Isomeric Silicones: Reactive Phenylsilsesquioxane-Based MT Resins and Comments Concerning the Structure of the Phenylsilsesquioxane Homopolymer

Condensation products of trimethylsilanol and phenylsilanetriol (MTϕ oligomers and polymers) were prepared by both base- and acid-catalyzed hydrolysis and co-condensation of phenyltrimethoxysilane (T monomer) and hexamethyldisiloxane (M dimer). The composition and molecular weight of the products were controlled by varying the M/T feed ratio and reaction conditions, particularly the solvent identity. Vinyldimethyl-M (MV) and hydridodimethyl-M (MH) derivatives were prepared analogously for use as resins to form monolithic transparent solids using platinum-catalyzed hydrosilylation. Comments concerning the structure of the homopolymer, poly(phenylsilsesquioxane), pTϕ, are made with reference to the structures of the isomeric oligomers reported as well as literature descriptions of the structure of this polymer.