Controlling the crystalline nature and optical properties of PVA by adding CS as a modifier

Document Type : Research and Reference

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Physics Department, Faculty of Science, Tanta University, Tanta, Egypt

Abstract

This study uniquely explores the systematic tuning of optical band gaps in PVA/CS polymer blends by varying chitosan concentrations, correlating structural amorphous phase changes with precise optical property modifications. This approach offers new insights for optimizing polymer blends for optoelectronic and solar energy applications.
In this study, polyvinyl alcohol (PVA) and chitosan (CS) polymer blend was prepared using the solvent casting technique. The resulting films were characterized by X-ray diffraction (XRD), ultraviolet–visible (UV–Vis) spectroscopy, and Fourier-transform infrared (FTIR) spectroscopy were utilized to characterize the samples. XRD analysis was specifically used to examine the structural properties and to verify the presence of an amorphous phase. UV-Vis measurements revealed a declining pattern in the optical band gap conjunction with increasing CS content. The direct band gap decreased from 4.77 eV for pure PVA to 4.56 eV, 4.58 eV, and 4.36 eV for CS concentrations of 20%, 50%, and 80%, respectively, and further to 4.02 eV for pure CS. A similar decreasing trend was observed for the indirect band gap, which dropped from 5.27 eV for pure PVA to 4.09 eV for pure CS. These results indicate that the controlled modification of crystallinity and optical band gap via chitosan blending makes the PVA/CS films promising candidates for optoelectronic and solar energy-related applications.

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