Co-reporter:Weidong Zhang, Bingjie Zhang, Demei Yu, Gang He
Science Bulletin 2017 Volume 62, Issue 13(Volume 62, Issue 13) pp:
Publication Date(Web):15 July 2017
DOI:10.1016/j.scib.2017.05.020
Co-reporter:Guowei Lv, Shihu Zhang, Guolong Wang, Jinyou Shao, Hongmiao Tian, Demei Yu
Reactive and Functional Polymers 2017 Volume 111() pp:44-52
Publication Date(Web):February 2017
DOI:10.1016/j.reactfunctpolym.2016.12.005
•A soluble polypyrrole with low molecular weight and favorable thin film-forming ability.•Newtonian fluid and a high electrical conductivity of its dilute solution in chloroform.•By doping this polypyrrole, an insulating photoresist is transformed into a conductive photoresist.•A larger reduction in the contact angle of electrowetting on dielectrics.•Rapid fabrication of the pillar arrays with higher aspect ratio.A methacryl ethyl-functionalized soluble polypyrrole was designed and prepared by chemical oxidative polymerization for rapid fabrication of high-aspect-ratio pillar arrays. The chemical structures of the pyrrole derivative and the corresponding polypyrrole were characterized by FTIR and 1H NMR. The polypyrrole with a weight-average molecular weight (Mw) of 7376 exhibits good solubility in several organic solvents, favorable thin film-forming ability and two UV–Vis absorption peaks at 280 and 380 nm in tetrahydrofuran solution. The dilute chloroform solution of the polypyrrole is a Newtonian fluid with a low viscosity and shows a significant increase in the electrical conductivity with increasing the polypyrrole content. Moreover, an insulating photoresist can be transformed into a conductive photoresist by doping this polypyrrole. Electrowetting driven structure formation experiments have confirmed that the conductive photoresist can fulfill rapid fabrication of higher-aspect-ratio pillar arrays compared with the insulating photoresist.
Co-reporter:Junwen Ren, Demei Yu, Lihua Feng, Guolong Wang, Guowei Lv
Composites Part A: Applied Science and Manufacturing 2017 Volume 98(Volume 98) pp:
Publication Date(Web):1 July 2017
DOI:10.1016/j.compositesa.2017.03.014
A hierarchical nanocable structure was fulfilled by grafting poly(glycidyl methacrylate) from single walled carbon nanotubes (PGMA-SWCNTs) via activators regenerated by electron transfer-atom transfer radical polymerization (ARGET-ATRP). It was found that SWCNTs were parallelly separated by the grafted PGMA brushes in the nanocables. To investigate the advantages of nanocable architecture, a composite film was prepared through filtrating the uniform solution of PGMA-SWCNTs nanocables. The dielectric properties dependent on frequency and temperature revealed that high dielectric constants, high impedance and low dielectric loss were simultaneously achieved for the PGMA-SWCNTs film. Meanwhile, thermal conductive analysis showed that the PGMA-SWCNTs film possessed a high thermal conductivity. The unique nanocable structure and the excellent interfacial interaction between PGMA and SWCNTs were believed to be the critical causes for the high performance of the nanocomposite.
Co-reporter:Guolong Wang, Demei Yu, Ajit D. Kelkar, Lifeng Zhang
Progress in Polymer Science 2017 Volume 75(Volume 75) pp:
Publication Date(Web):1 December 2017
DOI:10.1016/j.progpolymsci.2017.08.002
The rapidly developing technique of electrospinning has gained surging research interest since the 1990s due to its capability of yielding continuous fibers with diameters down to the nanometer scale. Despite enormous efforts devoted to explore applications of electrospun nanofibers, such as separation, catalysis, nanoelectronics, sensors, energy conversion/storage, and biomedical utilization, there are limited attempts to employ these nanofibers for reinforcement in polymer composites. Electrospun nanofibers, however, possess comprehensive advantages not typically shared by other nanoscale composite fillers/reinforcing agents, such as continuity, diverse material choice, controlled diameter/structure, possible alignment/assembly, mass production capability and so forth. Therefore electrospun nanofibers have great potential as promising reinforcement fillers for next-generation polymer composites. This is a comprehensive and state-of-the-art review of the latest advances made in development of electrospun nanofiber reinforced polymer composite materials with intention to stimulate interests in both academia and industry.
Co-reporter:Guowei Lv, Shihu Zhang, Jinyou Shao, Guolong Wang, Hongmiao Tian, Demei Yu
Reactive and Functional Polymers 2017 Volume 118(Volume 118) pp:
Publication Date(Web):1 September 2017
DOI:10.1016/j.reactfunctpolym.2017.06.014
A leaky dielectric photoresist was designed and prepared for rapid fabrication of high-aspect-ratio micro-/nanostructures via electrohydrodynamic patterning (EHDP). The rheological behavior and electrical properties of the photoresists were systematically investigated, since the structure formation in EHDP essentially originates from the flow and deformation of the polymeric film actuated by an applied electric field. It is found that the photoresists exhibit the suitable rheological behavior with a low viscosity of 2.4–157.7 mPa s, controllable electrical conductivity of 5.0 × 10− 6 − 7.2 × 10− 4 S m− 1, as well as high homogeneity, minor surface tension of about 30 mN·m− 1, favorable wettability and film-forming property on substrate and an extremely large reduction in the contact angle (down to 1.64°) of electrowetting on dielectric (EWOD). The EHDP results have shown that a higher electrical conductivity of the photoresists can lead to a higher filling height, a smaller characteristic wavelength and a shorter patterning time, while a lower viscosity can also lead to a shorter patterning time, which is accordance with the theoretical prediction. In addition, the patterning time of the photoresists cannot be too short because the following rapid ripening and coalescence of the formed microstructure will damage the high fidelity of the final pillar arrays.The electrohydrodynamic microstructures with either higher aspect ratio or smaller feature size can be fabricated instantaneously at ambient temperature via fine modulating the rheological behavior and the electrical conductivity of a designed UV-curable leaky dielectric fluid.Download high-res image (158KB)Download full-size image
Co-reporter:Qiong Tian, Demei Yu, Kaiming Zhu, Guohe Hu, Lifeng Zhang, Yuhang Liu
Journal of Colloid and Interface Science 2016 Volume 473() pp:44-51
Publication Date(Web):1 July 2016
DOI:10.1016/j.jcis.2016.03.063
Multi-hollow particles have drawn extensive research interest due to their high specific areas and abundant inner voids, whereas their convenient synthesis still remains challenging. In this paper, we report a simple and convenient method based on seeded swelling polymerization to prepare the multi-hollow microspheres with enclosed surfaces and compartmentalized voids using monodisperse poly (styrene-co-sodium 4-vinylbenzenesulfonate) microspheres as seed particles. A formation mechanism of the multi-hollow structure was proposed involving the processes of water absorption, coalescence and stabilization of water domains, immobilization of multi-hollow structure, and coverage of surface dimples. The influencing parameters on the morphology of the microspheres, including weight ratio of sodium 4-vinylbenzenesulfonate to styrene in the seed particles, dosage of the swelling monomer and the crosslinking agent were systematically investigated. The internal structure of the resultant microspheres could be tuned from solid to multi-hollow by controlling over these parameters. Multi-hollow microspheres with compartmentalized chambers, smooth surfaces and narrow size distributions were obtained as a result.
