Synthesis and Characterization of Multifunctional Silsesquioxanes and Hybrid Siloxane Materials

Several silsesquioxanes and a hybrid oligosiloxane that were composed of two or more types of siloxane monomers were synthesized, and the extent of synthesis was confirmed through NMR and GPC analysis. These studies represent an effort to create siloxane materials with multiple functionalizations. Issues involving material gelation through polymer crosslinking were addressed through the use of a siloxane end-capping material as well as a reagent to inhibit radical polymer crosslinking. Viscosity studies indicated a positive correlation between the molecular weight of the silsesquioxane and the viscosity of the material. Several sets of reaction conditions were explored including acid and base catalysis, modulation of end-capper levels, and monomer mixing ratios. It was found that acid catalysis was more effective in synthesizing silsesquioxanes with a higher extent of monomer condensation than synthesis under basic conditions. Mass studies performed on an 80/20 n-butyl methacrylate silsesquioxane revealed that the molecular weight of the polymer is inversely related to the end-cap reagent loading. In addition, a set of methyl vinyl silsesquioxanes with different molar ratios of monomers successfully yielded materials that were similar in overall functional group composition to the initial mixing ratios.