Can Relaxor Ferroelectric Behavior Be Realized for Poly(vinylidene fluoride-co-chlorotrifluoroethylene) [P(VDF–CTFE)] Random Copolymers by Inclusion of CTFE Units in PVDF Crystals?

• DOI: 10.1021/acs.macromol.8b01155
• Publication Date: 2018-07-13T18:17:03Z
• Authors: Yanfei Huang; Jia-Zhuang Xu; Thibaut Soulestin; Fabrice Domingues...; Ruipeng Li; Masafumi Fukuto; Jun Lei; Gan-Ji Zhong; Zhong-Ming Li; Yue Li; Lei Zhu
• Keywords: Chlorotrifluoroethylene; Ferroelectric Polymers; Hysteresis; Hexafluoropropylene; Electrostriction; Electroactive polymers

Relaxor ferroelectric (RFE) polymers are attractive for various electrical applications such as electrostrictive actuation, electromechanical sensors, electric energy storage, and electrocaloric cooling because of their high dielectric constants low hysteresis loss. Current state-of-the-art RFE include poly(vinylidene fluoride-co-trifluoroethylene) [P(VDF–TrFE)]-based random copolymers terpolymers. However, the costs due to a safety concern TrFE make near-term commercialization difficult. It is highly desirable explore opportunity TrFE-free PVDF [e.g., P(VDF–CTFE); CTFE chlorotrifluoroethylene] achieve behavior by inclusion in crystals (i.e., isomorphism). In this work, two strategies were employed crystals. First, high-pressure crystallization was used obtain extended-chain via pseudohexagonal paraelectric phase. Structural analyses indicated that units largely excluded from γ unit cells domains but located kinks inside lamellae. As result, no observed large domains. The second strategy utilized mechanical stretching at temperatures (−20 0 °C) oriented small β crystallites (ca. 5–7 nm). cells, locating crystal–amorphous interfaces. Although loops became somewhat slimmer result crystallite sizes, with slim still not achieved. This study demonstrated too be included tightly packed whether α, γ, or future, it other smaller comonomer 1-chloro-1-fluoroethylene.