Nonlinear optical and dielectric properties of TiO2 nanoparticles incorporated PEO/PVP blend matrix based multifunctional polymer nanocomposites

Abstract

Poly(ethylene oxide) (PEO)/poly(vinyl pyrrolidone) (PVP) blend (50/50 wt%) and mixed-phase (anatase and rutile) titanium dioxide (TiO2) nanoparticles are used as organic host matrix and inorganic nanofiller, respectively, for the preparation of hybrid polymer nanocomposite (PNC) films (i.e. (PEO/PVP)–x wt% TiO2; x = 0, 1, 3, 5, 10, and 15) by solution casting method with deionized water as solvent. These PNC films are characterized by employing SEM, FTIR, XRD, UV–Vis, DSC, and DRS techniques. The effect of TiO2 nanofiller loading on the structural, morphological, thermal, optical, dielectric, and electrical properties of the PEO/PVP blend matrix, and also on the chain segmental dynamics of PEO in the PNC structures is investigated. It is revealed that the crystalline phase and spherulite morphology of PEO, and the polymer–polymer interactions in these PNC films have been primarily modified by the polymer–nanoparticle interactions. The optical energy band gap decreases, whereas UV absorbance enhances non-linearly with the increase of TiO2 concentration in the PNC films. The enthalpy of melting of the PEO irregularly reduces when the incorporated amount of TiO2 enhances in these films. The real part of complex permittivity and the dielectric loss tangent of these materials are found frequency independent in the range from 20 kHz to 1 MHz but these parameters increase non-linearly from ~ 1.6 to 2 and 0.006–0.008, respectively with the increase of TiO2 concentration up to 10 wt%, at 30 °C. The dominant contribution of interfacial polarization process increases the real part of complex permittivity of these PNC materials by about 1.3 times with the decrease of frequency from 20 kHz to 20 Hz which further enhances with the increment in the temperature of the film. The electrical behaviour of these materials has been examined by analyzing their ac electrical conductivity, complex impedance, and electric modulus spectra over the frequency range 20 Hz–1 MHz. The dc electrical conductivity of these PNC materials enhances nonlinearly with the increase of TiO2 loading in the PEO/PVP blend matrix. The optical and dielectric parameters of these flexible-type PNC materials confirm their multifunctional properties as UV absorber, optical energy band gap tuner, low permittivity tunable nanodielectric, electrical conductivity regulator, and novel host matrix for ion conducting materials. The results infer that these innovative technologically advanced engineered materials can be potential candidates for the next generation microelectronic devices.