Reinforcement of the optical, electrical and dielectric properties of PVC/ PS/PMMA ternary blend by the sol-gel derived nano-sized TiO2 for high-performance optoelectronic and energy storage applications

Nanoceramic filler-polymer hybrids of tunable optical and electrical characteristics are classified as polymer nanodielectrics due to their applications in promoting flexible-type advanced optoelectronic and organoelectronic devices. In the current work, high purity titanium oxide nanoparticles (TiO2 NPs) were produced through a facile sol-gel method and incorporated with concentrations of 1.0, 2.5 and 4.0 wt% into a ternary polymer blend matrix of polyvinyl chloride/polystyrene/polymethyl methacrylate (PVC/PS/PMMA) by the solution casting method. TEM indicated cubic and spherical NPs with an average particle size 15.57 +/- 0.94 nm which was very close to their calculated crystallite size by XRD technique. Also, XRD and FT-IR spectra showed the alteration of amorphous nature of PVC/PS/PMMA blend and the making of polymer-nanoparticle interactions due to the added nanofiller. SEM images showed a PVC/PS/PMMA blend with smooth and uniform surface and TiO2 NPs were well dispersed on the surface at low concentration. The optical absorption was investigated by UV/vis spectrophotometry and the optical constants (optical bandgap, Urbach energy and refractive index) were calculated. These films showed a dual-bandgap structure, and the direct (indirect) bandgap ranged from 4.11 to 3.5 eV (2.82 to 1.67 eV). These polymer nanocomposites showed TiO2 concentration dependent AC conductivity and dielectric permittivity in the range of 0.1 Hz-20 MHz of frequency. The relaxation process and the interfacial polarization effect of these nanocomposites were discussed. At 10 Hz, the dielectric constant significantly enhanced from 1.42 to 2.34 and AC conductivity increased from 9.12 x 10-13 S/ m to 2.19 x 10-13 S/m, after loading 4.0 wt% TiO2 NPs. The obtained results imply the multifunctionality of these nanocomposites for UV-blockers, optical bandgap tuners, and optical coatings in developing numerous advanced organoelectronic/optoelectronic devices, and also their use as high permittivity tunable nanodielectric substrates to promote the next-generation energy storage devices of high performance.