Ionic and electronic transport in PSF/NiO and PSF/TiO2 polymer nanocomposites: A positron lifetime study

Abstract

Polymer nanocomposites of PSF/NiO and PSF/TiO2 with different wt% of nanofiller have been prepared and subjected to SEM, FTIR, X-ray diffraction, DSC, PALS and electrical conductivity measurements. The relationship between crystallinity, surface morphology, glass transition temperature, free volume and the electrical conductivity of these polymer nanocomposites was systematically investigated. The increased AC and DC electrical conductivity at the lower concentration of NiO suggests the increased number of mobile ions and electrical charge carriers due to the increased crystallinity of PSF/NiO composites. The decreased conductivity at higher concentration of NiO indicates the reduced conducting pathways for the mobility of ions and the electrical charge carriers due to the decreased crystallinity by the nanoparticles aggregations. The increased AC and DC electrical conductivity with increasing the concentration of TiO2 indicates more and more positive charges in front of the cathode, resulting proper polymer-nanofiller interface due to the conductivity chain formation through the nanoparticles aggregation. The surface morphology of PSF/NiO and PSF/TiO2 nanocomposites show dispersion of nanoparticles over the surface of PSF matrix and the formation of filler aggregates at higher wt% of nanofiller incorporation. The increased glass transition temperature (Tg) and decreased o-Ps lifetime (τ3) at the lower concentration of NiO and TiO2 indicates the improved interfacial interaction between the surface of NiO and TiO2 nanoparticles with the side chains of PSF polymer matrix. This is evident from Fourier Transform Infrared Spectroscopy (FTIR) studies. The increased o-Ps lifetime (τ3) at higher concentration of NiO and TiO2 suggests the increased interfacial space for o-Ps to annihilate at the interface of PSF and NiO and TiO2 nanoclusters.