Process for the formation of polyhedral oligomeric silsesquioxanes

Abstract

Three methods for preparing polyhedral oligomeric silsesquioxanes (POSS), which utilize the action of a base that can attack silicon atoms or anything that can react with protic solvents (such as ROH, H2O, etc.) and produce hydroxides [ OH]-, alkoxide [RO]- and other compounds. The first method uses these bases to effectively redistribute the silicon-oxygen skeleton structure in the polymerized silsesquioxane [RSiO1.5]∞ to become a POSS nanostructure, that is, the formula [(RSiO1.5)n]∑ Homoleptic fragments represented by #, functionalized homoleptic fragments represented by [(RXSiO1.5)n]∑#, hybrid compounds represented by [(RSiO1.5)m(R'SiO1.5)n]∑# fragments (heteroleptic) and functionalized heterosegment nanostructures represented by {(RSiO1.5)m(RXSiO1.0)n}∑#, where ∞=1-1,000,000 or higher. The second method uses a base to help form POSS nanostructures from the silane RSiX3 and the linear or cyclic silsesquioxane represented by the formula RX2Si-(OSiRX)m-OSiRX2, that is, the formula [(RSiO1.5)n ]∑#, the homogeneous fragments shown and the miscellaneous fragments shown in [(RSiO1.5)m(R'SiO1.5)n]∑# and the heterogeneous fragments shown in [(RSiO1.5)m(RXSiO1.0)n]∑# Functionalized heterosegment nanostructure, where m=0-10, X=OH, Cl, Br, I, alkoxide OR, acetate OOCR, peroxide OOR, amine NR2, isocyanate NCO and R. The third method uses alkali to selectively open the silicon-oxygen-silicon (Si-O-Si) bonds in the POSS structure to form POSS species with incompletely condensed nanostructures. These methods also provide stereochemical control of X. These three methods can generate new POSS species, which can ultimately be transformed into POSS species suitable for polymerization, grafting, or other desired chemical reactions through additional chemical control.

Description

Background of the invention

[0001] The present invention describes methods that enable selective control of the silicon-oxygen backbone structure in polyhedral oligomeric silsesquioxane (POSS) cage molecules. It is desirable to be able to selectively control the framework structure of POSS as they serve as chemical species that can be further converted or incorporated into a wide variety of chemical feedstocks for the preparation of catalyst supports, monomers, polymers, And as a solubilized form of silica to replace fumed and precipitated silica or for biological applications and surface modification. POSS, when incorporated into polymeric materials, can provide new and improved thermal, mechanical and physical properties to common polymeric materials.

[0002] A wide variety of POSS framework structures can be synthesized in useful quantities by hydrolytic condensation of alkyl- or aryl-trichlorosilanes. However, in most cases, hydrolytic condensation reactions of trifunct...