Infrared and X-ray photoelectron spectroscopy studies of hybrid organic/inorganic fast sol–gel glasses

Fast Sol–Gel (FSG) hybrid materials with varying organic residues were analyzed by Mid- and Near-Infrared (IR) spectroscopy, allowing identification of functional groups of the matrix composition. X-ray photoelectron spectroscopy (XPS) was used to analyze the atomic composition of the hybrids, showing good correlation to values calculated according to the starting precursors. Mid-IR spectral analysis of the glasses enables insight into polymerization and curing processes. It can thus be used to assess optical and mechanical performance of a variety of sol–gel based devices. Analysis of the broad band at 1920 nm allows the identification of three different water species; S0, S1 and S2 together with clustered water. The subscript numerical label applies to the number of hydrogens participating in bonding with the surface silanols. We suggest that the surface silanols exhibit different sites, each susceptible to a characteristic adsorption mode of a water molecule.In this work we show that the FSG hybrid material is very stable at elevated humidity environments, and is even resistant to water immersion. These properties could be beneficial for optical and mechanical applications for marine targeted devices or medical sensors operating in aqueous media.

► Production of optically transparent glassy hybrid materials with tunable properties. ► XPS allows analyzing the atomic composition of the hybrids. ► Mid-IR spectral analysis enables insight into polymerization and curing processes. ► NIR-IR analysis allows the identification of four different adsorbed water species. ► Surface silanols exhibit different sites of water molecule adsorption.