Co-reporter:Guolong Wang, Demei Yu, Ram V. Mohan, Spero Gbewonyo, Lifeng Zhang
Composites Science and Technology 2016 Volume 129() pp:19-29
Publication Date(Web):6 June 2016
DOI:10.1016/j.compscitech.2016.04.006
Electrospun glass nanofibers (EGNFs) are emerging fillers to improve mechanical properties of polymer matrix composite materials. However, questions concerning their reinforcing effectiveness in comparison with other nanoscale fillers such as glass/silica nanoparticles (GNPs) are still to be answered because reinforcing mechanisms for conventional fiber reinforced polymer composites might not be applicable at distinctive nanometer scale. Herein a comparative study on reinforcing effect of EGNFs and their conventional counterpart GNPs was carried out for the first time. Four types of glass nanofillers, including pristine EGNFs and GNPs as well as amino surface-functionalized EGNFs and GNPs were investigated to make epoxy matrix nanocomposites at ultra-low loading level (≤0.5 wt%). Mechanical properties of these glass nanofiller reinforced epoxy composites were investigated and corresponding reinforcing and toughening mechanisms at nanometer scale were discussed. Due to shape factor (aspect ratio), EGNFs demonstrated much more pronounced reinforcing and toughening effectiveness and completely outperformed GNPs in all cases despite much lower specific surface area. This research provided meaningful data to fully understand the merit of EGNFs as reinforcing filler in polymer nanocomposites and paved the road for designing and modeling next-generation polymer matrix composite materials.
Co-reporter:Chunliang Yao, Zhen Xue, Meng Lian, Xianbin Xu, Jiang Zhao, Guijiang Zhou, Yong Wu, Demei Yu, Wai-Yeung Wong
Journal of Organometallic Chemistry 2015 Volume 784() pp:31-40
Publication Date(Web):15 May 2015
DOI:10.1016/j.jorganchem.2014.05.003
•New IrIII complexes based on 2-phenylimidazo[1,2-a]pyridine-type ligands.•The photophysical and electroluminescent features of the complexes.•These complexes show balanced charge-transporting features.New iridium(III) cyclometalated complexes based on 2-phenylimidazo[1,2-a]pyridine-type ligands were synthesized and their photophysical, electrochemical and electroluminescent (EL) properties were investigated. The detailed insight into the characters of the emissive excited states was obtained by frontier molecular orbital analysis. These metal complexes exhibit very balanced charge transporting ability for both kinds of charge carriers, which can furnish decent EL performance in the phosphorescent organic light-emitting devices (PHOLEDs) with peak luminance of 15491 cd m−2 at ca. 13.5 V, external quantum efficiency of 6.81%, luminance efficiency of 34.74 cd A−1, and power efficiency of 17.54 lm W−1. These results not only provide a better understanding of the inherent characters of IrIII phosphors with phenylimidazo[1,2-a]pyridine units, but also valuable information on future molecular design of triplet emitters with unique electronic features for high-performance PHOLEDs.New phenylimidazo[1,2-a]pyridine-based phosphorescent emitters of iridium have been developed. The balanced charge-transporting features for both kinds of charge carriers can bring about decent device performance, revealing the great potential of the phenylmidazo[1,2-a]pyridine-based IrIII phosphorescent materials.
Co-reporter:Shihu Zhang, Guowei Lv, Guolong Wang, Kaiming Zhu, Demei Yu, Jinyou Shao, Yanzhou Wang, Yuhang Liu
Journal of Photochemistry and Photobiology A: Chemistry 2015 Volume 309() pp:30-36
Publication Date(Web):15 August 2015
DOI:10.1016/j.jphotochem.2015.04.023
•An oligopyrrole derivative (OMDPP) with unique structure was prepared.•OMDPP had an average polymerization degree of 3 with a low polydispersity of 1.09.•The formation mechanism of OMDPP was discussed.•The fluorescence properties of OMDPP solution were investigated.A soluble oligopyrrole derivative (OMDPP) was prepared based on a bipyrrole monomer 2-methyl-1,3-di(1H-pyrrol-1-yl) propan-1-one (MDPP) using chemical oxidation method. The characterization of the chemical structure indicated that OMDPP was mainly generated from the coupling of the pyrrole ring attached to the methylene group in the monomer. Our results also proved that OMDPP exhibited good solubility and film-forming ability. The fluorescence properties of OMDPP solutions were then characterized, and green emissions were observed in the wavelength range of 550–564 nm in a variety of solvents under the excitation wavelength of 467 nm. The research of solvatochromic behavior of OMDPP revealed that the electron donating-accepting property of the solvent possibly have greater impact on the Stokes shift of OMDPP solution compared with the polarity of the solvent. Additionally, the concentration (from 5*E-6 g/ml to 8*E-4 g/ml) and the excitation wavelength (287–507 nm) also exhibited obvious influences on the emission spectra of the OMDPP solution, which were investigated in detail.
Co-reporter:Hongbin Hou, Demei Yu, and Guohe Hu
Langmuir 2015 Volume 31(Issue 4) pp:1376-1384
Publication Date(Web):January 14, 2015
DOI:10.1021/la5032784
Four kinds of silver ion-imprinted particles (Ag-IIPs) with different morphologies were prepared by the surface ion-imprinting technology (SIIT) and were used for the selective removal and concentration of silver ions from wastewater. The favorable adsorptivity and selectivity of Ag-IIPs for Ag+ were confirmed by a series of adsorption experiments at a suitable pH value. The adsorption mechanism was elucidated by analyzing the adsorption isotherms, adsorption thermodynamics, and adsorption kinetics systematically. The Ag+ adsorption onto the Ag-IIPs was well-described by the Langmuir isotherm model, and it was likely to be a monolayer chemical adsorption. This conclusion was also confirmed by the thermodynamic parameters. Moreover, the adsorption kinetics indicated that the adsorption rate would be controlled jointly by the intraparticle diffusion and the inner surface adsorption process, and the latter process was generally associated with the formation and breaking of chemical bonds. Finally, the effects of different morphologies of the Ag-IIPs for Ag+ adsorption were also investigated. In aqueous solution, the adsorptivity of the Ag+ ion-imprinting single-hole hollow particles (Ag-IISHPs) for Ag+ was highest (80.5 mg g–1) because of a specific morphology that features a single hole in the shell. In an oil–water mixture, Ag+ in the water phase could be adsorbed efficiently by the Ag+ ion-imprinting Janus hollow particles (Ag-IIJHPs), with emulsifiability originating from the Janus structure.
Co-reporter:Shihu Zhang
The Journal of Physical Chemistry C 2015 Volume 119(Issue 32) pp:18707-18718
Publication Date(Web):July 21, 2015
DOI:10.1021/acs.jpcc.5b03883
As a green oxidant, H2O2 can be used to induce the polymerization of pyrrole. This approach avoids the issue of metal residue in the polymer caused by metal oxidants, whereas the reaction efficiency is low and the corresponding reaction mechanism not clear. In this study, uniform polypyrrole (PPy) nanoparticles were prepared using H2O2 as an oxidant under UV irradiation in the presence of polyvinylpyrrolidone (PVP). The morphology characterization indicated that the spherical PPy nanoparticles were capped by a PVP shell. Through the investigation of reaction process, it was found that the photolysis of H2O2 led to the formation of hydroxyl radicals, which then initiated the oxidative polymerization of pyrrole. The coalescence of small PPy particles formed nanoparticles which were stabilized by PVP. The effects of several reaction conditions on the polymerization rate and the size distribution of nanoparticles were investigated in detail, including radiation intensity (0–30 W), temperature (0–50 °C), and the concentrations of PVP (5–20 g/L), H2O2 (0.06–0.6 M), H2SO4 (0–0.22 M), and the monomer pyrrole (0.03–0.2 M), respectively. UV-catalytic preparation of PPy nanoparticles induced by H2O2 is an effective and environmentally friendly approach, which could be expected to be extended to other conductive polymers.
