Co-reporter:Gehong Su;Xifei Liu;Yanan Ma
Polymer Chemistry (2010-Present) 2017 vol. 8(Issue 5) pp:865-878
Publication Date(Web):2017/01/31
DOI:10.1039/C6PY01935H
In this study, the micro-dynamics mechanism of the volume phase transition behavior of the poly(N-isopropylacrylamide-co-2-hydroxyethyl methacrylate) (PNIPAM-co-HEMA) hydrogel was investigated by temperature-dependent FTIR spectroscopy in combination with the perturbation correlation moving window (PCMW2D) technique and generalized two-dimensional correlation analysis. In conventional 1D FTIR spectra analysis, Boltzmann fitting curves showed that the volume phase transition temperature and the phase transition degree of the PNIPAM-co-HEMA hydrogel were lower than those of the pure PNIPAM hydrogel. They also showed that the PHEMA segments exhibit a similar “phase transition” behavior to the PNIPAM segments, which can be ascribed to the driving effect of the phase transition of PNIPAM segments. Furthermore, we found that the rate at which water molecules were expelled out of the gel structure during phase transition changed in an anti-S shape. PCMW2D spectra revealed that the phase transition can be divided into two processes (named I and II) upon heating, and further determined the temperature regions of processes I and II to be 21.8–31.4 °C and 31.4–36.5 °C, respectively. Finally, generalized 2D correlation analysis found that both processes I and II can be further divided into nine steps. From the deduced nine steps of process I, the significant role of PHEMA in the phase transition of PNIPAM segments was revealed. As for the deduced nine steps of process II, the driving effect of the phase transition of PNIPAM segments for PHEMA segments was confirmed.
Co-reporter:Gehong Su;Xifei Liu;Yulin Zhang
Physical Chemistry Chemical Physics 2017 vol. 19(Issue 40) pp:27221-27232
Publication Date(Web):2017/10/18
DOI:10.1039/C7CP04571A
In this study, temperature-dependent FTIR spectroscopy in combination with the perturbation–correlation moving-window (PCMW2D) technique and generalized two-dimensional (2D) correlation analysis was applied to investigate the phase transition mechanism of poly(N-vinylcaprolactam) (PVCL) hydrogel upon heating. In the conventional 1D FTIR spectra, the gradual dehydration of C–H groups, as well as the gradual dissociation of hydrogen bonds between CO groups and water molecules, was observed during phase transition. Moreover, we found that the rate at which water molecules were expelled out of the gel network during phase transition was changed to a sigmoid mode, rather than increasing linearly with increasing temperature. PCMW2D FTIR spectra revealed that the phase transition of PVCL hydrogel can be divided into two steps (named as I and II) upon heating, and we further determined the temperature regions of steps I and II to be 29.0–35.7 °C and 35.7–47.5 °C, respectively. Step I is the formation of hydrophobic domains in the gel, and step II is the chain collapse of the gel. Finally, with the help of generalized 2D correlation analysis, it was confirmed that the transformation of hydrogen bonds was the driving force of the hydrophobic domain formation process, while the hydrophobic interaction of C–H groups was the driving force for the chain collapse process. Combined with the obtained sequential orders of step I and step II, an integrated two-step phase transition mechanism of PVCL hydrogel upon heating was proposed.
Co-reporter:Liang Wen, Tao Zhou, Jihai Zhang, and Aiming Zhang
ACS Applied Materials & Interfaces 2016 Volume 8(Issue 41) pp:28077
Publication Date(Web):September 26, 2016
DOI:10.1021/acsami.6b09504
Graphene has been successfully applied to the field of polymer laser patterning. As an efficient 1064 nm near-infrared (NIR) pulsed laser absorber, only 0.005 wt % (50 ppm) of graphene prepared by mechanical exfoliation endowed polymer materials with very good NIR pulsed laser patterning. Optical microscopy observed that the generated black patterns came from the local discoloration of the polymer surface subjected to the laser irradiation, and the depth of the discolored layer was determined to be within 221–348 μm. The X-ray photoelectron spectroscopy confirmed that the polymer surface discoloration was contributed by the local carbonization of polymers caused by graphene due to its high photothermal conversion capacity. Raman depth imaging successfully detected that the generated carbon in the discolored layer was composed of amorphous carbon and complex sp/sp2-carbon compounds containing C≡C or conjugated C═C/C≡C structures. This study also provides a simple guideline to fabricate laser-patterning polymer materials based on graphene. We believe that graphene has broad application prospects in the field of polymer laser patterning. Importantly, this work opens up a valuable, feasible direction for the practical application of this new carbon material.Keywords: carbonization; graphene; laser patterning; near-infrared pulsed laser; polymer
Co-reporter:Jihai Zhang, Tao Zhou, Liang Wen, Jing Zhao, and Aiming Zhang
ACS Applied Materials & Interfaces 2016 Volume 8(Issue 3) pp:1977
Publication Date(Web):December 30, 2015
DOI:10.1021/acsami.5b10243
