Hydrosilylation Polymerisation

Abstract

The catalytic hydrosilylation of difunctional organosilicon monomers containing alkenyl-or alkynyl-groups and/or Si-H bonds has become a versatile synthetic tool for obtaining saturated or unsaturated organosilicon polymers bearing the Si-C bonds in the backbone. These important polymeric products have been prepared through two main routes: the intermolecular hydrosilylation polymeri-sation of alkenyl(alkynyl)hydrosilanes and the polyhydrosilylation of α,ω-dienes or diynes with dihydro-substituted organosilicon compounds. The chapter covers recent achievements on the synthesis of saturated polycarbosilanes and polycar-bosiloxanes as well as unsaturated polycarbosilanes or related σ-π conjugated polymers using transition metal catalysed hydrosilylation polymerisation. The catalytic hydrosilylation of difunctional organosilicon monomers containing alkenyl groups and/or Si-H bonds leads to formation of saturated organosilicon polymers. These polymeric products, depending on their structure or the degree of branching-have recently been applied as precursors of ceramic materials char-acterised by truly unparalleled resistance to chemical and mechanical factors. Recently , polycarbosilanes and related polymers have also attracted increasing attention for their applicability in heat-resistant materials (coatings, paints or prepergs) and moulding materials [1]. On the other hand, hydrosilylation of difunctional organosilicon monomers containing alkynyl groups and/or Si-H bonds leads to formation of unsaturated polycarbosilanes or related σ-π conjugated polymers. These polymeric products, also known as poly(silylenevinylene)s or poly(arylene-silylene-vinylene)s (where monomers with aromatic functionalities are polymerised) have gained increasing attention for their potential applications to optoelectronic devices, heat-resistant materials and ceramic materials. Such silicon-containing σ-π conjugated polymers are expected to be photoresistant and photo-and electroluminescent materials featuring high processability, because they are more flexible and soluble than classical conjugated organic polymers without silicon. Hydrosilylation polymerisation leading to polycarbosilanes (polycarbosiloxanes) may be carried out by means of the following processes: B.