| The discovery that the hydrosilation of di- and multifunctional Si-H compounds with olefins takes place in a discrete, stepwise fashion has led to the development of novel synthetic methods for the preparation of ambifunctional monomers bearing differentiated functionality at both ends of the molecule. A key factor in the discovery was the observation that the catalyst, RhCl({dollar}rm Phsb3P)sb3{dollar}, effectively suppresses the competing epoxide ring-opening polymerization while permitting the formation of a high proportion of monohydrosilation to dihydrosilation. This has led to the preparation of {dollar}alpha{dollar}-hydrogen-{dollar}omega{dollar}-functional silane and siloxane compounds in high yield which cannot only serve as interesting monomers in their own right but also as intermediates for the introduction of other functional groups by subsequent hydrosilation reactions. Application of this chemistry has resulted in the preparation of interesting and novel classes of well characterized ambifunctional monomers and oligomers. These monomers can be polymerized using additional cationic initiators such as onium salt photoinitiators. |