This study developed a simple way to achieve legible and local controllable patterning for polymers based on a near-infrared (NIR) pulsed laser. The polycarbonate-coated nano antimony-doped tin oxide (nano ATO) was designed as a core–shell structure that was tailored to be responsive to a 1064 nm NIR laser. The globular morphology of polycarbonate-coated nano ATO with a diameter of around 2–3 μm was observed by scanning electron microscopy and transmission electron microscopy. This core–shell structure combined the excellent photothermal conversion efficiency of nano ATO and the high char (carbon) residue of polycarbonate. The X-ray photoelectron spectroscopy results of a polymer-patterning plate after laser irradiation demonstrated that, through local controlled photochromism, the well-defined legible patterns can be fabricated on the polymer surfaces contribute to the synergistic effect consisting of polycarbonate carbonization and nano ATO photothermal conversion. Furthermore, polymers doped with a minimal content of polycarbonate-coated nano ATO can achieve a remarkable patterning effect. This novel laser-patterning approach will have wide promising applications in the field of polymer NIR pulsed-laser patterning.Keywords: carbonization; laser patterning; nano antimony-doped tin oxide; near-infrared pulse laser; polymer
Co-reporter:Gehong Su, Tao Zhou, Yanyan Zhang, Xifei Liu and Aiming Zhang
Soft Matter 2016 vol. 12(Issue 4) pp:1145-1157
Publication Date(Web):06 Nov 2015
DOI:10.1039/C5SM02542G
A good understanding of the microdynamics of the water absorption of poly(2-hydroxyethyl methacrylate) (PHEMA)-based contact lens is significant for scientific investigation and commercial applications. In this study, time-dependent ATR-FTIR spectroscopy combined with the perturbation correlation moving-window two-dimensional (PCMW2D) technique and 2D correlation analysis was used to study the microdynamics mechanism. PCMW2D revealed that D2O took 3.4 min to penetrate into the contact lens. PCMW2D also found the PHEMA-based contact lens underwent two processes (I and II) during D2O absorption, and the time regions of processes I and II are 3.4–12.4 min and 12.4–57.0 min. According to 2D correlation analysis, it was proved that process I has 5 steps, and process II has 3 steps. For process I, the first step is D2O hydrogen-bonding with “free” CO in the side chains. The second step is the hydrogen bond generation of the O–H⋯O–D structure between D2O and “free” O–H groups in the side chain ends. The third step is the hydrogen bond generation of D2O and the “free” CO groups close to the crosslinking points in the contact lens. The fourth and the fifth steps are the hydration of –CH3 and –CH2– groups by D2O, respectively. For process II, the first step is the same as that of process I. The second step is the hydrogen bonds breaking of bonded O–H groups and the deuterium exchange between D2O and O–H groups in the side chain ends. The third step is also related to the deuterium exchange, which is the hydrogen bonds regeneration between the dissociated CO groups and the new O–D.
Co-reporter:Jing Zhao, Jihai Zhang, Tao Zhou, Xifei Liu, Qiang Yuan and Aiming Zhang
RSC Advances 2016 vol. 6(Issue 6) pp:4397-4409
Publication Date(Web):22 Dec 2015
DOI:10.1039/C5RA24320C
Polyacrylonitrile (PAN) copolymer fiber pre-oxidation has important influence on the final properties of carbon fibers. Understanding and tracking the reaction pathways of this pre-oxidation has great significance in guaranteeing the quality of the resulting carbon fibers. In this study, in situ FTIR spectroscopy in combination with scaling moving-window two-dimensional correlation spectroscopy (scaling-MW2D) and 2D correlation analysis was used to study the reaction pathways. In addition, DSC and 13C solid-state NMR were used to assist in the determination and verification of chemical structures. Scaling-MW2D revealed that pre-oxidation consists of an initial process (A, 69–223 °C) and a main process (B, 223–309 °C). From the sequential order of 2D correlation analysis, more detailed pathways were obtained. The induced reaction of comonomer units took place in process A (69–223 °C). In process B (223–309 °C), the initial cyclic structures were first generated from the induced structure formed in process A. Then, these initial cyclic structures underwent a series of oxidations and subsequent isomerization. Subsequently, a large number of AN units were immediately involved in the main cyclization reaction, and some β-amino nitriles were produced. One new understanding obtained is that the initial cyclic structures after oxidation and isomerization are the real induced “nucleus” of the main cyclization reaction, and therefore oxygen in the air plays a key role in the main cyclization of PAN. The final step is the dehydrogenation reaction on the polycyclic structures at a high temperature.
Co-reporter:Jiaojiao Ma, Ying Li, Xiande Yin, Yu Xu, Jia Yue, Jianjun Bao and Tao Zhou
RSC Advances 2016 vol. 6(Issue 55) pp:49448-49458
Publication Date(Web):12 May 2016
DOI:10.1039/C6RA08760D
This paper described a novel and bottom-up in situ polymerization method for preparing poly(vinyl alcohol) (PVA)/graphene oxide (GO) nanocomposites. The approach is conducted by mixing vinyl acetate, methanol, initiator and GO with the aid of high power ultrasound, followed by free radical polymerization and alcoholysis reaction, resulting in the in situ formation of PVA matrix and molecular level dispersion of GO. X-ray diffraction, transmission electron microscopy and scanning electron microscopy revealed that GO nanosheets were completely intercalated, uniformly dispersed and highly oriented along the surface of the nanocomposite films. Centrifugation experiments, Fourier-transform infrared spectroscopy and differential scanning calorimetry evidenced the existence of strong hydrogen bond interactions between the GO nanosheets and PVA matrix. Furthermore, the mechanical properties and water vapor barrier properties of PVA/GO nanocomposites had been strikingly enhanced by adding a small amount of GO (with GO loading as low as 0.01–0.08 wt%). Compared with the neat polymer, the tensile strength increased from 42.3 to 50.8 MPa and Young's modulus increases markedly from 1477 to 2123 MPa at the GO incorporation of only 0.04 wt%. Moreover, it gave rise to about 78% decline in the coefficient of moisture permeability.
