Ring-opening Polymerization Of Octamethylcyclotetrasiloxane Research Articles

Ultrasonically assisted synthesis and degradation of poly(dimethyl siloxane)

The effect of ultrasound on the ring opening polymerization of octamethylcyclotetrasiloxane to give poly(dimethyl siloxane), PDMS, is described. Sonication was found to increase the rate of polymerization over conventional stirring and to give higher molecular weights with lower polydispersities. The results are explained in terms of the efficient mixing and dispersal of acid catalyst given by sonication. The basic effects of sonicating dilute PDMS solutions are also described but it was found that, in contrast to other polymerizations, the degradation plays little part in determining the molecular weight during synthesis.

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 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.