Cellulose derivative/barium titanate composites with high refractive index, conductivity and energy density

This work deals with hydroxypropyl cellulose (HPC)/barium titanate (BT) composites, having small levels of perovskite-like BT loading, i.e. 0.5-2% and being designed for electric energy storage applications. The films were obtained by solution casting method and their structural properties were confirmed by FTIR. Scanning Electron Microscopy scans reveal that ceramic filler is well and uniformly dispersed within the cellulosic matrix. UV-VIS spectroscopy data indicate a slight increase of the absorption and the decrease of optical band gap from 5.71 eV for the HPC matrix (0% BT) to 5.20 for the sample containing 2% BT. According to refractometry analyses, the presence of BT particles determines an increase in sample polarizability, reflected in a higher refractive index, namely 1.533 and 1.605 at 486 nm for 0% BT and 2% BT samples, respectively. The values of the dispersion energy and single-oscillator energy are decreasing after filling HPC with BT, whereas first/third order optical susceptibilities and nonlinear refractive index are increasing. Mechanical tests show that incorporation of BT particles increase the value of Young modulus from 239 MPa for pure HPC to 342 MPa for 2% BT in the matrix. Dielectric studies prove that the samples exhibit a significant change in the real part of the permittivity with filler loading, ranging from 4.2 for neat HPC up to 8.5 for HPC/BT 2%.

Automated summary

This study investigates hydroxypropyl cellulose/barium titanate composites for electric energy storage applications. The results show that the incorporation of barium titanate particles improves the structural, optical, mechanical, and dielectric properties of the films.