Co-reporter:Xin Xu, Zhaoyang Fan, Shujiang Ding, Demei Yu and Yaping Du
Nanoscale 2014 vol. 6(Issue 10) pp:5245-5250
Publication Date(Web):28 Feb 2014
DOI:10.1039/C3NR06736J
MoS2 nanosheet@TiO2 nanotube hybrid nanostructures were successfully prepared by a facile two-step method: prefabrication of porous TiO2 nanotubes based on a sol–gel method template against polymeric nanotubes, and then assembly of MoS2 nanoclusters that consist of ultrathin nanosheets through a solvothermal process. These hybrid nanostructures were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive X-ray (EDX) spectroscopy, X-ray diffraction (XRD) and Brunauer–Emmett–Teller (BET) analysis. When evaluated as an electrode material for lithium ion batteries, the results of the electrochemical test show that the unique MoS2 nanosheet@TiO2 nanotube hybrid nanostructures exhibit outstanding lithium storage performances with high specific capacity and excellent rate capability. The smart architecture of the MoS2 nanosheet@TiO2 nanotube hybrid nanostructures makes a prominent contribution to the excellent electrochemical performance.
Co-reporter:Xin Xu, Bitao Dong, Shujiang Ding, Chunhui Xiao and Demei Yu
Journal of Materials Chemistry A 2014 vol. 2(Issue 32) pp:13069-13074
Publication Date(Web):17 Jun 2014
DOI:10.1039/C4TA02003K
In this paper, we report a facile approach to the synthesis of one-dimension (1D) hierarchical NiCoO2 nanosheets (NSs)@amorphous CNT composites based on the templates and carbon source of polymeric nanotubes (PNTs). Importantly, these sulfonated PNTs can also be used to prepare many other functional 1D metal oxides@amorphous CNT nanostructures, such as TiO2, SnO2, CoO and NiO, etc. Due to the outstanding nanostructures and the synergistic effects of the NiCoO2 NSs and amorphous CNTs, an ultrahigh discharge capacity of 1309 mA h g−1 is delivered by the NiCoO2@CNT composites, even after 300 cycles at a current density of 400 mA g−1. The favorable improvements of the NiCoO2 based lithium-ion batteries (LIBs) reported in this work illustrate that the 1D amorphous carbon matrix offers significant benefits for high-capacity metal oxide anode nanomaterials.
Co-reporter:Xin Xu, Guorui Yang, Jin Liang, Shujiang Ding, Chengli Tang, Honghui Yang, Wei Yan, Guidong Yang and Demei Yu
Journal of Materials Chemistry A 2014 vol. 2(Issue 1) pp:116-122
Publication Date(Web):15 Oct 2013
DOI:10.1039/C3TA12863F
TiO2@SnO2 nanosheets@nanotubes heterostructures were successfully prepared by a facile two-step method: prefabricated SnO2@PNT coaxial nanocables based on the in situ growth of SnO2 in the sulfonated gel matrix of polymeric nanotubes, and then the assembly of TiO2 nanoclusters that consist of ultrathin nanosheets through a solvothermal process. These heterostructures were characterized for the morphological, structural and optical properties by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), UV-visible (UV-vis) and diffuse reflectance spectroscopy (DRS). The photocatalytic investigations showed that the TiO2@SnO2 heterostructures possessed enhanced photocatalytic efficiency in the photodegradation of Rhodamine B (RhB) and photocatalytic H2 evolution from water splitting under ultraviolet (UV) light irradiation, compared with the pristine TiO2 nanosheets, SnO2 nanotubes, the mechanically mixed two samples and P25. The enhanced photocatalytic performance can be ascribed to the beneficial microstructure and synergistic effects of coupled TiO2@SnO2 nanosheets@nanotubes heterostructures.
Co-reporter:Xin Xu, Han Zhou, Shujiang Ding, Jun Li, Beibei Li, Demei Yu
Journal of Power Sources 2014 Volume 267() pp:641-647
Publication Date(Web):1 December 2014
DOI:10.1016/j.jpowsour.2014.05.077
•NiCoO2 nanosheets nanotubes are prepared against polymeric nanotube template.•The products show superior specific capacitance and cycling stability.•The smart nanostructures are favorable for fast ion and electron transfer.Hierarchical NiCoO2 nanosheets nanotubes are successfully prepared by a mild solution method based on the template of polymeric nanotubes (PNT) followed by a thermal annealing treatment. The microstructure and chemical composition of NiCoO2 nanosheets nanotubes are characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), Brunauer–Emmett–Teller (BET) analyzer, X-ray diffraction (XRD) and Thermogravimetric analysis (TGA). When evaluated as an electrode material for supercapacitors, the results of electrochemical test show that the unique NiCoO2 nanosheets nanotubes exhibit relatively high specific capacitance of 1468, 1352, 1233, 1178, 1020 and 672 F g−1 at the discharge current densities of 2, 4, 8, 10, 20 and 40 A g−1, respectively. They also reveal an excellent cycling stability of 99.2% retention after 3000 cycles at 10 A g−1. The smart nanostructures of the NiCoO2 nanosheets nanotubes make a prominent contribution to the excellent electrochemical performance.Hierarchical NiCoO2 nanotubes comprised ultrathin nanosheets show enhanced electrochemical performance.
Co-reporter:Yan Gao, Yanzhou Wang, Xin Xu, Kun Ding and Demei Yu
RSC Advances 2014 vol. 4(Issue 109) pp:63719-63724
Publication Date(Web):19 Nov 2014
DOI:10.1039/C4RA10680F
In this work, a kind of polypyrrole (PPy) layer–PPy nanowire–TiO2 nanotube brush-like composite has been successfully prepared. Highly ordered and free-standing TiO2 nanotube arrays were prefabricated via an anodizing method, pyrrole was then filled and polymerized in the nanotube arrays through an electrochemical deposition route to form a nanowire-in-tube structure together with a PPy layer outside. The morphology of the as-prepared hybrid nanostructure was observed by scanning electron microscope (SEM), the PPy filling in the TiO2 nanotube was confirmed by Fourier transform infrared spectroscopy (FTIR) and Raman spectroscopy. When investigated as an anode material for supercapacitors, the as-obtained PPy/TiO2 could deliver a capacity of 446 F g−1 at a current density of 15 A g−1 even after 1000 cycles, which is much higher than individual TiO2 nanotubes and PPy, respectively. The smart nanostructure of the PPy/TiO2 nanocomposites makes a prominent contribution to the excellent electrochemical performance.
Co-reporter:Yan Gao, Kun Ding, Xin Xu, Yanzhou Wang and Demei Yu
RSC Advances 2014 vol. 4(Issue 77) pp:40898-40898
Publication Date(Web):04 Sep 2014
DOI:10.1039/C4RA90004A
Correction for ‘PPy film/TiO2 nanotubes composite with enhanced supercapacitive properties’ by Yan Gao et al., RSC Adv., 2014, 4, 27130–27134.
