US Patent 6927270 Process for the functionalization of polyhedral oligomeric silsesquioxanes

Efficient processes have been developed for the cost effective functionalization of polyhedral oligomeric silsesquioxane-silanols (POSS-Silanols) and for the manufacture of polyfunctional polyhedral oligomeric silsesquioxanes. The processes utilize the action of bases or acids on silane coupling agents. The preferred process utilizes base to promote the silylation of POSS-Silanols of the formula [(RSiO1.5)n(R(HO)SiO1.0)m]Σ# with silane coupling agents to form POSS species with functionalized incompletely condensed nanostructures [(RSiO1.5)n(R(YSiR2O)SiO1.0)m]Σ# or functionalized completely condensed nanostructures [(RSiO1.5)n(YSiO1.5)1]Σ#. The process can alternately be conducted with acids. A second process utilizes base to alkylate POSS-Silanols with functionalized alkyl halides. A third related process utilizes base to react with silane coupling agents to form polyfunctional, fully condensed POSS species of formula [(YSiO1.5)n]Σ#. This process can also alternately be conducted under acidic conditions. Each of the processes result in new POSS compositions that can undergo additional desirable chemical reactions or which are directly suitable for polymerization or grafting into polymeric materials. POSS frameworks containing silanol and other reactive functionalities suitable for polymerizations have previously been described as valuable co-monomers in polymerizations and as feed-stocks for the preparation of a diverse number of chemical agents that are useful in polymeric materials in biological applications, and for the modification of surfaces.