Synthesis of hybrid chitosan/calcium aluminosilicate using a sol-gel method for optical applications

•We show a large specific surface area of hybrid CS/calcium aluminosilicate thin films and membranes using sol-gel method.•Inorganic SiO2-based phase are perfectly embedded onto chitosan matrix has a reliable stability.•CS/calcium aluminosilicate could be usable for optical sensors, planar waveguide, and bio-sensing.

Hybrid chitosan (CS)/calcium aluminosilicate nanocomposites thin films and membranes were prepared using a sol–gel method with three different concentrations of Al2O3 (5, 7 and 10 mol. %). The prepared nanocomposites were characterized by transmission electron microscopy, X-ray diffraction and Fourier Transform Infrared spectroscopy. The optical properties of the prepared samples were analyzed by UV/Vis spectrophotometry and photoluminescence (PL) spectroscopy. The optical parameters revealed an increase in both the refractive index and band gap of the nanocomposites with increasing Al concentration. In addition, the PL spectra revealed a blue shift that was consistent with an increase in the optical band gap. These results suggest that CS/calcium aluminosilicate in two different forms can be a good candidate for optical sensors applications.

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