Co-reporter:Xin Xu, Jin Liang, Han Zhou, Shujiang Ding and Demei Yu
RSC Advances 2014 vol. 4(Issue 7) pp:3181-3187
Publication Date(Web):02 Dec 2013
DOI:10.1039/C3RA45038D
Hierarchically tubular structures comprised NiO nanosheets were successfully prepared through a mild solution route based on the template of polymeric nanotubes (PNT) followed by a thermal annealing treatment. The microstructure and chemical composition of NiO nanosheets nanotubes are investigated by SEM, TEM, HRTEM, SAED and XRD. The Brunauer–Emmett–Teller (BET) specific surface area of this sample is calculated to be 98 m2 g−1 and the majority of pores have a size in the range of 2–10 nm. The thermal behavior of Ni-precursor@PNT was studied by TGA and the weight fraction of NiO nanosheets nanotubes obtained by calcination is measured to be 57.0%. The specific capacitance of the unique NiO nanosheets nanotubes is 588 F g−1 at the end of 1000 cycles when the charge–discharge current density is 3 A g−1, leading to only 5.2% capacity loss. In addition, the NiO nanotubes coating by relatively sparse and thin nanosheets possess better electrochemical properties. The specific capacitance is 960 F g−1 at the end of 1000 cycles when the charge–discharge current density is 10 A g−1, leading to only 1.2% capacity loss. Broadly, the as-obtained NiO nanosheets nanotubes reveal relatively high capacitance and remarkable cycling stability in virtue of the hollow, porous, flaky and tubular nanostructures.
Co-reporter:Yan Gao, Kun Ding, Xin Xu, Yanzhou Wang and Demei Yu
RSC Advances 2014 vol. 4(Issue 52) pp:27130-27134
Publication Date(Web):11 Jun 2014
DOI:10.1039/C4RA03014A
In this paper, a film-on-tube PPy/TiO2 composite composed of polypyrrole (PPy) and well-aligned TiO2 nanotube array is reported. Pyrrole is polymerized on the top of TiO2 nanotubes by a two-step anodic oxidation. The morphology and microstructure of these composites are characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), Brunauer–Emmett–Teller (BET) and infrared spectroscopy (FT-IR). The electrochemical performance of the PPy/TiO2 composite is determined by cyclic voltammetry and charge–discharge measurement. It indicates that these film-on-tube composites take advantage of the high electrochemical activity of TiO2 and polypyrrole, the high electronic conductivity of PPy, and the large specific surface area of ordered TiO2 nanotubes. These merits together with the elegant synergy between TiO2 and PPy lead to a good specific capacitance of 459 F g−1 at a current density of 5 A g−1 and excellent cycling stability with capacitance retention of 92.6% after 1000 charge–discharge cycles. The high capacitance as well as excellent cycling stability makes this film-on-tube composite promising as an anode material for supercapacitors.
Co-reporter:Shihu Zhang, Guolong Wang, Guowei Lv, Demei Yu, Yucheng Ding
Synthetic Metals 2014 Volume 195() pp:185-192
Publication Date(Web):September 2014
DOI:10.1016/j.synthmet.2014.06.006
•A monomer 2-methyl-1,3-di(1H-pyrrol-1-yl)propan-1-one (MDPP) was synthesized.•The soluble polymer of MDPP (PMDPP) was obtained by the chemical polymerization.•The polymerization mechanism of MDPP was discussed.•The fluorescence measurements were carried out on PMDPP solutions.A unique dipyrrole monomer 2-methyl-1,3-di(1H-pyrrol-1-yl)propan-1-one (MDPP) was synthesized and the corresponding branched polymer (PMDPP) with the molecular weight (Mw) of 2416 was obtained by the chemical polymerization. The molecular structures of MDPP and PMDPP were characterized by FTIR and NMR. It was found that the polymerization of MDPP was accomplished on the pyrrole ring which is attached to the carbonyl group. The resulting polymer had an amorphous structure and could be dissolved in many organic solvents. The fluorescence measurements were carried out on PMDPP solutions, which emitted the green light in the range of 556–574 nm under the excitation of 467 nm depending on the solvents. It is interesting that the Stokes shift of the PMDPP solution was more sensitive to the electron donor–acceptor properties of solvent rather than the polarity of solvent. Notably, the maximum emission wavelength (λmaxem) of the PMDPP solution showed a red shift from 556 nm to 586 nm with the increase of PMDPP concentration from 1.80 × E−5 g/ml to 6.314 × E−4 g/ml in THF, and it exhibited a remarkable dependence on the excitation wavelength in the range of 327–507 nm, which led to a gradual red shift of the λmaxem from 510 nm to 584 nm.
Co-reporter:Hongbin Hou, Demei Yu, Qiong Tian, and Guohe Hu
Langmuir 2014 Volume 30(Issue 7) pp:1741-1747
Publication Date(Web):2017-2-22
DOI:10.1021/la404808x
As compared to the traditional solid Janus particles, the hollow Janus particles have inspired growing interests due to their diverse potential applications. Herein, the novel hollow Janus particles with elephant trunk-like and acorn-like shapes were prepared by seed emulsion polymerization. In contrast to traditional template methods, the hollow structure was obtained during the preparation by one-step swelling method. The shapes and internal structures of hollow Janus particles were confirmed, and the compositions were identified too. Some critical influences on the morphology control were investigated, that is, the surface modification, the amount of surfactant, and cross-linking agent concentrations. It was inferred that the balance of hydrophilicity and hydrophobicity and the effective phase separation were important for preparing the hollow Janus particles with tailored shapes. Finally, amphiphilic properties of hollow Janus particles were demonstrated by emulsifying oil–water mixture.
Co-reporter:Xin Xu, Jin Liang, Han Zhou, Dongmei Lv, Fuxin Liang, Zhenglong Yang, Shujiang Ding and Demei Yu
Journal of Materials Chemistry A 2013 vol. 1(Issue 9) pp:2995-2998
Publication Date(Web):17 Jan 2013
DOI:10.1039/C3TA01372C
Uniform SnO2 nanotubes with a mesoporous shell were successfully prepared by calcination of SnO2@polymeric nanotubes. The SnO2 nanotubes possess enhanced lithium storage performance compared with SnO2 hollow spheres and SnO2 nanoparticles owing to the unique structure of mesoporous shell, open ends and hollow interior.
Co-reporter:Chao Min, Demei Yu, Jingyu Cao, Guolong Wang, Lihua Feng
Carbon 2013 Volume 55() pp:116-125
Publication Date(Web):April 2013
DOI:10.1016/j.carbon.2012.12.017
A simple strategy for the preparation of composites with high dielectric constant and thermal conductivity was developed through a typical interface design. Graphite nanoplatelets (GNPs) with a thickness of 20–50 nm are fabricated and homogeneously dispersed in the epoxy matrix. A high dielectric constant of more than 230 and a high thermal conductivity of 0.54 W/mK (a 157% increase over that of pure epoxy) could be obtained for the composites with a lower filler content of 1.892 vol.%. The dielectric constant still remains at more than 100 even in the frequency range of 105–106 Hz. When loaded at 2.703 vol.%, GNP/epoxy composites have a dielectric constant higher than 140 in the frequency range of 102–104 Hz and a high thermal conductivity of 0.72 W/mK, which is a 240% increase over that of pure epoxy. The high dielectric constant and low loss tangent are observed in the composite with the GNPs content of 0.949 vol.% around 104 Hz. It is believed that high aspect ratio of GNPs and oxygen functional groups on their basal planes are critical issues of the constitution of a special interface region between the GNPs and epoxy matrix and the high performance of the composites.
