Abstract
A novel quaternized polysulfone with N-dimethylethylammonium chloride (DMEA) and N-dimethyloctylammonium chloride (DMOA) pendent groups was investigated, as to its optical and electronic properties. Optical properties were investigated by refractivity and transmission spectra. To obtain the optical parameters, the approach proposed by Tauc for amorphous semiconductors has been used, because of the similarity of the absorption edges. The values of pseudogap energy ranged between 3.60 and 3.69 eV, while those of Urbach energy were modified over the 157-172 meV range. The dielectric properties and ac-conductivity were also studied as a function of temperature, frequency and structure of pendant groups. It was observed that the dielectric constant decreased as the frequency increased and the temperature decreased. In addition, quaternized polysulfone films were characterized by two relaxation processes, i.e., gamma and beta relaxation, which appeared at different temperatures, depending on the pendant groups. The frequency-temperature-dependent conductivity showed that conductivity increased with frequency and also that the quaternized polysulfones possessed typical semiconducting properties. All parameters were found to be slightly influenced by the polymer chain structure.