Co-reporter:Liang Wen, Jihai Zhang, Tao Zhou, Aiming Zhang
Vibrational Spectroscopy 2016 Volume 86() pp:160-172
Publication Date(Web):September 2016
DOI:10.1016/j.vibspec.2016.07.001
•Micro-phase separation of polyamide elastomer was studied by scaling-MW2D.•Enthalpy of hydrogen bonds was calculated from FTIR via Van’t Hoff analysis.•Both enthalpies and molecular movements show hydrogen bonding plays a key role.The role of hydrogen bonds to the micro-phase separation process of poly(polyamide 12-block-polytetrahydrofuran) alternating block copolymer upon cooling (170–15 °C) was investigated by in situ FTIR spectra combined with scaling moving-window two-dimensional correlation spectroscopy (scaling-MW2D) and the generalized 2D correlation analysis. The micro-phase separation process of polyamide elastomer was found to be composed of two processes via the combination of scaling-MW2D and differential scanning calorimetry (DSC). The first process (process A, 138–80 °C) is the initial process of the micro-phase separation of the polyamide elastomer, and the second process (process B, 80–35 °C) is the completion process of the micro-phase separation. The method of calculating the generation enthalpy of hydrogen bonds from in situ FTIR was also successfully established via Van’t Hoff analysis, and the above two processes were further confirmed through the enthalpy of hydrogen bonding. The generalized 2D correlation analysis was performed for these two processes. The results of 2D correlation analysis revealed that the impetus for the process A was the generation of the disordered hydrogen bonds between the CO and N–H groups in the PA12 blocks, the PA12 crystallization induced by the formation of the ordered hydrogen bonds is the key step of the process B.
Co-reporter:Jihai Zhang, Tao Zhou, Liang Wen, and Aiming Zhang
ACS Applied Materials & Interfaces 2016 Volume 8(Issue 49) pp:
Publication Date(Web):November 17, 2016
DOI:10.1021/acsami.6b11305
Nowadays, with the rapid development of portable electronics, wearable electronics, LEDs, microelectronics, and bioelectronics, the fabrication of metallic circuits onto polymer substrates with strong adhesion property is an ever-increasing challenge. In this study, the high-resolution and well-defined metallic circuits were successfully prepared on the polymer surface via laser direct structuring (LDS) based on copper hydroxyl phosphate [Cu2(OH)PO4], and the key mechanism of the selective metallization was systematically investigated. XPS confirmed that Cu0 (elemental copper) was formed through photochemical reduction reaction of Cu2(OH)PO4, after 1064 nm NIR pulsed laser irradiation. During the electroless plating, because it is the important active catalytic center, this newly formed Cu0 was the key factor to achieve the successful selective metallization. SEM revealed that after the electroless plating, the copper layer actually physically anchored into the polymer substrate, giving an excellent mechanical adhesion property of the obtained metallic patterns. In addition, the micro-Raman surface imaging approved the generation of the amorphous carbon on the polymer composites’ surface after NIR laser irradiation, and the chemical reaction region caused by the pulsed laser spot was found at approximately 40 μm. This environmentally friendly and effective strategy for fabricating circuit patterns on the polymer surface has a possible application in the printed circuit plate (PCB) industry.Keywords: copper hydroxyl phosphate; laser direct structuring; metallization; near-infrared pulsed laser; polymer;
Co-reporter:Jihai Zhang, Tao Zhou, Liping Xia, Canyao Yuan, Weidong Zhang and Aiming Zhang
Journal of Materials Chemistry A 2015 vol. 3(Issue 5) pp:2387-2398
Publication Date(Web):03 Dec 2014
DOI:10.1039/C4TA05462H
In this study, a carbon-based polypropylene thermoplastic elastomer (PP-elastomer) composite for current collectors of an all-vanadium redox flow battery (VRB) was successfully prepared. The volume resistivity of the PP-elastomer composite was 0.47 Ω cm. Its tensile strength and elongation at break were 6.6 MPa and 250%, respectively. In addition, the good flow property in processing means this composite has potential for the mass industrial production of current collectors. The single cell and the cell stack of a VRB equipped with the composite current collectors were assembled for battery tests, including cyclic voltammetry, long-term performance, long-term stability, and oxidation corrosion. To evaluate the stability and the performance of the cell stack under a long-term operating condition, tests with more than 2300 charge–discharge cycles were carried out. The coulombic efficiency (CE) and voltage efficiency (VE) of the cell stack were maintained at around 93% and 80% during 2300 charge–discharge cycles, and energy efficiency (EE) held at around 75%. The results proved that a VRB equipped with composite current collectors has good stability and performance. Furthermore, long-term corrosion tests indicated that the PP-elastomer composite could endure the strong corrosion of pentavalent vanadium and concentrated sulfuric acid. The composite materials prepared in this study are more suitable than other materials for producing the current collectors. The corrosion resistance of composite materials is much better than that of the graphite, and the mechanism is also discussed.
Co-reporter:Ying Li, Yu Xu, Tao Zhou, Aiming Zhang and Jianjun Bao
RSC Advances 2015 vol. 5(Issue 41) pp:32469-32478
Publication Date(Web):23 Mar 2015
DOI:10.1039/C5RA01984B
In this study, a method to construct perfect three-dimensional (3D) polymer/graphene oxide (GO) core–shell microspheres was proposed via electrostatic self-assembly. 2D GO nanosheets were successfully wrapped onto polymer microspheres to form a perfect 3D core–shell structure with uniform shell thickness under the action of an electrostatic attraction force. The GO nanosheets, with a thickness of 1.5–2 nm and an area over 2 × 1 μm2, were firstly prepared from graphite, and then cationic polystyrene (PS) microspheres with 0.246% and 0.715% surface concentrations of –N(CH3)3+ were successfully synthesized. After that, PS/GO core–shell microspheres were constructed from the GO nanosheets and the cationic PS microspheres. It was found that different cationic PS microspheres led to different assembly speeds. SEM and TEM images of rippled silk waves on the surface of the PS/GO core–shell microspheres not only indicated the perfect polymer/GO core–shell structure, but also demonstrated the strong binding between the two materials. It was also revealed that the thicknesses of the shells of the PS/GO core–shell microspheres were under good control, and the thicknesses of shells from different cationic PS microspheres were 9–13 nm and 80–100 nm. The method proposed here has proved to be a valuable tool for the assembly of 3D microstructures from polymers and graphene oxide (or graphene).
