Thermal, dielectric and optical studies on cellulose acetate butyrate-gold nanocomposite films prepared by laser ablation

Abstract

This work employed pulsed laser ablation to produce cellulose acetate butyrate-gold (CAB-Au) nanocomposite films and the evaluation of their structural and thermal characteristics using Raman, X-ray diffraction (XRD), thermogravimetric analysis (TGA), and Differential Scanning Calorimetry (DSC). In the frequency range 0.1–10 MHz, nanocomposite films' dielectric constant, loss, and electric modulus behavior were investigated as a function of temperature. The refractive index, finesse coefficient, Brewster coefficient, critical angles, dielectric function, and color properties of nanocomposite films were examined in the wavelength range 190–800 nm. X-ray diffraction shows a strong Au diffraction signal in all samples, confirming Au NPs. The SEM micrograph shows Au embedded in CAB. The CAB-Au nanocomposites had higher thermal stabilities (Tm) than pure CAB, and the DSC thermograms showed a fluctuating glass transition temperature due to the dynamics of organic-inorganic interactions in the nanocomposite films. Dielectric dispersion is caused by hidden dipolar polarization. The CAB (5 min) sample had the highest ac conductivity as a function of frequency at various temperatures as the Au content in the Au/CAB composite rose. The simplest quantum mechanical tunneling (QMT) model also best explains the ac conduction property. We found a relationship between the nanocomposites' refractive index and the amount (extent of incorporation) of Au in the materials, with laser irradiation time determining the various color constants. Tauc plots reveal a permitted transition with an optical energy gap of 5.1eV for the polymer film and 4.75eV after 10 and 20 min of laser irradiation.