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Yu Y.,The Key Laboratory of Molecular Engineering of Polymers | Zhong X.,The Key Laboratory of Molecular Engineering of Polymers | Su H.,The Key Laboratory of Molecular Engineering of Polymers | Serra A.,Rovira i Virgili University
Polymer | Year: 2010

Polyoxometalate exhibits high catalytic performance for the simultaneous cationic polymerization and esterification of epoxy resin when anhydride is introduced as a co-hardener. The selective catalysis effect of polyoxometalate and the reaction mechanism was studied by differential scanning calorimetry (DSC), mid-infrared spectroscopy (MIR), near-infrared spectroscopy (NIR) and generalized two-dimensional correlation analysis. The cationic polymerization is the dominating reaction in neat epoxy systems. Increasing the amount of polyoxometalate and the polarity of the diluents fastens the curing rate of epoxy resin. Esterification was found to be the preferred reaction once anhydride was employed. When polyoxometalate was blocked by amine to form salt, it performs as an excellent catalyst for esterification in epoxy-anhydride systems. The epoxy materials catalyzed by polyoxometalate show quite good performance compared with ordinary epoxy resins. Moreover, thermal degradation analysis (TGA) shows that polyoxometalate could significantly decrease the thermal degradation temperatures of cured epoxy resins. © 2010 Elsevier Ltd. All rights reserved.


He M.,The Key Laboratory of Molecular Engineering of Polymers | Ge J.,The Key Laboratory of Molecular Engineering of Polymers | Fang M.,The Key Laboratory of Molecular Engineering of Polymers | Qiu F.,The Key Laboratory of Molecular Engineering of Polymers | Yang Y.,The Key Laboratory of Molecular Engineering of Polymers
Polymer | Year: 2010

A facile template-free approach to fabricate poly(3-hexylthiophene) (P3HT) into highly aligned microwire film on a large scale via the evaporation of P3HT/Anisole whisker solution has been developed. The microwires in the film typically have the height of 0.8-1.4 μm, width of 2-4 μm and length of 50-1000 μm. X-ray Diffraction and Selected-Area Electron Diffraction results suggest that each microwire is a single crystal with the reduced packing distance of P3HT chains along the π-π stacking direction (d[010] of 6.5 Å) and the interchain direction (d[100] of 15.7 Å). The closer packing of P3HT chains is likely the key factor promoting the formation of the highly aligned microwires. The aligned P3HT microwire films perform enhanced electrical conductivity, and show no substrate dependence, thus can be fabricated into organic electronic devices in situ. © 2010 Elsevier Ltd. All rights reserved.


Lai H.,The Key Laboratory of Molecular Engineering of Polymers | Wu P.,The Key Laboratory of Molecular Engineering of Polymers
Polymer | Year: 2010

FTIR in combination with perturbation correlation moving window (PCMW) technique was applied to study the phase transition of concentrated aqueous solutions of Poly(N-isopropylacrylamide) (PNIPAM) and its small molecular model compound N-isopropylpropionamide(NIPPA). It was found that lower critical solution temperature (LSCT) of 40% NIPPA/D2O solution was 39 °C which was higher by ca. 8 °C than that of PNIPAM, and that NIPPA exhibited much wider temperature ranges of phase transition from 30 to 50 °C while PNIPAM underwent the phase separation in a narrow temperature range (29.1-33.1 °C). Moreover, we utilized two-dimensional correlation infrared spectroscopy (2DIR) analysis to reveal that the presence of main chains didn't affect the sensitivity and changing sequence of different groups, but did have a strong effect on the size of aggregation and formation of hydrogen bonds between carbonyl groups and water molecules. Without the interference of hydrophobic main chains, the carbonyls of NIPPA (1600 cm-1) could interact with more water than those of PNIPAM (1627 cm-1) below LSCT, which was the reason of the slower and milder phase transition taking place in NIPPA system. © 2010 Elsevier Ltd. All rights reserved.

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