Co-reporter:Tao Zhou, Ting Zhou and Aiming Zhang
RSC Advances 2015 vol. 5(Issue 19) pp:14832-14842
Publication Date(Web):26 Jan 2015
DOI:10.1039/C4RA16373G
This study developed a new analytical method called projection moving-window 2D correlation FTIR spectroscopy (Proj-MW2D) to separate the molecular motion of groups generated from different components or phases for multiphase and multicomponent polymers. The specific implementation steps for Proj-MW2D were enumerated after the theoretical derivation and algorithm research. Two types of two-component blends, poly(L-lactide)/poly(butylene succinate) and monodisperse polystyrene/monodisperse poly(ethylene-co-1-butene), were employed to validate the concept of separating the molecular motion of groups. Results showed that the Proj-MW2D FTIR correlation technique successfully separated the molecular motion of the specific functional groups. Although MW2D and PCMW2D have the capacity to determine the multiple transitions of polymers, they cannot identify the origin of correlation intensity peaks without the help of other characterization methods. Proj-MW2D allows researchers to study the mechanism of the complex transition process for multiphase and multicomponent polymer systems. This method can be easily extended to three- or four-component polymers and to other spectra (e.g., Raman, X-ray, and UV).
Co-reporter:Xifei Liu, Tao Zhou, Yongcheng Liu, Aiming Zhang, Canyao Yuan and Weidong Zhang
RSC Advances 2015 vol. 5(Issue 14) pp:10231-10242
Publication Date(Web):07 Jan 2015
DOI:10.1039/C4RA13502D
cis-Polybutadiene rubber (cis-BR) is one of the typical unsaturated rubbers in mass production and is widely used. However, the detailed mechanism of its cross-linking with peroxides is still unclear so far. In this study, in situ FTIR spectra combined with the powerful PCMD2D and 2D correlation spectroscopy was used to track the detailed cross-linking process. The temperature region of cis-BR cross-linking determined by PCMW2D was within 165–195 °C. The temperature with a maximum cross-linking rate was determined at 183 °C via PCMW2D, which is identical with DSC. The generation of –˙CH– macromolecular free radicals through losing α hydrogens was observed when below 165 °C. An abnormal increase of double bonds with trans-1,4-structure during the cross-linking (165–195 °C) was observed. An obvious enhancement of –CH2– groups was also found, which indicated that a large number of the double bonds with cis-1,4- and 1,2-structure involved in cross-linking is transformed into –CH2– groups. A 5-step process for the whole cross-linking was inferred from the sequential order of group motions. The first step is DCP decomposition and free radical release. The second step is the generation of trans-1,4-structure due to the internal rotation of the cis-1,4-structure induced by free radicals at α position. The third step is the free radical addition of double bonds with a 1,2-structure, and the fourth is the free radical addition of double bonds with a cis-1,4-structure. The final step is the cross-linking via double coupling of two macromolecular free radicals. In the last step, the free radicals from the cis-1,4-structure also can be probably terminated by a chain transfer.
Co-reporter:Gehong Su, Tao Zhou, Xifei Liu, Jihai Zhang, Jianjun Bao and Aiming Zhang
RSC Advances 2015 vol. 5(Issue 103) pp:84729-84745
Publication Date(Web):22 Sep 2015
DOI:10.1039/C5RA13486B
In this paper, quantitative spectroscopic evidence for the important role of hydrogen bonds during the cooling crystallization of poly(ethylene-co-vinyl alcohol) (EVOH) was successfully obtained. Furthermore, the detailed molecular movements during the crystallization of EVOH were revealed via two-dimensional correlation infrared spectroscopy. Two cooling crystallization processes were detected at 159 °C and around 101–105 °C via the combination of DSC and the newly proposed scaling-MW2D correlation FTIR spectroscopy. These two crystallization processes were defined as the primary crystallization (region I) and the secondary perfection process (region II) of EVOH. The methods for calculating the enthalpies of the pair-bonded hydrogen bonding (ΔHh), vinyl alcohol (VA) repeating unit crystallization (ΔHC-VA), VA repeating unit diffusion into the crystal lattice (ΔHl-VA), and ethylene (ET) repeating unit crystallization (ΔHC-ET) were established via van ’t Hoff plots. For regions I and II, the contributions of the pair-bonded hydrogen bonding of the VA repeating units to the entire EVOH crystallization were 42.8% (ΔHh = −90.4 ± 5.2 kJ mol−1) and 64.6% (ΔHh = −75.8 ± 3.1 kJ mol−1), respectively. However, the contributions of the ET crystallization to the EVOH crystallization were 19.4% (ΔHC-ET = −41.0 ± 2.0 kJ mol−1) and 32.7% (ΔHC-ET = −38.3 ± 0.8 kJ mol−1), which were only half of the contributions of the pair-bonded hydrogen bonding. 2D correlation analysis was used to investigate the sequential order of the groups’ movement in the crystallization. It was found that region I had 3 steps. The first step is the formation of the hydrogen bonds in the VA repeating unit, and the second step is the diffusion of the VA repeating unit into the crystal lattice, resulting in the primary crystallization. The third step is the ET repeating unit crystallization accompanied by the movement of the VA repeating unit without hydrogen bonding in the amorphous region. Region II had 4 steps. The first step is also the generation of the hydrogen bonds in the VA repeating unit. The second step is a local rearrangement of the lattice in the imperfect crystalline of the VA repeating unit, called the secondary perfection process. The third step is the movement of the VA repeating unit without hydrogen bonding in the amorphous region. The fourth step is the weak crystallization of the ET repeating unit at a low temperature.
