Development of Macroporous Titania Monoliths Using a Biocompatible Method. Part 1: Material Fabrication and Characterization

Monolithic titania could offer significant potential as a support for bioaffinity chromatography because of its stability, unlike silica, to a wide range of pH conditions and its ability to selectively bind phosphorylated proteins and peptides. However, traditional routes to monolithic titania utilize harsh conditions incompatible with most biomolecules. To address this, titania monoliths were prepared in a biocompatible sol−gel process from Ti(OiPr)4 and glycerol. Varied porosities could be introduced by the additional use of high-molecular-weight poly(ethylene oxide) in the sol, which led to the formation of two phases prior to gelation. Morphologies, including bimodal meso- and macroporous structures, and the polymerization of either the dispersed or condensed phases could be controlled by the fraction and molecular weight of PEO in the sol. The roles of glycerol and PEO are to retard hydrolysis and condensation reactions so that phase separation of titanium-rich species precedes gelation processes. PEO also facilitates aggregation of growing TiO2 oligomers and particles.