Co-reporter:Guangwen Wu, Demei Yu
Progress in Organic Coatings 2013 Volume 76(Issue 1) pp:107-112
Publication Date(Web):January 2013
DOI:10.1016/j.porgcoat.2012.08.018
A low infrared-emissivity coating was prepared using modified Al powder and polyurethane as metallic pigment and adhesive. Al powder was coated with polyethylene wax by the flux-capping method to reduce the emissivity and gloss of the coating. The surface morphology and chemical composition of pure and modified Al powders were characterized by scanning electron microscopy and X-ray diffraction. The infrared emissivity of the product was measured by an infrared emissometer. The influences of the modified Al powder content, substrate material, coating thickness, and aging time on infrared emissivity were systematically investigated. The results indicate that modified Al powder decreases not only the gloss of the coating, but also its emissivity within the wavelength range of 8–14 μm. The polyethylene wax/Al composites have a homogenous sheet structure at 30 wt.% Al content, and a lower infrared emissivity. The optimum content of modified Al powder is around 18 wt.%. The coating exhibits a lower emissivity value and excellent optical properties. The infrared emissivity of the composite coating significantly increases with increased thickness, and approaches a constant value when the thickness is more than 80 μm. Accelerated aging test results show that with increased aging time, the coating with modified Al powder has a better aging resistance and lower infrared emissivity than that with pure Al powder.Highlights► The Al powder was coated with polyethylene wax via a flux-capping method. ► Characterization of polyethylene wax/Al composites. ► The low infrared emissivity coating was prepared by using modified Al powder. ► The modified Al powder decreases the gloss and infrared emissivity of the composite coating.
Co-reporter:Xiusheng Guo;Jingshen Wu;Chao Min;Rongnan Guo
Polymer Engineering & Science 2013 Volume 53( Issue 2) pp:370-377
Publication Date(Web):
DOI:10.1002/pen.23277
Abstract
Multiwall carbon nanotubes (MWNTs) were modified by three methods, namely, oxidizing the tubes and opening both ends, filling the tubes with Ag, and grafting the tubes with hexamethylene diamine. Modified MWNTs/epoxy composites were prepared by melt-mixing epoxy resin with the tubes. Transmission electron microscope images showed that the modified MWNTs can be dispersed in the epoxy matrix homogeneously. The dielectric behaviors and mechanical properties of the composites were investigated. The dielectric and mechanical properties of the modified MWNTs/epoxy composites were considerably improved compared with those of the epoxy matrix. The tensile strengths of the Ag-filled, opened, and grafted MWNTs composites at the same filler content of 1.1 wt% were higher by ∼30.5%, 35.6%, and 27.4%, respectively, than that of neat epoxy. The Izod notched impact strength of the grafted MWNTs/epoxy composite with filler content of 1.1 wt% was approximately four times higher than that of neat epoxy. A dielectric constant of ∼150 of the composite with 1.1 wt% Ag-filled nanotubes was observed in the low-frequency range, which was ∼40 times higher than that of the epoxy matrix. The proper modification of nanotubes provides a way to improve the properties of the polymer-based composites. POLYM. ENG. SCI., 2013. © 2012 Society of Plastics Engineers
Co-reporter:Xiaobing Hu and Demei Yu
RSC Advances 2012 vol. 2(Issue 16) pp:6570-6575
Publication Date(Web):14 May 2012
DOI:10.1039/C2RA20093G
A serials of organo-soluble transition metal–DABDT coordination polymers were successfully synthesized by the coordination of transition metal ions and DABDT. These coordination polymers were characterized by FTIR, TGA, XRD, UV-Vis spectroscopy, fluorescence spectroscopy, TEM, and vibrational sample magnetometry. Results showed that DABDT coordinated transition metal ions by its amino and sulfydryl groups. The coordination polymers of Co–DABDT, Ni–DABDT, Cu–DABDT and Zn–DABDT exhibited crystal or semi-crystal characteristics, while Fe–DABDT was almost amorphous. The synthesized coordination polymers were soluble in the mixed solvent of DMF and DMSO (volume ratio, 1:1). The main UV-Vis absorptions of the as-synthesized transition metal–DABDT coordination polymers were below 400 nm in the ultraviolet region. These coordination polymers emitted cyan light in the DMF and DMSO mixed solution, especially for Zn–DABDT, which emitted obviously stronger cyan light than the other coordination polymers. Fe–DABDT exhibited superparamagnetic character in the approximate range of −5000 G to +5000 G and simple paramagnetic character in the other fields. Co–DABDT and Ni–DABDT followed simple paramagnetic behavior. TEM analysis showed that Ni–DABDT were porous nanospheres with an average diameter of about 69 nm. The rigid molecules of Ni–DABDT arrayed in parallel in the coordination polymer sphere. And Co–DABDT also showed a lamellar structure. The rigid coordination polymer molecules arrayed in parallel due to the formation of hydrogen bond between the –SH and –NH2 groups of adjacent molecular chains in the same plane. And the arrangement between different molecular layers was stacked layer upon layer on account of the π–π stacking of the coordination polymer chains. The solubility of the prepared coordination polymers enabled us to carry out a first-time study on their photophysical behavior. What's more, this is the first time to report the planar and lamellar structure of the transition metal-DABDT coordination polymers through TEM analysis.
Co-reporter:XiaoBing Hu
Macromolecular Chemistry and Physics 2012 Volume 213( Issue 7) pp:
Publication Date(Web):
DOI:10.1002/macp.201290022
Co-reporter:XiaoBing Hu
Macromolecular Chemistry and Physics 2012 Volume 213( Issue 7) pp:738-746
Publication Date(Web):
DOI:10.1002/macp.201100651
Abstract
A series of hyperbranched poly(p-phenylene benzobisthiazole)s (HBPBZTs) are synthesized by solution polycondensation of 2,5-diamino-1,4-benzenedithiol dihydrochloride (DABDT, A2 monomer) and 1,3,5-benzene-tricarboxylic acid (BTA, B3 monomer). Their structure changes depending on the feed molar ratios (A2:B3). The addition of DABDT and BTA (3:2) yielded HBPBZT with stoichiometry equivalent carboxyl and o-aminothiophenol end groups. By adding DABDT and BTA (1:1), carboxyl-terminated HBPBZT is prepared. When the ratio of DABDT and BTA is 9:4, amino and sulfydryl-terminated HBPBZT is obtained. These polymers are amorphous and exhibit good thermal stability. They are soluble in some common polar aprotic solvents. The HBPBZTs exhibit strong blue light in methansulfonic acid and in DMF solution. The type of solvent has a strong influence on optical properties of the HBPBZTs solution.
Co-reporter:Shan Wang, Demei Yu, Yi Huang, Jinchan Guo, Yongsheng Wei
Materials Science and Engineering: B 2011 Volume 176(Issue 3) pp:271-275
Publication Date(Web):25 February 2011
DOI:10.1016/j.mseb.2010.11.007
A pollution-free method to synthesize polyurethane (PU) was used. PU/CdS nanocomposite films were synthesized by simulating bio-mineralization process. The factors that affect the hydrothermal stability and fluorescence properties of the films were studied. Further, the sensing properties of the nanocomposite films to Ag(I) ions in water were systematically investigated. A scanning electron microscopy observation showed that the sizes of the CdS particles are around 60 nm, and the particles are evenly doped within the PU films. The fluorescence emission of nanocomposite films has been found to be very sensitive to the presence of Ag(I) ions, and a small amount of Ag(I) ions makes the emissions increase dramatically. The emission is hardly affected by other common ions in water except chloride and sulfate through their precipitation effects on Ag+ ions. The films are predicted to have the potential to be developed into excellent sensing films for Ag(I) ions in water.