Co-reporter:Qiang Yuan, Tao Zhou, Lin Li, Jihai Zhang, Xifei Liu, Xiaolin Ke and Aiming Zhang
RSC Advances 2015 vol. 5(Issue 39) pp:31153-31165
Publication Date(Web):25 Mar 2015
DOI:10.1039/C5RA03984C
Hydrogen bond breaking of TPU based on 4,4′-methylenediphenyl diisocyanate (MDI)/1,4-butanediol (BDO) upon heating was studied and elucidated from molecular movements and enthalpy. Two temperature regions of hydrogen bond breaking, region I (80–133 °C) and region II (133–169 °C), were determined via the combination of PCMW2D correlation with FTIR and DSC. The method of calculating the enthalpy of the hydrogen bond breaking was established via Van't Hoff plots. We also proposed a method of calculating the relative content of different hydrogen bonds. In region I, ΔHh = 58.8 ± 0.5 kJ mol−1 for N–H and CO, and ΔHh = 37.2 ± 0.4 kJ mol−1 for N–H and C–O–C groups. The content of hydrogen bonds generated by N–H and CO is 88.4%, and that of N–H and C–O–C is 11.6%. In region II, ΔHh = 65.0 ± 1.1 kJ mol−1 for N–H and CO, and ΔHh = 73.0 ± 3.9 kJ mol−1 for N–H and C–O–C groups. The contents of these two hydrogen bonds are 71.2% and 28.8%, respectively. The surprisingly high value of ΔHh = 73.0 ± 3.9 kJ mol−1 for N–H and C–O–C in region II is actually due to the stabilizing effect of the repulsion energy on hydrogen bonds at the interface. 2D correlation analysis was used to investigate the sequential order of the groups' movement involved in hydrogen bond breaking. In region I, the breaking of a small amount of hydrogen bonds between N–H and C–O–C at the interface first occurs, and then the breaking of irregular hydrogen bonds between N–H and CO in the TPU hard blocks dominates, resulting in the melting of the imperfect crystallinity in the hard blocks. In region II, the breaking of regular hydrogen bonds between N–H and CO in the perfect crystalline of the hard blocks first occurs, and is then followed by hydrogen bond breaking of N–H and C–O–C enhanced by the repulsion energy at the interface, leading to the order–disorder transition (ODT) of TPU.
Co-reporter:Jihai Zhang;Jing Zhao;Canyao Yuan;Liping Xia;Ningfeng Sun;Weidong Zhang;Aimin Zhang
Journal of Applied Polymer Science 2015 Volume 132( Issue 11) pp:
Publication Date(Web):
DOI:10.1002/app.41644
ABSTRACT
In this article, a conductive foam based on a novel styrene-based thermoplastic elastomer called poly(styrene-b-butadiene-co-styrene-b-styrene) tri-block copolymer S(BS)S was prepared and introduced. S(BS)S was particularly designed for chemical foaming with uniform fine cells, which overcame the shortcomings of traditional poly(styrene-b-butadiene-b-styrene) tri-block copolymer (SBS). The preparation of conductive foams filled by the carbon black was studied. After the detail investigation of cross-linking and foaming behaviors using moving die rheometer, the optimal foaming temperature was determined at 180°C with a complex accelerator for foaming agent. Scanning electron microscopy (SEM) images shown that the cell bubbles of conductive foam were around 30–50 µm. The conductivity of foams was tested using a megger and a semiconductor performance tester. SEM images also indicated that the conductivity of foams was mainly affected by the distribution of carbon black in the cell walls. The formation of the network of the carbon black aggregates had a contribution to perfect conductive paths. It also found that the conductivity of foams declined obviously with the foaming agent content increasing. The more foaming agent led to a sharp increasing of the number of cells (from 2.93 × 106 to 6.20 × 107 cells/cm3) and a rapid thinning of the cell walls (from 45.3 to 1.4 µm), resulting in an effective conductive path of the carbon black no forming. The conductive soft foams with the density of 0.48–0.09 g/cm3 and the volume resistivity of 3.1 × 103−2.5 × 105 Ω cm can be easily prepared in this study. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41644.
Co-reporter:Lin Li;Jianzhong Liu;Qianping Ran;Guangdou Ye;Jihai Zhang;Pengqing Liu;Aiming Zhang;Zhiqian Yang;Degen Xu;Jiaping Liu
Polymers for Advanced Technologies 2015 Volume 26( Issue 1) pp:77-84
Publication Date(Web):
DOI:10.1002/pat.3422
Polyoxymethylene (POM) fiber was produced by melt spinning with a high take-up speed, which imposed a strong flow field. An unexpected formation of a shish-kebab morphology with multiple shish of POM fibers was reported for the first time. This morphology is a large-scale shish kebab with a diameter of 10.5 µm. Further orientation of the POM fiber was obtained by hot stretching twice at 160°C. Two crystalline morphology evolution processes were also observed: (i) the process from the large-scale shish-kebab to the deformed small shish-kebab and (ii) the process from the deformed small shish-kebab to the perfect whiskers. Compared with the melt spinning fiber, fiber tensile strength with first and second hot stretching increased by 976% and 1705%, respectively. The crystalline melting behavior of fibers significantly changes after the first and second hot stretching. The flow field induces a large number of extended chain crystals. Copyright © 2014 John Wiley & Sons, Ltd.
