A polymer blend approach to tailor the ferroelectric responses in P(VDF-TrFE) based copolymers

The electroactive properties of PVDF-based ferroelectric polymers can be tailored by blending. In order to investigate the tunability of electrocaloric effect (ECE) and ferroelectric responses, blends of ferroelectric relaxor poly(vinylidene difluoride-trifluoroethylene-chlorofluoroethylene) (P(VDF-TrFE-CFE)) terpolymer and normal ferroelectrics poly(vinylidene difluoride-co-trifluoroethylene) (P(VDF-TrFE)) copolymer are studied. At low copolymer content (<15 wt%), the coupling between the relaxor terpolymer and the nano-phase copolymer converts the copolymer into relaxor and causes an increase in the crystallinity compared with neat terpolymer. As a result, the blends exhibit an enhanced relaxor polarization response and a significant increase in the electrocaloric effect compared with those in the neat terpolymer. At high copolymer content, the blends exhibit mixed structures of the two components. By varying composition, the dielectric and ferroelectric properties of blends can be tuned in the range between the copolymer and terpolymer. This blend system provides a model system to study how random defects influence the polarization response in the normal ferroelectric copolymer, and to understand the relationship between the polarization response and ECE in the blends. The results demonstrate the promise of nanocomposite approaches in tailoring and enhancing ECE and ferroelectric properties in the ferroelectric polymers.