Co-reporter:Guohe Hu, Demei Yu
Materials Science and Engineering: A 2011 528(15) pp: 5177-5183
Publication Date(Web):
DOI:10.1016/j.msea.2011.03.071
Co-reporter:Guohe Hu;Honglu Liang;Chao Min
Polymer Science, Series B 2011 Volume 53( Issue 3-4) pp:
Publication Date(Web):2011 April
DOI:10.1134/S1560090411040038
Two novel aliphatic amine-containing dimethacrylate monomers were synthesized from the ringopening reaction of hexamethylene diamine and ethylenediamine with glycidyl methacrylate. The UV-curable and heat-curable formulations were prepared with amine-containing dimethacrylate and active diluents. The curing process was controlled by Fourier transform infrared analysis. The mechanical, physical, and thermal characterizations of the UV-cured films and the UV-heat-cured films were investigated. Thermo-gravimetric analysis of the cured films revealed that the thermo-oxidative stability of the UV-heat-cured films was higher than that of the UV-cured samples. An increase in the cross-linker content caused an increase both in tensile strength and in the elongation values of the UV-heat-cured films. It was also found that the water absorption capacities and gel content of the UV-heat-cured dimethacrylated films depended on the amount of the active diluents.
Co-reporter:Honglu Liang
Polymer Engineering & Science 2011 Volume 51( Issue 9) pp:1757-1762
Publication Date(Web):
DOI:10.1002/pen.21962
Abstract
Silver/carbon (Ag/C) nanocables were obtained in the presence of cetyltrimethylammonium bromide (CTAB) under hydrothermal conditions in order to modify epoxy resin. Nanocable is a nanocomposite of nanowire (core) wrapped with one or more outer layers (shell). Scanning electron microscopy and energy-dispersive X-ray spectroscopy proved that nanocables consist of a silver nanowire core and a carbon outer shell. The (Ag/C)/epoxy composites were prepared by compounding Ag/C nanocables and epoxy resin. An investigation of the thermal, mechanical, and dielectric properties of these composites showed that the thermal stability and dielectric constant of the composites were enhanced. Interestingly, the breakdown strength of the composites at room temperature increased. Normally, breakdown strength decreases when conducting fillers are added. Fracture morphology of the (Ag/C)/epoxy composite also showed increased toughness. The relationship between the properties and microstructure of the composite was discussed in detail to explain the mechanism behind the change in material properties. POLYM. ENG. SCI., 2011. © 2011 Society of Plastics Engineers
Co-reporter:Wanqin Wang, Demei Yu, Feng Tian
Journal of Luminescence 2010 Volume 130(Issue 3) pp:494-497
Publication Date(Web):March 2010
DOI:10.1016/j.jlumin.2009.10.020
Photoluminescence of a novel polypyrrole based on N-vinylpyrrole was systematically observed in organic solutions. The polymer, which has a unique molecular structure, exhibited good photoluminescence in organic solutions. The emission peak of the polymer exhibited one strong green emission band at around 510 nm in common organic solutions. The maximum fluorescence quantum yield of the polymer was found to be 0.16 in NMP solution with fluorescein as standard. At the same concentration, the photoluminescence intensity increased in the order of CHCl3, THF, DMSO, CH2Cl2 and NMP. The photoluminescence spectrum had a slight red shift as the polarity of the solvents increased. The photoluminescence intensity also increased with the polarity of the solvent, except DMSO. This is because of its hygroscopicity in air and its viscosity. In THF solutions, the photoluminescence intensity increased until the concentration reached a certain weight percent (3.0×10−2 wt.%) and then decreased with higher concentrations. This was most likely due to quenching in the aggregate phase. Furthermore, iron ion was a quencher in the DMSO solution. In a mixed solvent system of DMSO and water, water showed a typical quenching effect.
Co-reporter:Shan Wang
Journal of Applied Polymer Science 2010 Volume 118( Issue 2) pp:733-739
Publication Date(Web):
DOI:10.1002/app.32496
Abstract
Cross-linked chitosans synthesized by the inverse emulsion cross-link method were used to investigate adsorption of three metal ions [Cd(II), Pb(II), and Ag(I)] in an aqueous solution. The chitosan microsphere, was characterized by FTIR and SEM, and adsorption of Cd(II), Pb(II), and Ag(I) ions onto a cross-linked chitosan was examined through analysis of pH, agitation time, temperature, and initial concentration of the metal. The order of adsorption capacity for the three metal ions was Cd2+ > Pb2+ > Ag+. This method showed that adsorption of the three metal ions in an aqueous solution followed the monolayer coverage of the adsorbents through physical adsorption phenomena and coordination because the amino (NH2) and/or hydroxy (OH) groups on chitosan chains serve as coordination sites. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Co-reporter:Wenying Zhou
Journal of Applied Polymer Science 2010 Volume 118( Issue 6) pp:3156-3166
Publication Date(Web):
DOI:10.1002/app.32442
Abstract
Microsized aluminum/epoxy resin composites were prepared, and the thermal and dielectric properties of the composites were investigated in terms of composition, aluminum particle sizes, frequency, and temperature. The results showed that the introduction of aluminum particles to the composites hardly influenced the thermal stability behavior, and decreased Tg of the epoxy resin; moreover, the size, concentration, and surface modification of aluminum particles had an effect on their thermal conductivity and dielectric properties. The dielectric permittivity increased smoothly with a rise of aluminum particle content, as well as with a decrease in frequency at high loading with aluminum particles. While the dissipation factor value increased slightly with an increase in frequency, it still remained at a low level. The dielectric permittivity and loss increased with temperature, owing to the segmental mobility of the polymer molecules. We found that the aluminum/epoxy composite containing 48 vol % aluminum-particle content possessed a high thermal conductivity and a high dielectric permittivity, but a low loss factor, a low electric conductivity, and a higher breakdown voltage. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Co-reporter:Guohe Hu, Demei Yu, Jing Zhang, Honglu Liang
Colloids and Surfaces A: Physicochemical and Engineering Aspects 2010 Volume 356(1–3) pp:78-83
Publication Date(Web):5 March 2010
DOI:10.1016/j.colsurfa.2009.12.035
Micron-sized hollow polymer particles and hollow particles with a single hole in the surface were prepared using seeded polymerization in the presence of n-octanol. The influence of the reaction time on polymer morphology, the content of the cross-linking agent divinylbenzene (DVB), and the amount of n-octanol was discussed. The hollow particles prepared in the present study were characterized by optical microscopy (OM) and scanning electron microscopy (SEM). A single hole was observed in the shell of the hollow particles prepared by the same seeded polymerization with a shorter swelling time and activities. The mechanism of single-hole hollow morphology formation proposed that phase separation occurred between the shell and the core at the polymerization stage. The relatively small diameter of the shell was fixed in polymerization under the shorter swelling time and activities resulted in the formation of the single-hole structure.
