Influence of Titanium Dioxide Nanocrystallinity on Chitosan Biocomposite Films by Sol-Gel Casting Process on Optoelectrical Properties

Bio-nanocomposite films were prepared using chitosan, gelatin, and varying concentrations (0, 0.5, 1.0, 2.0, and 5.0 wt%) of nanoparticulate titanium dioxide (TiO2) in acetic acid via the casting process. The incorporation of TiO2 nanoparticles into bio-chitosan films resulted in enhanced ultraviolet absorption and improved physical, mechanical, and electrical properties. Moreover, bio-chitosan films with added TiO2 exhibited antimicrobial properties, enhancing the preservation of packaged products by preventing the growth of microorganisms. The bio-nanocomposite films with 1.0 wt% TiO2 demonstrated an electroactive response, bending at low electrical field strengths (250 V/mm), while the reference sample without added TiO2 bent at a higher electrical field strength (550 V/mm). This suggests their potential use in electroactive actuator applications, where controlled bending or movement is required. Among the various TiO2 concentrations tested, bio-chitosan nanocomposite films with 0.5% and 1.0 wt% TiO2 (Formulas 7 and 8) demonstrated favorable characteristics. These films (Formulas 7 and 8) exhibited an appealing appearance, absence of tear marks, low bulk density (0.91 ± 0.04 and 0.85 ± 0.18 g/cm3), satisfactory electomechanical response properties at 250 V/m (17.85 ± 2.58 and 61.48 ± 6.97), low percentage of shrinkage (59.95 ± 3.59 and 54.17 ± 9.28), high dielectric constant (1.80 ± 0.07 and 8.10 ± 0.73), and effective UV absorption compared to pure bio-chitosan film without and with gelatin (Formulas 1 and 6).