FeCl3-doped polyvinylidene fluoride

Abstract

Infrared (350-4000 cm -1) and optical (1.1 5 x 1 04 - 2.95 x 1 04 cm -1) spectra, differential thermal analysis (DTA) and d.c. electrical resistivity of FeCI3- doped polyvinylidene fluoride (PVDF) films, over the doping mass fraction range 0 ~< w ~< 0.40, have been measured. The i.r. spectra provided evidence of: (a) the presence of both ~ and y phases in the undoped, and a y phase in the doped PVDF films; (b) a head-to-head content of 20%; and (c) a different doping mode beyond a 0.25 doping level. The optical spectra resulted in two induced energy bands, and a probable interband electronic transition, due to doping. Dipole relaxation and premelting endothermic peaks were identified by DTA. Electrical conduction is thought to proceed by interpolaron hopping among the polaron and bipolaron states induced by doping. The hopping distance, R o, is calculated according to the Kuivalainen model. A numerical equation is adopted to formulate the dependence of R o on doping level and temperature. It is found that Ro < CC separation length. This implies that, in doped PVDF, charge carrier hopping is not an intrachain process.