Spectroscopic and Thermal Studies of Polyalkoxysilanes and Silica-Chitosan Hybrid Materials

Abstract

Polymers of organoalkoxysilanes (or polyalkoxysilanes) were synthesized through sol-gel process using different organosilanes: Tetraethylorthosilicate (TEOS), (3-Glycidyloxypropyl) trimethoxysilane (GPTMS), Trimethoxy(propyl)silane (TMPS), and/or Triethoxy(octyl)silane (EOS). Different carboxylic acids (acetic, formic, and citric) were used to prepare polyalkoxysilanes, with citric acid acting as a reactant rather than a catalyst for the sol-gel reaction. Silica-chitosan hybrid materials were synthesized reacting polyalkoxysilanes and chitosan, one of the most important and most studied natural polymers, through sol-gel process. The synthesized materials were characterized using Fourier transform infrared spectroscopy (FT-IR), thermogravimetrical analysis (TGA), differential Scanning Calorimetric (DSC) and solid-state Carbon-13 Nuclear Magnetic Resonance (solid-state   13C-NMR) spectroscopy, obtaining information on the structural properties of each modified materials. The results obtained by NMR indicate that the oxirane group of GPTMS remains in all reaction products to form different polyalkoxysilanes.