Co-reporter:Chao Min
Polymer Engineering & Science 2010 Volume 50( Issue 9) pp:1734-1742
Publication Date(Web):
DOI:10.1002/pen.21698
Abstract
Very thin graphite nanosheets are obtained using an ultrasonic irradiation method, and epoxy/graphite nanosheet composites with different filler content are fabricated using the diglycidylether of bisphenol A epoxy matrix. An investigation of structural characteristics and mechanical and dielectric properties of the nanocomposites is carried out. SEM micrographs shows that the thickness of a single layer graphite nanosheet is about 20 nm whereas FTIR studies indicates that the surfaces of the graphite nanosheets are enriched with hydroxyl and carbonyl groups. The dielectric constants of the composites are increased with increases in graphite nanosheet content lower than 3.5 wt%, and are still higher than 100 in the high frequency range with 3.5 wt% graphite filler content. The tensile strength and storage modulus of the composites increase with increasing nanosheet concentration. These epoxy/graphite nanosheet composites, which show both high dielectric constant and toughness, could have potential application in embedded capacitor technology. POLYM. ENG. SCI., 50:1734–1742, 2010. © 2010 Society of Plastics Engineers
Co-reporter:Yun-Chuan Xie;De-Mei Yu;Chao Min;Xiu-Sheng Guo;Wei-Tao Wan;Jing Zhang;Hong-Lu Liang
Journal of Applied Polymer Science 2009 Volume 112( Issue 6) pp:3613-3619
Publication Date(Web):
DOI:10.1002/app.29741
Abstract
Composites of an expanded graphite/diglycidyl ether of bisphenol A (DGEBA) were prepared by a simple melt blending method, and their dielectric and mechanical properties were investigated. During observations of fractured surfaces of the composites, the graphite sheets were seen to be homogeneously dispersed in the epoxy matrix. Moreover, the composites presented an enhanced dielectric constant (∼ 180) and a low loss factor (∼ 0.05) at 50 Hz, suggesting their potential suitability for embedded dielectric applications. The enhanced dielectric constant can be explained by the percolation theory and the relatively low loss factor was attributed to strong interfacial interactions between the polymer molecules and the OH/COOH groups of the expanded graphite, which constrained the orientational polarization of the polarons. Furthermore, dynamic mechanical analysis of the composites showed a restricted macromolecular relaxation and improved mechanical properties. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Co-reporter:Honglu Liang;Yunchuan Xie;Chao Min;Jing Zhang;Guohe Hu
Polymer Engineering & Science 2009 Volume 49( Issue 11) pp:2189-2194
Publication Date(Web):
DOI:10.1002/pen.21466
Abstract
Nano-Ag particles stabilized by a hyperbranched polymer (HBP) template were prepared for modifying the epoxy resin. The effects of preparation condition on the size and size distribution of Ag colloidal particles were studied. The Ag@HBP particles were then compounded with the epoxy resin to obtain the Ag@HBP/epoxy composites and the mechanical and dielectric properties of these composites were investigated. Dynamic mechanical analysis results show that the composites have higher loss factors than does the unmodified epoxy resin, which indicate better dissipation of mechanical energy and hence better shock or impact resistance. Fracture morphology of the composite shows a toughness feature. From the dielectric test results, the breakdown strength and dielectric constant of the composites at room temperature are increased, which can be explained by the Coulomb block effect. POLYM. ENG. SCI., 2009. © 2009 Society of Plastics Engineers
Co-reporter:Wanqin Wang, Demei Yu, Feng Tian
Synthetic Metals 2008 Volume 158(17–18) pp:717-721
Publication Date(Web):October 2008
DOI:10.1016/j.synthmet.2008.04.016
A novel polymer constituted of N-substituted pyrrole was synthesized by chemical oxidative polymerization from N-vinylpyrrole monomer. The structure of the resulting polymer was characterized by FT-IR, 1H NMR and element analysis. The results indicated that the polymer was comprised of two chains, i.e. α-coupled polypyrrole and polyethylene, and the two chains were found to have the same average degree of polymerization. The investigation of the solubility showed that the polymer was soluble in common organic solvents and could be cast into thin films from a chloroform solution. Interestingly, the polymer displayed strong optical absorption in the visible region and exhibited photoluminescence as determined by UV–vis and fluorescence spectrum analysis.
Co-reporter:Wei-Tao Wan;De-Mei Yu;Long-Biao Huang;Yun-Chuan Xie;Xiu-Sheng Guo;Jing Zhang
Macromolecular Chemistry and Physics 2008 Volume 209( Issue 10) pp:1056-1064
Publication Date(Web):
DOI:10.1002/macp.200800015
Co-reporter:Weitao Wan;Jian He;Yunchuan Xie;Longbiao Huang;Xiusheng Guo
Journal of Applied Polymer Science 2008 Volume 107( Issue 2) pp:1020-1028
Publication Date(Web):
DOI:10.1002/app.26102
Abstract
Epoxy/core-shell particle blends were prepared using a diglycidylether of bisphenol A epoxy and acrylics-type core-shell particles. The impact strength of the blends was tested, and the result showed that the epoxy was greatly toughened with optimum core-shell particle content. Meanwhile, the dielectric properties of both epoxy and its blends were investigated using a broadband dielectric analyzer. It was found that the dielectric constant of the epoxy blends with lower core-shell particle content were less than that of the epoxy in the investigated frequency range, while the dielectric loss was less than that of the neat epoxy over a low frequency range, even for the epoxy blends with the optimum core-shell particle content. The dielectric breakdown strength of the epoxy blends at room and cryogenic temperature were also investigated. To identify the primary relationship of the above properties and structure of the epoxy blends, the microstructure of the core-shell particle and the morphology of the samples were observed by transmission electron microscopy and scanning electron microscopy. It was considered that these epoxy/core-shell particle blends with improved toughness and desirable dielectric properties could have a potential application in the insulation of electronic packaging system. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2008
Co-reporter:Wenying Zhou;Caifeng Wang;Qunli An;Shuhua Qi
Polymer Engineering & Science 2008 Volume 48( Issue 7) pp:1381-1388
Publication Date(Web):
DOI:10.1002/pen.21113
Abstract
The properties of silicone rubber filled with three kinds of binary mixtures of alumina particles with different size distribution (i.e., 30 μm + 0.5 μm, 10 μm + 0.5 μm, and 5 μm + 0.5 μm) were investigated as a function of relative volume fraction of the 0.5 μm particles in the hybrid alumina (Vs) at a fixed total filler content of 55 vol%. The results indicate that each binary mixture of alumina-filled silicone rubber exhibited improved thermal conductivity and tensile strength, and decreased dielectric constant, compared to a single particle size filler-reinforced one, and the maximum improvements were obtained at the Vs ranging from 0.2 to 0.35; the coefficient of thermal expansion (CTE) of filled silicone rubber obviously reduced with increase in the Vs, whereas the elongation at break slightly decreased. At Vs = 0, the larger particles-filled silicone rubber showed higher thermal conductivity, CTE, dielectric constant, and elongation at break, and lower tensile strength compared with the those of the smaller particles-filled one. POLYM. ENG. SCI., 2008. © 2008 Society of Plastics Engineers
Co-reporter:Min Hu, Demei Yu, Jianbo Wei
Polymer Testing 2007 Volume 26(Issue 3) pp:333-337
Publication Date(Web):May 2007
DOI:10.1016/j.polymertesting.2006.11.003
A DSC method that utilizes a very simple accessory designed for measuring thermal conductivity of polymers is described. The method does not require any use of temperature sensors and any modification to the DSC instrument. Measurements by this method are very rapid, each measurement only takes a few minutes. The method is particularly suitable for small samples, such as cylinders of 6 mm in diameter and 2–8 mm in length. In contrast to the existing DSC methods wherein thermal contact resistance usually leads to great deviation in thermal conductivity measurement of samples, the method described in this work minimizes the effect of thermal contact resistance. Thermal conductivities have been obtained from PMMA, PTFE and HDPE samples using this method and the results showed good agreement with the literature values.
