Electroactive behavior on demand in Poly(vinylidene fluoride-co-vinyl alcohol) copolymers

Abstract

Ferroelectric polymers, such as poly(vinylidene fluoride) (PVDF), are attractive electroactive materials that can be integrated in advanced electronic devices. Unfortunately, to obtain the ferroelectric phase in PVDF, additional processing methods or expensive copolymerizations with trifluoroethylene have to be employed. Moreover, the highly fluorinated polymers lack functionalities to gain improved properties, such as wettability and possibilities for crosslinking and nanoobject dispersion. In this work, the synthesis and electroactive behavior of poly(vinylidene fluoride-co-vinyl alcohol) (P(VDF-co-VA)) copolymers are demonstrated using a cheap vinyl acetate-based precursor. We show that the switching properties can be tuned by varying the vinyl alcohol content in the copolymers. Linear dielectric behavior is observed for copolymers with 10 mol % VA due to a mixture of α- and β-crystals. Intriguingly, the incorporation of 15 mol % VA results in the direct crystallization into the ferroelectric β-phase from the melt. Consequently, this P(VDF-co-VA) copolymer with hydroxyl functional groups in the polymer backbone is ferroelectric without additional processing and demonstrates a coercive field and a remnant polarization of 80 MV m−1 and 2.8 μC cm−2 at 200 MV m−1, respectively, showing its high potential for advanced electronic applications.