Effect of P-toluene sulphonic acid on the dielectric properties of poly(4-vinylpyridine)

Dielectric properties of P-toluene sulphonic acid (PTSA) doped poly(4-vinylpyridine) have been studied in the frequency range 50 Hz–100 KHz and temperature range 300–430 K. Dielectric constant (ε′) decreases with increasing frequency and remains almost constant at higher frequencies. There is an increase in constant value at temperatures especially near Tg of the complexes and pure polymer. With increase in the concentration of PTSA, dielectric constant increases and then decreases at higher concentration. The dissipation factor (ε″) decreases in the medium frequency range and increases at higher frequencies. With respect to temperature the dissipation factor (ε″) is very high near the Tg values of the complexes and pure polymer. For increasing concentration of dopant ε″ decreases and increases at higher concentration. The results are interpreted considering the dipole orientation, relaxation of functional groups and polymer chain segments. Effect of further doping with iodine is also studied. AC conductivity values are calculated from dielectric data and effect of temperature and frequency has been studied.