Despite the wide industrial application of poly(tetrafluoroethylene-co-perfluoroalkylvinyl ether) (PFA) in semiconductor processing, its crystallization behavior has little been studied. In this work, three PFA resins with similar molecular weight but different comonomer content and distribution were synthetized. Then the non-isothermal crystallization kinetics and crystalline structures were studied by differential scanning calorimetry, polarizing optical microscopy, and X-ray diffraction systematically. It is found that the incorporation of comonomers destroys the chain regularity and reduces the crystallizability of PFA thermodynamically, while the comonomer insertion improves the chain flexibility to accelerate the crystal growth dynamically. When the comonomer content of PFA is low, both the nucleation and growth rates are quite fast, which is favorable for the formation of spherulite. As the comonomer content increases or distribute uniformly in the chain, the nucleation rate declines notably and the side groups distort the crystal cell to increase the spacing of [100] plane. Moreover, two-dimensional growth mode is dominant to form bundle-like structure when crystallizing at slow cooling, where nucleation is suppressed by growth. But three-dimensional symmetrical spherulite can be activated and perfected at high cooling rate due to the initiation of substantial nucleation sites. This unique crystallization behavior is opposite to that of conventional polymers, providing a guidance for the polymerization and processing of PFA.

中文翻译：

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分子结构和温度场对四氟乙烯-全氟烷基乙烯基醚共聚物结晶行为的影响


尽管聚（四氟乙烯-全氟烷基乙烯基醚）（PFA）在半导体加工中具有广泛的工业应用，但其结晶行为却很少被研究。在这项工作中，合成了三种分子量相似但共聚单体含量和分布不同的 PFA 树脂。然后通过差示扫描量热法、偏光显微镜和X射线衍射系统地研究了非等温结晶动力学和晶体结构。研究发现，共聚单体的引入破坏了链的规整性并在热力学上降低了PFA的结晶性，而共聚单体的插入则提高了链的柔性，从而动态地加速晶体生长。当PFA共聚单体含量较低时，成核和生长速率都较快，有利于球晶的形成。随着共聚单体含量增加或在链中分布均匀，成核率显着下降，侧基使晶胞扭曲，增加[100]面间距。此外，在缓慢冷却结晶时，二维生长模式占主导地位，形成束状结构，其中成核受到生长的抑制。但由于大量成核位点的引发，三维对称球晶可以在高冷却速率下被激活和完善。这种独特的结晶行为与传统聚合物的结晶行为相反，为PFA的聚合和加工提供了指导。