title: Exchange coupling in P(VDF-TrFE) copolymer based all-organic composites with giant electrostriction.
abstract: In this Letter, we discuss the dramatically enhanced electrostriction and dielectric constant in an all-organic composite consisting of polyvinylidene fluoride trifluoroethylene [P(VDF-TrFE)] copolymer matrix and copper-phthalocyanine (CuPc) particles, which could not be explained by traditional composite theory. Using a Landau-type potential energy combined with energy minimization, we demonstrate that the dramatic property enhancement is due to the exchange coupling between the dielectrically hard P(VDF-TrFE) and dielectrically soft CuPc, which becomes dominant when the heterogeneity size of the composite is comparable to the exchange length. The exchange coupling is a very effective mechanism for the enhancement of functional properties in ferroelectric and dielectric systems, and its variation with various material parameters is demonstrated and discussed.
authors.affiliation: Department of Engineering Mechanics, University of Nebraska-Lincoln, Lincoln, Nebraska 68588-0526, USA.
authors.forename: JiangYu
authors.initials: J
authors.lastname: Li