Rapid, Metal-Free Room Temperature Vulcanization Produces Silicone Elastomers

Silicone room temperature vulcanization elastomers are usually formed through either a platinum-catalyzed hydrosilylation or tin-catalyzed moisture cure. In this article, we show that it is possible to create robust, transparent silicone elastomers without the need for metal catalysts. Hydrogen-terminated silicone polymers are crosslinked by tri- or tetraalkox-ysilane crosslinkers in a condensation process catalyzed by the presence of trispentafluorophenylborane catalyst to give elastomers and alkane by-products. This procedure allows for very fast cure times (< 30 s to a tack free state): the process is more conveniently controlled with the addition of a small amount of solvent. Physical and mechanical properties are readily modified by control of the chain length of the starting polymer, the functionality and nature of the alkoxy group on the crosslinker. Organofunctional groups, useful for further polymer modification, can optionally be incorporated by judicious choice of readily available starting materials. (C) 2012 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013, 51, 644-652