Co-reporter:Jing Zhao, Tao Zhou, Jihai Zhang, Hongmei Chen, Canyao Yuan, Weidong Zhang, and Aiming Zhang
Industrial & Engineering Chemistry Research 2014 Volume 53(Issue 49) pp:19257-19264
Publication Date(Web):November 23, 2014
DOI:10.1021/ie5040732
In this study, a novel waterborne polyurethane-fluorinated acrylic (WFPU) hybrid emulsion was synthesized and introduced. The cross-linker aziridine was used to enhance the film-forming capacity and mechanical property of WFPU. FTIR and XPS results confirmed that WFPU latex was successfully prepared. WFPU has an excellent hydrophobicity, resulting in an obvious increasing of water contact angle from 58.5° to 92.5°. AFM measurements observed that a continuous polymer film was formed after adding the cross-linker, indicating an excellent film-forming capacity of the cross-linked WFPU. The influence of the amount of the cross-linker on the hydrophobicity and mechanical properties was also studied. Cotton coating experiments visually approved that the cotton hydrophobicity is effectively enhanced by WFPU and the cross-linked WFPU. These results indicated that the cross-linked WFPU containing 30 wt % of fluorinated acrylate and 2.93 wt % of cross-linker has a potential as a coating material for water repellent applications due to providing fantastic hydrophobicity, excellent film-forming capacity, and outstanding mechanical properties.
Co-reporter:Chong Cheng, Zhengyang Liu, Xiaoxiao Li, Baihai Su, Tao Zhou and Changsheng Zhao
RSC Advances 2014 vol. 4(Issue 80) pp:42346-42357
Publication Date(Web):29 Aug 2014
DOI:10.1039/C4RA07114J
Recent studies showed that polymeric hydrogels presented promising applications in adsorption to various water contaminants. However, the usages of these synthetic hydrogels are hindered by several inherent shortages, e.g. limited inner porosity, low adsorption capacity and long equilibrium time. In this study, synthetic GO interpenetrated poly(acrylic acid) (PAA) hydrogels as 3D highly-efficient adsorbents were prepared and systematically studied for the first time. The mediating ability of GO on the inner structure and adsorption capacities is examined using two types of PAA hydrogels (PAA1 and PAA2 with different inner structures, prepared by in situ cross-linked polymerization of monomer AA). The results indicated that the prepared PAA2/GO hydrogels exhibited a well-defined and interconnected 3D porous network, which allowed the adsorbate molecules to diffuse easily into the absorbent. The adsorption experiments indicated that the obtained interconnected polymeric composite hydrogels could efficiently remove cationic dyes and heavy metal ions from wastewater; the highest adsorption capacity of the prepared PAA2/GO composite hydrogels could reach as high as 1600 mg g−1, which is highly promising in the treatment of environmental toxins. Moreover, the initial concentration, pH value, desorption ratio, dynamic kinetics and isotherms of the methylene blue (MB) adsorption processes of the prepared PAA2/GO composite hydrogels were also studied in detail. The experimental data of MB adsorption fitted the pseudo-second-order kinetic model and the Langmuir isotherm very well, and the adsorption process was controlled by the intraparticle diffusion. Moreover, due to its facile preparation and low-cost, the GO interpenetrated PAA composite hydrogels may function as promising adsorbents for wastewater treatment, and this method might also be extended to improve the adsorption capacity of other polymeric hydrogels.
Co-reporter:Tao Zhou, Leilei Peng, Yongcheng Liu, Aiming Zhang, Yong Huang
Journal of Molecular Structure 2014 Volume 1059() pp:8-14
Publication Date(Web):5 February 2014
DOI:10.1016/j.molstruc.2013.11.031
•Boltzmann sigmoid function was incorporated into the model-based 2D correlation IR.•Model-based 2D IR was used to study the mechanism of Tg and Tll of monodisperse aPS.•Flip motions of the phenyl rings are earlier than main chains creep of aPS during Tg.•Tll is a consequence of the melts motions and the slippage of chain entanglements.In this paper, a new S-shaped function (model) called Boltzmann sigmoid was incorporated into the model-based 2D correlation infrared spectroscopy. Boltzmann sigmoid is a typical transition function, and it was found from the curve fitting of the IR spectral intensity variations of monodisperse aPS at heating. The glass transition and the liquid–liquid transition of aPS were determined by MW2D IR spectrum. The model-based 2D correlation IR spectroscopy incorporating Boltzmann sigmoid was successfully employed to investigate the mechanism of these two transitions. We found that the flip motion of the side benzene rings is earlier than the creep of the main chains of monodisperse aPS during the glass transition. Moreover, the difference of the sequential order is precisely defined as ΘE = 4.5°. The movements of the main chains and the side benzene rings are completely simultaneous without a difference during the liquid–liquid transition of aPS, and the difference of the sequential order is ΘE = 0°. It represents the whole movement of macromolecular chains of aPS. The liquid–liquid transition is probably a consequence of the onset of melts motions, and the slippage of chain entanglements. The difference of the effective phase angle in the model-based 2D spectra is proportional to the difference of the transition temperature at the different bands in MW2D spectra.
