhongjie Ren, Dianming Sun, Jianming Zhang and Shouke Yan
Journal of Materials Chemistry A 2012 - vol. 22(Issue 36) pp:NaN18846-18846
Publication Date(Web):2012/08/02
DOI:10.1039/C2JM34379G
Reduced graphene oxide (rGO) sheets covalently functionalized with n-type tetrachloroperylene diimide (PDI) and oligomeric PDI have been prepared by a two-step approach. Firstly, graphene oxide (GO) was modified by an amidation reaction with 3-aminopropyldimethylethoxylsilane or 3-aminopropyldiethoxylmethylsilane, during which GO was reduced thermally. They then react with the silanol modified PDI by dehydration condensation to obtain PDI and oligomeric PDI modified rGO (rGO–PDI and rGO–(PDI)n). The successful preparation of rGO–PDI and rGO–(PDI)n were confirmed by FTIR, Raman, X-ray photoelectron spectroscopy and XRD. The morphologies of rGO–PDI and rGO–(PDI)n sheets were studied using AFM. It was found that surface morphologies and height of rGO–PDI and rGO–(PDI)n sheets are dependent on the solvents used for casting due to differences in the solubility of PDI. Moreover, the fluorescence emission spectrum of rGO–PDI and rGO–(PDI)n shows strong fluorescence quenching and blue shift, especially in ethanol. Current sensing atomic force microscopy (CSAFM) indicated that the rGO–PDI composite shows quite different electric conductivity and optical properties with grafting efficiency and different solvents used for casting. Significantly, the electronic conductivity of rGO–(PDI)n increased by 2–3 orders of magnitude compared to rGO–PDI.
Co-reporter:Zhongjie Ren, Rongben Zhang, Yuguang Ma, Feng Wang and Shouke Yan
Journal of Materials Chemistry A 2011 - vol. 21(Issue 21) pp:NaN7781-7781
Publication Date(Web):2011/04/26
DOI:10.1039/C1JM10290G
A ringed polysiloxane with a side chain of dibenzothiophene groups (BS-PSQ) is successfully synthesized as confirmed by MALDI-TOF MS and 1H-NMR. DSC, TGA, AFM and spectra reveal its good film-forming ability, high thermal and morphological stability, and good miscibility with the dopant FIrpic. In addition, it also has a high triplet energy and a wide band gap. The BS-PSQ may be used as a host for the blue light emitter iridium complex FIrpic. The electrophosphorescent device based on BS-PSQ as the active layer exhibits typical blue emission, and the performance of the device is superior to that of any other POSS-based host material reported and also to some of the small molecular host materials.
Co-reporter:Zhongjie Ren, Zhize Chen, Wenxin Fu, Rongben Zhang, Fangzhong Shen, Feng Wang, Yuguang Ma and Shouke Yan
Journal of Materials Chemistry A 2011 - vol. 21(Issue 30) pp:NaN11311-11311
Publication Date(Web):2011/06/17
DOI:10.1039/C1JM11087J
A ladder polysilsesquioxane with side chain 3-methyl-1,5-diphenylbenzene groups (Tp-LPSQ) is synthesized successfully and confirmed by the MALDI-TOF MS, 29Si-NMR and 1H-NMR. DSC, TGA, AFM and PL spectra reveal its good film-forming property, high thermal and morphological stability and good miscibility to the dopant FIrpic. In addition, it also shows a high triplet energy and a wide bandgap. Thus Tp-LPSQ may act as a host for the blue light emitting iridium complex FIrpic. The electrophosphorescent device based on Tp-LPSQ as the active layer exhibits typical blue emission and the performance of device is superior to other reported polymeric host materials.
Co-reporter:Liwei Ye, Huihui Li, Zhaobin Qiu and Shouke Yan
Physical Chemistry Chemical Physics 2015 - vol. 17(Issue 11) pp:NaN7580-7580
Publication Date(Web):2015/02/13
DOI:10.1039/C4CP05910G
The melt–recrystallization behavior of α-iPP fibers embedded in an amorphous HIPS matrix has been studied by means of optical microscopy. The amorphous HIPS serving as a supporter of iPP fibers does not become involved in the nucleation and crystallization process of the molten highly oriented iPP fibers. It also does not provide any birefringence under the optical microscope with crossed polarizers. This enables the study of orientation-induced β-iPP crystallization through a control of the melting status of the fibers. Through melting the fibers at different temperatures above 175 °C and subsequent recrystallization, some β-iPP crystals were always produced. The content of the β-iPP crystal depends strongly on the melting temperature and melting time of the iPP fibers. It was confirmed that melting the iPP fibers at relatively lower temperature, e.g. 176 °C, less amount of β-iPP crystals were observed. The content of β-iPP crystal enhances first with increasing melting temperature and then decreases with further increase of the fiber melting temperature. The β-iPP crystallization is found to be most favorable upon melting the fibers at 178 °C for 2 min. This demonstrates the requirement of a certain chain or chain segment orientation for generating β-iPP crystallization on the one hand, while higher orientation of the iPP chains or chain segments encourages the growth of iPP crystals in the α-form on the other hand. This has been further confirmed by varying the melting time of the fiber at different temperatures, since relaxation of the iPP molecular chains at a fixed temperature is time dependent. Moreover, the complete transformation of α-iPP fibers in some local places into β-iPP crystals implies that the αβ-transition may not be required for the orientation-induced β-iPP crystallization.
