Laboratory of Advanced Polymer MaterialsInstitute of Chemistry

Laboratory of, China

Laboratory of Advanced Polymer MaterialsInstitute of Chemistry

Laboratory of, China
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Yuan L.,Chinese Academy of SciencesZhongguancun | Ji M.,Laboratory of Advanced Polymer MaterialsInstitute of Chemistry | Yang S.,Laboratory of Advanced Polymer MaterialsInstitute of Chemistry
Journal of Applied Polymer Science | Year: 2017

To investigate the effect of reactive end-capping groups on film-forming quality and processability, a series of molecular weight-controlled aromatic poly(amic acid) (PAA) resins functionalized with phenylethynyl end groups were prepared via the polycondensation of 3,3',4,4'-biphenyltetracarboxylic dianhydride (BPDA), para-phenylenediamine (PDA), and 4-phenylethynyl phthalic anhydride (PEPA) served as molecular-weight-controlling and reactive end capping agent. The PAA resins with relatively high concentrations endow enhanced wetting/spreading ability to form PAA gel films by solution-cast method which were thermally converted to the fully-cured polyimide (PI) films. The mechanical and thermal properties of PI films were investigated as a function of PAA molecular weights (Mn) and thermal-curing parameters. Mechanical property, dimensional stability and heat resistance of the fully-cured PI films with PAA Mn>20 ×103 g mol-1 are found to be better than that of their unreactive phthalic end-capped counterparts. The covalent incorporation of chain-extension structures in the backbones, induced by thermal curing of phenylethynyl groups, might facilitate yielding a higher degree of polymer chain order and consequently improved resistance strength and elongation at break to tensile plastic deformation. © 2017 Wiley Periodicals, Inc.


Fei H.-F.,Chinese Academy of SciencesBeijing | Gao X.,Laboratory of Advanced Polymer MaterialsInstitute of Chemistry | Han X.,Chinese Academy of SciencesBeijing | Wang Q.,Laboratory of Advanced Polymer MaterialsInstitute of Chemistry | And 3 more authors.
Journal of Polymer Science, Part A: Polymer Chemistry | Year: 2015

Novel fluorine containing siloxane monomer, namely, 4-trifluoromethylphenylmethyl cyclosiloxane (PF3) and mixed cyclosiloxane including both 4-trifluoromethylphenylmethyl siloxane (P) unit and trifluoropropyl siloxane (F) unit were successfully synthesized in this study. Furthermore, their series including vinyl-terminated copolymers with different compositions were synthesized. The microstructures of copolymers were investigated by 1H NMR, 29Si NMR, 19F NMR, Fourier transform infrared spectroscopy, and differential scanning calorimetry (DSC). The results of characterizations confirmed that the copolymers exhibited random microstructure. Moreover, the analysis of the result of DSC also revealed that the copolymers had a low glass transition temperature. The thermogravimetric analysis indicated that poly(4-trifluoromethylphenylmethyl)siloxane (PPF3) exhibited higher thermal stability than conventional fluorosilicones rubber (FSR). The dynamic mechanical analysis showed that the damping factors of these copolymers were greater than 0.3 in a wide range of temperature. The mass swelling ratios were less than 5.5% when the samples were immersed in No. 3 jet fuel for a month. © 2015 Wiley Periodicals, Inc.

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