Li Yue, Zhang Guoqiang, Song Shaofeng, Xu Haijun, Pan Mingwang, Zhong Gan-Ji
Institute of Polymer Science and Engineering, Hebei University of Technology, Tianjin 300130, China.
College of Polymer Science and Engineering, Sichuan University, Chengdu 610065, Sichuan, China.
Polymers (Basel). 2017 Sep 14;9(9):448. doi: 10.3390/polym9090448.
In the past few decades, Poly(vinylidene fluoride)/Polymethylmethacrylate (PVDF/PMMA) binary blend has attracted substantial attention in the scientific community due to possible intriguing mechanical, optical and ferroelectric properties that are closely related to its multiple crystal structures/phases. However, the effect of PMMA phase on the polymorphism of PVDF, especially the relationship between miscibility and polymorphism, remains an open question and is not yet fully understood. In this work, three series of particle blends with varied levels of miscibility between PVDF and PMMA were prepared via seeded emulsion polymerization: PVDF⁻PMMA core⁻shell particle (PVDF@PMMA) with high miscibility; PVDF/PMMA latex blend with modest miscibility; and PVDF@c⁻PMMA (crosslinked PMMA) core⁻shell particle with negligible miscibility. The difference in miscibility, and the corresponding morphology and polymorphism were systematically studied to correlate the PMMA/PVDF miscibility with PVDF polymorphism. It is of interest to observe that the formation of polar β/γ phase during melt crystallization could be governed in two ways: dipole⁻dipole interaction and fast crystallization. For PVDF@PMMA and PVDF/PMMA systems, in which fast crystallization was unlikely triggered, higher content of β/γ phase, and intense suppression of crystallization temperature and capacity were observed in PVDF@PMMA, because high miscibility favored a higher intensity of overall dipole⁻dipole interaction and a longer interaction time. For PVDF@c⁻PMMA system, after a complete coverage of PVDF seeds by PMMA shells, nearly pure β/γ phase was obtained owing to the fast homogeneous nucleation. This is the first report that high miscibility between PVDF and PMMA could favor the formation of β/γ phase.
在过去几十年中，聚偏氟乙烯/聚甲基丙烯酸甲酯（PVDF/PMMA）二元共混物因其可能具有的与多种晶体结构/相密切相关的有趣机械、光学和铁电性能而在科学界引起了广泛关注。然而，PMMA相对PVDF多晶型性的影响，尤其是互溶性与多晶型性之间的关系，仍然是一个悬而未决的问题，尚未得到充分理解。在这项工作中，通过种子乳液聚合制备了三组PVDF和PMMA之间具有不同互溶程度的颗粒共混物：具有高互溶性的PVDF⁻PMMA核⁻壳颗粒（PVDF@PMMA）；具有适度互溶性的PVDF/PMMA乳胶共混物；以及互溶性可忽略不计的PVDF@c⁻PMMA（交联PMMA）核⁻壳颗粒。系统地研究了互溶性差异以及相应的形态和多晶型性，以关联PMMA/PVDF互溶性与PVDF多晶型性。有趣的是，观察到在熔融结晶过程中极性β/γ相的形成可以通过两种方式控制：偶极⁻偶极相互作用和快速结晶。对于PVDF@PMMA和PVDF/PMMA体系，其中不太可能引发快速结晶，在PVDF@PMMA中观察到β/γ相含量更高，并且结晶温度和结晶能力受到强烈抑制，因为高互溶性有利于更高强度的整体偶极⁻偶极相互作用和更长的相互作用时间。对于PVDF@c⁻PMMA体系，在PMMA壳完全覆盖PVDF种子后，由于快速均匀成核，获得了几乎纯的β/γ相。这是第一份关于PVDF和PMMA之间的高互溶性有利于β/γ相形成的报告。
