Investigating structural changes of Chitosan-TiO2 and Chitosan-TiO2-ZnO-MgO hybrid films during storage by FTIR spectroscopy

Abstract

This work aimed to evaluate the effect of time and two storage temperatures (25 °C and 4 °C) on the structural changes in chitosan (CS) films functionalized with titanium dioxide (TiO2) and a ternary mixed oxide-based TiO2 (TiO2-ZnO-MgO; TZM) by Fourier transform infrared (FTIR) spectroscopy and the in vitro release of TiO2 and TZM from the CS film to the medium. Changes in the FTIR spectra (mainly in the 1700 to 1250 cm–1 region) of the CS-based films during storage were dependent on the storage temperature. The film stored at 25 °C showed remarkable changes after 7 days of evaluation, indicating a dehydration process; however, films stored at 4 °C exhibited reduced changes after 21 days of storage. Moreover, the migration behavior of TiO2 (< 13%) and TZM (< 7%) from CS to the medium showed a first-order kinetic model (R2 > 0.93) in a temperature-dependent response. Further studies are needed to correlate the structural changes of CSTiO2 and CSTZM films during storage with their technological and functional properties, which could limit their potential applications.