The preparation of the mixed alkali metal silanolate K4Li4(OSiMe3)x(OCMe3)8−x (8⩾x⩾5.7) and the effects of mixed alkali metals on the anion induced ring opening polymerization of octamethylcyclotetrasiloxane

Abstract

Abstract The novel mixed alkali metal silanolate K 4 Li 4 ( OSiMe 3 ) x ( OCMe 3 ) 8−x (x=6.8 ( 1 ), 5.7 ( 2 ), 8 ( 3 )) has been prepared via the reaction of hexamethyldisiloxane with n-butyllithium and potassium-butoxide in THF or by the reaction of KOSiMe3 with LiOSiMe3. Molecular weight studies show a partial dissociation to smaller clusters in solution. The mixed alkali metal compounds 1–3, as well as an equimolar mixture of KOSiMe3 and LiOSiMe3, serve as unique catalysts for the anion indueed ring opening polymerization of octamethylcyclotetrasiloxane in that they produce a linear polymer of relatively high molecular weight and low polydispersity.