Low-frequency dielectric response and chain dynamics study of poly(vinyl pyrrolidone)–poly(ethylene glycol) coexisting two-phase polymeric blends

Abstract

317-323The dielectric response of various concentration poly(vinyl pyrrolidone)-poly(ethylene glycol) (PVP–PEG) blends with change in polymer chain-length and their different volume mixtures over the entire concentration range were investigated in the frequency range 20 Hz-1 MHz at 25ºC. The complex dielectric constant ε*(ω), complex electric modulus M*(ω), complex impedance Z*(ω), and a.c. conductivity data were used for the confirmation of the electrode polarization effect, ionic conduction and the micro-Brownian motion of the PVP chain (m-process) in the PVP–PEG blends. All the blends show the dielectric dispersion corresponding to the PVP segmental motion in the upper experimental frequency range whereas in the lower frequency side of the spectra has dielectric dispersion is due to ionic conduction and electrode polarization. The different volume mixtures of some of the different chain-length PVP–PEG blends also shows the polymer chain-length and concentration dependence m-process. All the blends show the d.c. conductivity behaviour in the lower frequency region, which is little affected by the blends composition. The appearance of two separate arcs in the complex impedance plane plots confirms the contribution of nickel-plated cobal electrodes polarization effect to the values of complex dielectric constant of the PVP–PEG blends in the lower frequency range up to 500 Hz