Reduced shrinkage of sol-gel derived silicas using sugar-based silsesquioxane precursors

Monolithic siliceous materials were prepared, using sol-gel based methods, from mixtures of trifunctional silanes based on sugar lactones, including silyl-modified gluconamide GLS and maltonamide MLS, and a tetrafunctional silane derived from glycerol. The tri- and tetrafunctional compounds cured at different rates, which led to an enhanced presence of sugar moieties at the external surface of the pores in the monoliths. The resulting silicas exhibited dramatically reduced degrees of shrinkage (< 10%) when compared to silica monoliths prepared in the absence of trifunctional silanes (up to 85%). The sugars also alter the morphology of the material, with significant reductions in both micropore volume and surface area for materials containing GLS. The reduced shrinkage, presence of sugars on the silica surface, and altered morphology are likely to be important factors in providing such materials with the ability to stabilize entrained proteins.