Comparative Study of Physical and Thermal Properties of Chitosan-Silica Hybrid Coatings Prepared by Sol-Gel Method

Organic-inorganic hybrid coatings have been prepared by sol-gel method of chitosan with different silanes. Silane precursors used in these coatings are glycidoxypropyltrimethoxysilane (GPTMS), Tetramethoxysilane (TEOS) and vinytrimethoxysilane (VTMS). The hybrid coatings have been evaluated by AT-FTIR and 13C-NMR analysis for their structural features, which confirms the formation of siloxane-polymer network and provide the evidence of different silanes used. An XRD result presents crystalline structure of chitosan-silica hybrid coatings. It illustrate that the aggregation of silica in hybrid coatings differs with the silane used in hybrid coatings. The structural modification occurring due to different silane precursors is responsible for more thermal stability of hybrid coatings than pristine chitosan. Differential scanning calorimetry (DSC) presents the glass transition temperature of hybrid coatings. The water wettability of hybrid coatings is measured by contact angle analysis. The contact angle values of hybrid coatings with respect to polar and non-polar solvent assures the surface reorganization during contact angle measurements. Surface energy explains the behavior of liquids on the hybrid coatings. The surface morphology and roughness of hybrid coatings are well explained by SEM and AFM studies. The wettability and surface morphology of hybrid coatings differ by the use of different silanes used in the hybrid coatings

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