Synthesis and characterization of poly(trifluoroethylene-co-hexafluoropropylene) and the optical properties of its thin films

Copolymers of trifluoroethylene (TrFE) and hexafluoropropylene (HFP) were synthesized and characterized by various instrumental techniques. The maximum incorporation of HFP was 19.6 mol%. It was found that the reactivity ratios of TrFE and HFP were r TrFE =4.12 and r HFP ≈0, respectively, by applying Mayo-Lewis method. It was also found that the incorporation of HFP in copolymer chain influenced thermal properties. As increasing HFP content in copolymers, the melting temperature and crystallinity of copolymers were decreased and the glass transition temperature of copolymers gradually shifted to low temperature. Reduced crystallinity of copolymers was helpful to prepare coating layers having much even surface. Compared with coating layer prepared from TrFE homopolymer, the surface roughness was decreased and light transmittance through the coating layer increased when the copolymers of TrFE and HFP were used. This tendency was more appreciable as increasing HFP content in the copolymers.