Effect of Ormosil and Polymer Doping on the Morphology of Separately and Co-hydrolyzed Silica Films Formed by a Two-Step Aqueous Processing Method

Abstract

The entrapment of biomolecules within organic−inorganic nanocomposite materials derived by a sol−gel method has proven to be a viable route for the development of biosensors and biocatalysts. However, the phase separation behavior within nanocomposite materials formed by a protein-compatible two-step aqueous processing method is not well-understood. In this study, a range of imaging methods was used to assess the degree of heterogeneity in a series of dipcast thin films formed with different types and levels of ormosils in the presence and absence of polyethylene glycol (PEG), using both separate and co-hydrolysis of precursors. Both microscopic (bright-field and fluorescence microscopy) and nanoscale (atomic force microscopy and scanning electron microscopy) imaging demonstrate that short chain monofunctional ormosils such as methyltrimethoxysiline do not lead to significant heterogeneity when mixed with TEOS, while disubstituted (dimethyldimethoxysilane) or longer chain (isobutyltrimethoxysilane) ormosi...