Piezoelectric fluorinated polymer composites: A review on coupling agents at the filler/matrix interface

Abstract

Among electroactive polymers, polyvinylidene fluorine (PVDF) and its copolymers present the highest piezoelectric response which makes them very attractive for applications combining flexibility and piezoelectricity. The use of composites with the incorporation of electroactive ceramics (with a very high piezoelectric coefficient compared to polymers) into the fluorinated polymer matrix allows for an increase in the material piezoelectric response while keeping ductility. The review presents in the first part an overview of the impact of the ceramic particle size and dimension and the filler content. In ceramic/polymer composites, the interface between both constituents is generally weak and has to be strengthened. This review summarizes in the second part different strategies used to improve the interface between the electroactive fillers and the piezoelectric fluorinated polymer matrix to increase the piezoelectric performance of composites. Molecular coupling agents (CAs) are presented and polymer‐based CAs synthesized from “grafting to” and “grafting from” techniques are described. In the last part, the combination of antiparallel poling of ceramic and polymer piezoelectric responses is reported in the composites and the potential of such materials for future development is finally discussed.Highlights Piezoelectric properties of composites with electroactive ceramic fillers in fluorinated polymer matrix are discussed. Different strategies used to improve the interface between electroactive fillers and piezoelectric fluorinated polymer matrix are presented. The synthesis of molecular CAs or polymer‐based CAs from “grafting to” or “grafting from” techniques is described. The piezoelectric response of ceramic/polymer composites poled in parallel and anti‐parallel are summarized. The antiparallel poling of electroactive ceramic and piezoelectric polymer contributions is a promising way to maximize piezoelectric performances.