Co-reporter:Yongcheng Liu;Zhengguang Chen;Lin Li;Yanhui Zhan;Aiming Zhang ;Feiwei Liu
Polymers for Advanced Technologies 2014 Volume 25( Issue 7) pp:760-768
Publication Date(Web):
DOI:10.1002/pat.3307
In this study, the unique crystallization behavior of poly(ethylene oxide) (PEO) in polyoxymethylene (POM)/PEO crystalline/crystalline blends was examined in detail. This study was the first to report the typical fractionated crystallization of PEO in POM/PEO blends when PEO is fewer than 30 wt.%. The delayed crystallization temperature of PEO was confirmed at about 5°C to 14°C by using differential scanning calorimetry and perturbation–correlation moving-window 2D correlation IR spectroscopy. Wide-angle X-ray diffraction indicates that no new crystal structures or co-crystals were generated in POM/PEO. The statistical calculations of scanning electron microscopy photos show that the average diameter of PEO particles is 0.227 µm to 1.235 µm and that the number of small particles is as many as 109 magnitudes per cm3. Theory analysis establishes that the delayed crystallization of PEO is a heterogeneous nucleation process and not a homogeneous nucleation process. A significant toughening effect of PEO to POM was also observed. The impact strength of POM/PEO acquires a maximum of 10.5 kJ/m2 when PEO content is 5%. The impact strength of the blend increases by 78.0% compared with pure POM. To improve the toughening effect, the best particle size is established between 0.352 and 0.718 µm, with a PEO particle spacing of 0.351 µm to 0.323 µm. The number of corresponding particles was 0.887 × 109 per cm3 to 3.240 × 109 per cm3. A PEO toughening model for POM was proposed to provide a new and effective way to solve the problem of POM toughening. Copyright © 2014 John Wiley & Sons, Ltd.
Co-reporter:Tao Zhou;Yongcheng Liu;Leilei Peng;Yanhui Zhan
Analytical and Bioanalytical Chemistry 2014 Volume 406( Issue 17) pp:4157-4172
Publication Date(Web):2014 July
DOI:10.1007/s00216-014-7788-6
In the present study, the theory of the data treatment with scaling techniques for moving-window two-dimensional (scaling-MW2D) correlation analysis was first proposed. This new analytical method of spectroscopy can significantly enhance the resolving capacity of the moving-window two-dimensional (MW2D) correlation infrared spectroscopy in the direction of the perturbation variable. So, it strengthened the ability of MW2D to highlight the weak transitions. The in situ infrared spectra of four common polymers, including polyamide 66 (PA66), polystyrene-block-polybutadiene-block-polystyrene block copolymer (SBS), isotactic polypropylene (iPP), and polyoxymethylene (POM), were employed to illustrate the advantages of scaling-MW2D. In the applications of the present study, the conventional autocorrelation MW2D can only distinguish the melting point of PA66, the maximum crystallization temperature of POM, and the primary oxidation of SBS. However, the autocorrelation scaling-MW2D not only can more easily determine the above transitions, but also can identify PA66 brill transition, the dissociation of adsorbed water in PA66, POM secondary crystallization, the glass transition of hard blocks in SBS, and the generation of the aldehyde and hydroxyl groups during SBS oxidation. Our further study found that the selection of the scaling factor α was very important. The golden point α = 0.618 was the best value, and satisfactory application results can be achieved. The slice scaling-MW2D was also investigated. The scaling-MW2D method of spectroscopy can be used elsewhere. The application of this analytical method should not be limited to the infrared spectra, and it also should not be limited to transitions in polymers. This method can be easily extended and applied to other materials and spectra.
Co-reporter:Hao Gui;Lin Li;Ting Zhou;Feiwei Liu;Yanhui Zhan ;Aimin Zhang
Journal of Applied Polymer Science 2013 Volume 130( Issue 5) pp:3411-3420
Publication Date(Web):
DOI:10.1002/app.39610
ABSTRACT
In this article, the structure, properties, and mechanism of reactive compatibilization of epoxy (EP) to polyphenylene sulfide (PPS)/polyamide elastomer (PAe) were investigated in detail. A PPS/PAe/EP ternary system was successfully prepared via reactive extrusion. Its mechanical and rheological properties were greatly improved compared with those of conventional PPS/PAe binary system. The addition of EP to PPS/PAe blend induced a series of chemical reactions. The chain-extended reaction of PPS was verified by high pressure capillary rheometer. The grafting reaction of PPS with PAe was testified by FTIR. The curing reaction of EP was proposed to explain the decreasing of the mechanical properties in PPS/PAe/EP ternary blend when it contained a high content of EP. Additionally, a toughened model was also proposed in PPS/PAe/EP ternary system. The improvement of toughness was attributed to the activation of matrix molecules in the shear band region. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 3411–3420, 2013
Co-reporter:Zhengguang Chen, Tao Zhou, Jiangtao Hui, Lin Li, Yunyong Li, Aiming Zhang, Tianyu Yuan
Vibrational Spectroscopy 2012 Volume 62() pp:299-309
Publication Date(Web):September 2012
DOI:10.1016/j.vibspec.2012.06.005
A new perturbation-correlation moving-window two-dimensional correlation (PCMW2D) infrared spectroscopy was employed to study the complex crystallization of the polyoxymethylene/poly(ethylene oxide) (POM/PEO) crystalline/crystalline blends for the first time. The online polarizing microscope measurement found POM/PEO forms the crystalline/crystalline blends with a typical island structure. The PCMW2D IR spectra determined three processes of the POM/PEO crystallization. The first is the maximum crystallization temperature of POM (138 °C). The second is the POM recrystallization process (72 °C). The thickening speed of the lamellae (FCC), as well as the crystallization of the macrocyclic POM, is faster than the improvement of POM ECC. The existence of the PEO melts significantly decelerates the improvement speed of ECC in interface. The third is the maximum crystallization temperature of PEO (35 °C). According to the results of the generalized 2D correlation analysis, it can be found the POM ECC plays a leading role during the POM/PEO crystallization.
