Large intrinsic piezoelectricity in intramolecular modified relaxor ferroelectric polymers near the morphotropic phase boundary
Authors: Ze Yuan, Yuquan Liu, Zekai Fei, Yutie Gong, Zhigao Huang, Yang Li, Chenyi Li, Yun Zhang, Huamin Zhou, Yang Liu
Piezoelectric materials interconvert mechanical and electrical energy, but piezoceramics are brittle while PVDF-based ferroelectric polymers exhibit low piezoelectric coefficients (d33 ≈ -30 pC N-1). Chemical modification via morphotropic phase boundary (MPB) engineering has raised d33 in P(VDF-TrFE) to -63.5 pC N-1, and to -69 pC N-1 with stretching, but intrinsic piezoelectricity in relaxor terpolymers remains limited. Here, relaxor ferroelectric P(VDF-TrFE-CFE) with varying C=C double bond (DB) content is synthesized via dehydrochlorination. Structural and electrical characterization reveals that increasing DB content stabilizes long-range ferroelectric order while suppressing short-range relaxor characteristics, forming a trans/helix phase boundary. At a critical DB content of 2.0 mol%, a markedly enhanced intrinsic d33 of -129.0 pC N-1 is achieved, outperforming previous MPB approaches. This finding addresses the fundamental bottleneck of low piezoelectric response in flexible ferroelectric polymers and provides a viable route for high-performance wearable electromechanical devices.