Co-reporter:Weitao Wan;Yunchuan Xie;Xiusheng Guo;Wi Zhou and;Jiping Cao
Journal of Applied Polymer Science 2006 Volume 102(Issue 4) pp:3480-3488
Publication Date(Web):29 AUG 2006
DOI:10.1002/app.24561
Effects of nanoparticle surface treatment on the crystallization behavior and mechanical properties of polypropylene (PP)/CaCO3 nanocomposites were investigated by using differential scanning calorimetry (DSC), polarized optical microscope (POM), X-ray diffraction (XRD), transmission electron microscopy (TEM), and scanning electron microscopy (SEM). The results demonstrated that the interfacial interaction formed between PP and nanoparticles significantly influenced the thermal and mechanical properties of nanocomposites. It was found that CaCO3 nanoparticles modified by a single aluminate coupling agent (CA-1) could improve the onset crystallization temperature more effectively than that modified by a compound surface-treating agent (CA-2) could. However, there is no significant difference in total rate of crystallization for the two PP/CaCO3 nanocomposites (PPC-1 and PPC-2), which contained CA-1 and CA-2, respectively. In contrast, CA-2 modified nanoparticles could cause smaller spherulites and induce much more β-phase crystal in nanocomposites than that of CA-1 modified nanoparticles. This may be explained by a synergistic effect of aluminate coupling agent and stearic acid in CA-2, which also resulted in an improved toughness for PPC-2. © 2006 Wiley Periodicals, Inc. J Appl PolymSci 102: 3480–3488, 2006
Co-reporter:Qiong Tian, Xiaojing Yu, Lifeng Zhang, Demei Yu
Journal of Colloid and Interface Science (1 April 2017) Volume 491() pp:
Publication Date(Web):1 April 2017
DOI:10.1016/j.jcis.2016.12.047
Raspberry-like multihollow polymer microspheres were prepared by seeded swelling polymerization and decorated with silver nanoparticles (AgNPs) in the presence of polyvinylpyrrolidone (PVP) which acted as both reducing and stabilizing agent. Formation mechanism of the raspberry-like multihollow microsphere was discussed on the basis of water absorption of sulfonated groups in the seeded swelling polymerization. Effects of weight ratio of sodium 4-vinylbenzenesulfonate to styrene (NaSS/St) of the seed particles, the concentration of PVP and [Ag(NH3)2]+ ions on the properties of polymer/Ag nanocomposite microspheres were investigated by microscopic observation, nitrogen adsorption/desorption isotherms, UV–vis absorption spectra, X-ray diffraction patterns and thermogravimetric analysis. The results demonstrated that the raspberry-like multihollow microspheres were successfully fabricated by controlling over the NaSS/St of the seed particles in the seeded swelling polymerization by which the fabrication of hollow structure became simple and convenient. The spherical AgNPs were loaded on the polymer microsphere by in-situ chemical reduction due to the stabilization and reduction of PVP and the attraction between sulfonated groups and [Ag(NH3)2]+ ions. The raspberry-like multihollow polymer/Ag microspheres showed good catalytic activity and reusability in the degradation of methylene blue in the presence of NaBH4.
Co-reporter:Xin Xu, Jin Liang, Han Zhou, Dongmei Lv, Fuxin Liang, Zhenglong Yang, Shujiang Ding and Demei Yu
Journal of Materials Chemistry A 2013 - vol. 1(Issue 9) pp:NaN2998-2998
Publication Date(Web):2013/01/17
DOI:10.1039/C3TA01372C
Uniform SnO2 nanotubes with a mesoporous shell were successfully prepared by calcination of SnO2@polymeric nanotubes. The SnO2 nanotubes possess enhanced lithium storage performance compared with SnO2 hollow spheres and SnO2 nanoparticles owing to the unique structure of mesoporous shell, open ends and hollow interior.
Co-reporter:Xin Xu, Guorui Yang, Jin Liang, Shujiang Ding, Chengli Tang, Honghui Yang, Wei Yan, Guidong Yang and Demei Yu
Journal of Materials Chemistry A 2014 - vol. 2(Issue 1) pp:NaN122-122
Publication Date(Web):2013/10/15
DOI:10.1039/C3TA12863F
TiO2@SnO2 nanosheets@nanotubes heterostructures were successfully prepared by a facile two-step method: prefabricated SnO2@PNT coaxial nanocables based on the in situ growth of SnO2 in the sulfonated gel matrix of polymeric nanotubes, and then the assembly of TiO2 nanoclusters that consist of ultrathin nanosheets through a solvothermal process. These heterostructures were characterized for the morphological, structural and optical properties by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), UV-visible (UV-vis) and diffuse reflectance spectroscopy (DRS). The photocatalytic investigations showed that the TiO2@SnO2 heterostructures possessed enhanced photocatalytic efficiency in the photodegradation of Rhodamine B (RhB) and photocatalytic H2 evolution from water splitting under ultraviolet (UV) light irradiation, compared with the pristine TiO2 nanosheets, SnO2 nanotubes, the mechanically mixed two samples and P25. The enhanced photocatalytic performance can be ascribed to the beneficial microstructure and synergistic effects of coupled TiO2@SnO2 nanosheets@nanotubes heterostructures.
Co-reporter:Xin Xu, Bitao Dong, Shujiang Ding, Chunhui Xiao and Demei Yu
Journal of Materials Chemistry A 2014 - vol. 2(Issue 32) pp:NaN13074-13074
Publication Date(Web):2014/06/17
DOI:10.1039/C4TA02003K
In this paper, we report a facile approach to the synthesis of one-dimension (1D) hierarchical NiCoO2 nanosheets (NSs)@amorphous CNT composites based on the templates and carbon source of polymeric nanotubes (PNTs). Importantly, these sulfonated PNTs can also be used to prepare many other functional 1D metal oxides@amorphous CNT nanostructures, such as TiO2, SnO2, CoO and NiO, etc. Due to the outstanding nanostructures and the synergistic effects of the NiCoO2 NSs and amorphous CNTs, an ultrahigh discharge capacity of 1309 mA h g−1 is delivered by the NiCoO2@CNT composites, even after 300 cycles at a current density of 400 mA g−1. The favorable improvements of the NiCoO2 based lithium-ion batteries (LIBs) reported in this work illustrate that the 1D amorphous carbon matrix offers significant benefits for high-capacity metal oxide anode nanomaterials.
![2,3-DIPHENYLIMIDAZO[1,2-A]PYRIDINE](http://img.cochemist.com/ccimg/85200/85102-26-7.png)
![2,3-DIPHENYLIMIDAZO[1,2-A]PYRIDINE](http://img.cochemist.com/ccimg/85200/85102-26-7_b.png)
![2-(p-Tolyl)imidazo[1,2-a]pyridine](http://img.cochemist.com/ccimg/66000/65964-60-5.png)
![2-(p-Tolyl)imidazo[1,2-a]pyridine](http://img.cochemist.com/ccimg/66000/65964-60-5_b.png)
![3-METHYL-2-PHENYLIMIDAZO[1,2-A]PYRIDINE](http://img.cochemist.com/ccimg/34700/34658-68-9.png)
![3-METHYL-2-PHENYLIMIDAZO[1,2-A]PYRIDINE](http://img.cochemist.com/ccimg/34700/34658-68-9_b.png)
![2-(4-Fluorophenyl)imidazo[1,2-a]pyridine](http://img.cochemist.com/ccimg/400/347-12-6.png)
![2-(4-Fluorophenyl)imidazo[1,2-a]pyridine](http://img.cochemist.com/ccimg/400/347-12-6_b.png)
