Physico‐Chemical Understanding of Plasticizers Interaction with P(VDF‐TrFE‐CFE) Electroactive Polymer

ABSTRACT The introduction of plasticizers in P(VDF‐TrFE‐CFE), a relaxor ferroelectric polymer, has shown major improvements over the past few years. The drastic gains in softness and dielectric permittivity at low frequency are undeniably relevant for actuation, but the interactions involved in such mechanism remain unclear. A parametric study of the terpolymer composition on its interaction with di‐n‐octyl phthalate (DNOP) is investigated here. In combination with a room‐temperature Curie‐like transition obtained for VDF/(VDF+TrFE) ratio below two‐thirds, a large proportion of TrFE, contrary to CTFE‐based terpolymers, leads to plasticized films of Young's moduli below 50 MPa. It was disclosed by FTIR that the amount of termonomer triggers the retention of DNOP, here theorized by electrostatic interactions, in accordance with the saturation of the mechanical properties for low‐CFE content terpolymers. For the first time, this study unveils a close synergy between chemical affinity and physical properties of plasticized terpolymers. As a result, an extremely soft, crack‐free terpolymer film (Y = 17.6 MPa) was successfully synthesized with 20 wt.% of DNOP. Although its electrical breakdown strength is undoubtedly affected, a combination of high molecular weight and purity unlocks great potential for substantial, low‐powered displacements of 4D‐printed multilayer actuators.