Fluorine-free strongly dipolar polymers exhibit tunable ferroelectricity.

Huang, Jiahao; Rui, Guanchun; Yan, Yueming; Allahyarov, Elshad; Kwok, Man-Hin; Zhu, Wenyi; Li, Li; Zhang, Shixian et al. · Science · 2025

basic_science · Level V

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Abstract

Current research on ferroelectric polymers centers predominantly on poly(vinylidene fluoride) (PVDF)-based fluoropolymers because of their superior performance. However, they are considered "forever chemicals" with environmental concerns. We describe a family of rationally designed fluorine-free ferroelectric polymers, featuring a polyoxypropylene main chain and disulfonyl alkyl side chains with a C3 spacer: -SO<sub>2</sub>CH<sub>2</sub>CHRCH<sub>2</sub>SO<sub>2</sub>- (R = -H or -CH<sub>3</sub>). Both experimental and simulation results demonstrate that strong dipole-dipole interactions between neighboring disulfonyl groups induce ferroelectric ordering in the condensed state, which can be tailored by changing the R group: ferroelectric for R = -H or relaxor ferroelectric for R = -CH<sub>3</sub>. At low electric fields, the relaxor polymer exhibits electroactuation and electrocaloric performance comparable with those of state-of-the-art PVDF-based tetrapolymers.