Co-reporter:Tingjie Zhang, Zhongjie Ren, Xiaoli Sun and Shouke Yan
Physical Chemistry Chemical Physics 2015 - vol. 17(Issue 35) pp:NaN23073-23073
Publication Date(Web):2015/08/14
DOI:10.1039/C5CP04228C
Perylenebisimide (PBI) nanowires and nanosheets with high chemical and mechanical stability are prepared by a simple way. Firstly, a PBI-based organosilane precursor PBI-Si(OEt)3 was synthesized. Its nanostructures were then assembled by a solvent-exchange method. The nanostructures could be adjusted by assembling in different solvents. The obtained nanostructures were finally fixed by acetic acid vapor treatment through polycondensation of the triethoxysilyl groups in the precursors. After polycondensation, the nanostructures hardly change and they become insoluble in common solvents. Moreover, the conductivity of the polycondensed nanowires and nanosheets are ca. 35–40 times than that of polycondensed spin-coated PBI-Si(OEt)3 film by current sensing atomic force microscopy (CSAFM).
Co-reporter:Shujing Zhang, Xiaoli Sun, Zhongjie Ren, Huihui Li and Shouke Yan
Physical Chemistry Chemical Physics 2015 - vol. 17(Issue 48) pp:NaN32231-32231
Publication Date(Web):2015/11/18
DOI:10.1039/C5CP06076A
The miscibility of poly(propylene carbonate) (PPC) and poly(3-hydroxybutyrate) (PHB) blends was analyzed by differential scanning calorimetry (DSC) and polarized optical microscopy (POM). The results indicated that the blends are immiscible at most blending compositions, and a miscible blend can be obtained when the PHB content is as low as 10 wt%. The morphology of the PPC/PHB (70/30) blend film was characterized by POM, scanning electron micrography (SEM) and Fourier transform infrared spectroscopy (FTIR), and the development of a PPC-top and microporous PHB-bottom bilayer structure can be revealed. Different from the normal case, phase separation can take place on the normal direction of the film surface in the PPC/PHB (70/30) blend at 190 °C, attributed to the different surface energies of the two components. The continuous segregation of PPC to the top-layer can result in the crystallization of PHB at the bottom layer and conversely promote the complete development of a bilayer structure. Since the isotropic PPC layer is transparent with no birefringence, the PHB spherulite with a microporous structure at the bottom layer can be observed directly by POM. Moreover, the microporous structure of the bottom layer should be attributed to the solution cast procedure. Thus, some unique crystalline patterns may be created in the demixed crystalline/amorphous polymer blends, which differ greatly from those obtained from the miscible blend systems.
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![Benzo[lmn][3,8]phenanthroline-1,3,6,8(2H,7H)-tetrone, 2,7-bis(2,2,3,3,4,4,4-heptafluorobutyl)-](/data/chemimg/136100/268724-95-4.png)
![Benzo[lmn][3,8]phenanthroline-1,3,6,8(2H,7H)-tetrone, 2,7-bis(2,2,3,3,4,4,4-heptafluorobutyl)-](/data/chemimg/136100/268724-95-4_b.png)
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![benzo[1,2-b:4,5-c']bisthiophene-4,8-dione](http://img.cochemist.com/ccimg/33600/33527-22-9_b.png)
![Poly[oxy(1-oxo-1,6-hexanediyl)]](http://img.cochemist.com/ccimg/25300/25248-42-4.png)
![Poly[oxy(1-oxo-1,6-hexanediyl)]](http://img.cochemist.com/ccimg/25300/25248-42-4_b.png)
![Poly[oxy-1,4-butanediyloxy(1,6-dioxo-1,6-hexanediyl)]](http://img.cochemist.com/ccimg/25000/24936-97-8.png)
![Poly[oxy-1,4-butanediyloxy(1,6-dioxo-1,6-hexanediyl)]](http://img.cochemist.com/ccimg/25000/24936-97-8_b.png)
![3,3'-(5'-(3-(Pyridin-3-yl)phenyl)-[1,1':3',1''-terphenyl]-3,3''-diyl)dipyridine](http://img.cochemist.com/ccimg/921300/921205-03-0.png)
![3,3'-(5'-(3-(Pyridin-3-yl)phenyl)-[1,1':3',1''-terphenyl]-3,3''-diyl)dipyridine](http://img.cochemist.com/ccimg/921300/921205-03-0_b.png)
![2,4,8,10-tetra(tert-butyl)-6-hydroxy-12H-dibenzo[d,g][1,3,2]dioxaphosphocin 6-oxide, sodium salt](http://img.cochemist.com/ccimg/85300/85209-91-2.png)
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![Poly[oxycarbonyloxy(methyl-1,2-ethanediyl)]](http://img.cochemist.com/ccimg/37300/37248-85-4.png)
![Poly[oxycarbonyloxy(methyl-1,2-ethanediyl)]](http://img.cochemist.com/ccimg/37300/37248-85-4_b.png)
![Poly[oxy[(1R)-1-methyl-3-oxo-1,3-propanediyl]]](http://img.cochemist.com/ccimg/31800/31759-58-7.png)
![Poly[oxy[(1R)-1-methyl-3-oxo-1,3-propanediyl]]](http://img.cochemist.com/ccimg/31800/31759-58-7_b.png)
![[chloro(diethoxy)methyl]silane](http://img.cochemist.com/ccimg/18200/18157-20-5.png)
![[chloro(diethoxy)methyl]silane](http://img.cochemist.com/ccimg/18200/18157-20-5_b.png)
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![Poly[oxy[(1S)-1-methyl-2-oxo-1,2-ethanediyl]]](http://img.cochemist.com/ccimg/26200/26161-42-2.png)
![Poly[oxy[(1S)-1-methyl-2-oxo-1,2-ethanediyl]]](http://img.cochemist.com/ccimg/26200/26161-42-2_b.png)