Co-reporter:Jiang Luo, Tao Zhou, Xiaoliang Fu, Hongwen Liang, Aiming Zhang
European Polymer Journal 2011 Volume 47(Issue 2) pp:230-237
Publication Date(Web):February 2011
DOI:10.1016/j.eurpolymj.2010.11.017
The Brill transition of polyamide 66 was investigated by temperature-dependent infrared spectroscopy combined with moving-window two-dimensional (MW2D) correlation spectroscopy. The temperature range of the Brill transition determined by MW2D correlation spectroscopy was 90–170 °C. We employed generalized 2D correlation spectroscopy to study the sequential order of polyamide 66 chains with linear increment of temperature. The movement of the methylene segments near to NH is earlier than those on the CO sides. At the same time, the methylene which is close to NH varies before the inner methylene. Three kinds of NH groups in polyamide 66 were found. The sequential order of their motions is as follows. The free hydrogen-bonded NH groups change first, and then the disordered hydrogen-bonded NH groups. Finally, the ordered hydrogen-bonded NH groups start to change. We also found that the changes of the ordered hydrogen-bonded NH groups follow with the methylene groups.
Co-reporter:Yunyong Li, Tao Zhou, Zhengguang Chen, Jiangtao Hui, Lin Li, Aiming Zhang
Polymer 2011 Volume 52(Issue 9) pp:2059-2069
Publication Date(Web):19 April 2011
DOI:10.1016/j.polymer.2011.03.007
Non-isothermal crystallization process of polyoxymethylene (POM) from the melts was studied by two-dimensional correlation infrared spectroscopy. A hybrid structure of FCC (1135 cm−1) and ECC (904 cm−1) during the crystallization from the molten state was found. Non-isothermal kinetics of POM crystallization was also investigated using DSC curves. A newly perturbation-correlation moving-window two-dimensional (PCMW2D) technique was used to explore the complex crystallization process. We determined three processes in crystallization. The first is the initial stage of the crystal nucleus growing or the formation of certain local ordered structures in the melts. It can be inferred the formation of the crystal nucleus of FCC is earlier than that of the ECC. The second is the maximum crystallization temperature of POM. The last is the further improvements of crystals (especially in ECC) and the crystallization of the cyclic POM of low molecular weight. However, this process of FCC is slower than ECC. The temperature-dependent IR spectra at reheating were also analyzed using PCMW2D.
Co-reporter:Tao Zhou, Zhiyong Wu, Yunyong Li, Jiang Luo, Zhengguang Chen, Jingkui Xia, Hongwen Liang, Aiming Zhang
Polymer 2010 Volume 51(Issue 18) pp:4249-4258
Publication Date(Web):19 August 2010
DOI:10.1016/j.polymer.2010.06.051
The temperature-dependent transitions of polystyrene-block-poly(ethylene-co-1-butene)-block-polystyrene block copolymer (SEBS) at high temperature were studied using infrared spectroscopy combined with two-dimensional (2D) correlation spectroscopy. The order–order transition (OOT), the lattice disordering transition (LDT), and the order–disorder transition (ODT) of SEBS were explored with a linear temperature increment ranging from 100 to 220 °C. AFM was employed to study the surface morphology of SEBS and to identify the correlation intensity peaks in the MW2D spectra. The OOT was determined around 152 °C. The LDT appears around 170 °C. The ODT was also successfully determined around 202 °C. It is gained that the key driver of the OOT is the movements of –CH2– in the main chains of EB blocks. In the LDT, the movements of groups are simultaneous and the SEBS molecular chains move as a whole. In the ODT, it shows the driver is the movements of –CH2– in the main chains of EB blocks.
Co-reporter:Jihai Zhang, Tao Zhou, Liping Xia, Canyao Yuan, Weidong Zhang and Aiming Zhang
Journal of Materials Chemistry A 2015 - vol. 3(Issue 5) pp:NaN2398-2398
Publication Date(Web):2014/12/03
DOI:10.1039/C4TA05462H
In this study, a carbon-based polypropylene thermoplastic elastomer (PP-elastomer) composite for current collectors of an all-vanadium redox flow battery (VRB) was successfully prepared. The volume resistivity of the PP-elastomer composite was 0.47 Ω cm. Its tensile strength and elongation at break were 6.6 MPa and 250%, respectively. In addition, the good flow property in processing means this composite has potential for the mass industrial production of current collectors. The single cell and the cell stack of a VRB equipped with the composite current collectors were assembled for battery tests, including cyclic voltammetry, long-term performance, long-term stability, and oxidation corrosion. To evaluate the stability and the performance of the cell stack under a long-term operating condition, tests with more than 2300 charge–discharge cycles were carried out. The coulombic efficiency (CE) and voltage efficiency (VE) of the cell stack were maintained at around 93% and 80% during 2300 charge–discharge cycles, and energy efficiency (EE) held at around 75%. The results proved that a VRB equipped with composite current collectors has good stability and performance. Furthermore, long-term corrosion tests indicated that the PP-elastomer composite could endure the strong corrosion of pentavalent vanadium and concentrated sulfuric acid. The composite materials prepared in this study are more suitable than other materials for producing the current collectors. The corrosion resistance of composite materials is much better than that of the graphite, and the mechanism is also discussed.
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