SILOXANE COUPLING AGENTS

New siloxane coupling agents have been prepared by the platinum-cataly zed addition of C-H2=CHSi(OR)(3) silanes (R = CH3 or CH2CH2OCH3) to fo ur different siloxanes, oly[(methylhydrogen)siloxane-co-dimethylsiloxa ne], poly[(methylhydrogen)siloxane] (dp = 33), tetramethyldisiloxane, and tetramethylcyclotetrasiloxane. These new hydrophobic materials off er a distinct alternative to conventional silane coupling agents, prev alent in many industrial applications. The new preparations allow for control of molecular weight, the extent of coupling functionality, and the distribution of coupling groups on the siloxane backbone. The use of 2D NMR experiments, COSY, and HETCOR indicated two modes of additi on to the Si-H groups had occurred, Markovnikov and anti-Markovnikov. GPC, FTIR, and H-1 and C-13 NMR were used to thoroughly characterize a ll the reaction products.