Ferroelectric terpolymers, based on semicrystalline VDF/TRFE/chloro-containing termonomers: Synthesis, electrical properties, and functionalization reactions

In this thesis, a new chemical method is performed, by incorporating the small amount (∼7 mol %) of the chloro-containing termonomers, including chlorotrifluoroethylene (CTFE), 1,1 and 1,2-chloro-fluoroethylene (CFE), 1-chloro-2,2-difluoro ethylene (CDFE), into VDF/TrFE copolymer chains. Along with this study, we also synthesize a functional fluoropolymer that contains the functional group on either one end or both ends, and their diblock or triblock copolymers. The long term objective is to utilize these reactive functional groups to connect fluoropolymer with other materials to further improve the electrical properties of the terpolymers.; A novel polymerization method involves a combination of a low temperature borane/oxygen initiator and a bulk polymerization process. This process allows the thorough mixing of all monomers during the terpolymerization reaction, resulting in the homogeneous distribution of the termonomer units in the polymer chain. A chloro-containing termonomers, especially CDFE and CTFE, having comparative reactivity ratios with VDF and TrFE, lead to terpolymers with relatively narrow molecular weight and composition distributions. The homogeneous incorporation of the chloro-containing termonomers in the VDF/TrFE copolymer chain is crucial in modifying its polymer chain conformation and crystal structure.; For the functionalization of fluoropolymer, the telechelic VDF/TrFE/chloro-containing terpolymers having functional (polar and reactive) terminal groups, and triblock copolymers containing a VDF/TrFE/chloro-containing terpolymer and functional polymers was developed. These telechelic and block polymers not only provide interactive properties but also preserve the existing desirable properties due to the undisturbed polymer backbone. Two chemical methods have been studied, including (i) the use of functional borane/oxygen initiators that carry functional groups and exhibit living radical polymerization mechanism, and (ii) the investigation of an improved iodine transfer polymerization (ITP) method to prepare telechelic fluoropolymers containing two terminal iodine groups. The former method although has some advantages in terms of ease and high purity of the polymer with the desirable reactive functional groups such as acetyl (can be converted to hydroxy group), silane and bromine groups, the polymerization yield is not very high due to the intramolecular interaction between the boron atom and the functional groups. The latter method, the iodine transfer polymerization (ITP), provides a very effective method with high yield, good catalyst efficiency, and well-defined telechelic polymer structure with two reactive terminal iodine functional groups on both chain ends. (Abstract shortened by UMI.)...