The effect of chain structures on the crystallization behavior and membrane formation of poly(vinylidene fluoride) copolymers

Wenzhong Ma; Haoge Yuan; Xiaolin Wang

doi:10.3390/membranes4020243

The effect of chain structures on the crystallization behavior and membrane formation of poly(vinylidene fluoride) copolymers

Membranes (Basel). 2014 May 19;4(2):243-56. doi: 10.3390/membranes4020243.

Authors

Wenzhong Ma¹, Haoge Yuan², Xiaolin Wang³

Affiliations

¹ Beijing Key Laboratory of Membrane Materials and Engineering, Department of Chemical Engineering, Tsinghua University, 1 Tsinghuayuan, Beijing 100084, China. wenzhong-ma@cczu.edu.cn.
² Beijing Key Laboratory of Membrane Materials and Engineering, Department of Chemical Engineering, Tsinghua University, 1 Tsinghuayuan, Beijing 100084, China. yhg12@mails.tsinghua.edu.cn.
³ Beijing Key Laboratory of Membrane Materials and Engineering, Department of Chemical Engineering, Tsinghua University, 1 Tsinghuayuan, Beijing 100084, China. xl-wang@tsinghua.edu.cn.

Abstract

The crystallization behaviors of two copolymers of PVDF were studied, and the effect of copolymerized chains on the crystallization behavior was investigated. The results indicated that both copolymers had a lowered crystallization temperature and crystallinity. The crystallization rate was improved by the copolymer with symmetrical units in PVDF chains, but hindered by asymmetrical units, compared with the neat PVDF. The symmetrical units in PVDF chains favored the β-crystals with fiber-like structures. According to the solubility parameter rule, methyl salicylate (MS) can be chosen as a diluent for PVDF copolymers. Both diluted systems had liquid-liquid (L-L) regions in the phase diagrams, which was due to the lowered crystallization temperature.