Copolymerizations of tetrafluoroethylene and perfluoropropylvinyl ether in supercritical carbon dioxide: Polymer synthesis, characterization, and thermal properties
Copolymerizations of tetrafluoroethylene and perfluoropropylvinyl ether in supercritical carbon dioxide: Polymer synthesis, characterization, and thermal properties
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DOI：
10.1002/app.35187
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发表时间：
2012-05
影响因子：
3
通讯作者：
A. Xu;W. Yuan;Junhong Zhao;Hong Li;Heng Zhang;Yongming Zhang
中科院分区：
文献类型：
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作者：
A. Xu;W. Yuan;Junhong Zhao;Hong Li;Heng Zhang;Yongming Zhang
在超临界二氧化碳(sc-CO2)中，以全氟-2-丙氧基丙酰基过氧化氢(BPPP)为引发剂，研究了四氟乙烯(TFE)和全氟丙基乙烯基醚(PPVE)的共聚反应。所合成的共聚物具有稳定的全氟烷基端基，避免了加工和应用过程中的分解。首次报道了TFE和PPVE的竞聚率。RTFE和rPPVE值分别约为8和0.08。这些参数对通过TFE和PPVE共聚改性PTFE具有重要意义。结果表明，当反应压力从8.5 Mpa增加到25 Mpa时，rTFE增加12.0%，rPPVE降低9.0%，这主要归因于高压下CO2的极性增强。因为TFE的反应活性比PPVE高两个数量级；一方面，共聚反应速率随着TFE投料比的降低而迅速下降；另一方面，共聚产物中的TFe含量随着反应时间的延长而下降。所有含有不同组分的PPVE的共聚物都具有出色的热稳定性。差示扫描量热仪(DSC)结果表明，受全氟丙基侧链基团的干扰，存在分子高度规则排列和链状堆积较少两种形式的晶体。(C)2011年威利期刊公司J Appl Polym Sci，2012
Tetrafluoroethylene (TFE) and perfluoropropylvinyl ether (PPVE) were copolymerized in supercritical carbon dioxide (sc-CO2) with a perfluorodiacyl initiator bis(perfluoro-2-n-propoxypropionyl) peroxide (BPPP). The resultant copolymers with stable perfluoroalkyl end groups were obtained, avoiding the decomposition during processing and applications. Reactivity ratios of TFE and PPVE were first reported. The rTFE and rPPVE values are about 8 and 0.08, respectively. Such parameters are significant for the modification of PTFE through copolymerization of TFE and PPVE. It is found that through increasing the reaction pressure from 8.5 to 25 MPa, while rTFE increases by 12.0%, rPPVE decreases by 9.0%, which should be ascribed to the enhancement of the polarity of CO2 under high pressures. Because the reactivity of TFE is by two orders of magnitude higher than that of PPVE; on one hand, the copolymerization rate falls rapidly with the decrease of TFE feed ratio; on the other hand, TFE content in the copolymer decreases with the reaction time. All copolymers containing different fractions of PPVE enjoy outstanding thermal stability. The DSC result indicates that there exist two forms of crystals with highly regular molecular arrangement or less ordered chain packing which is disturbed by perfluoropropyl pendants. (C) 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012