Bis(trifluoromethane)sulfonimide initiated ring-opening polymerization of octamethylcyclotetrasiloxane

Polymerization of octamethylcyclotetrasiloxane in the presence of hexamethyldisiloxane and catalytic amounts of bis(trifluoromethane)sulfonimide (TFSI-H) under dry conditions at 25 or 100 degreesC gave alpha,omega-bis(trimethylsilyl)-polydimethylsiloxanes (PDMS) of a low molecular weight ((M) over bar (n) < 13 000 g mol(-1)). The polymers are very similar to those obtained in the presence of trifluoromethane sulfonic acid as initiator but the polymerization initiated by TFSI-H was faster. Addition of the sufficient quantity of tributylamine to neutralize completely any acid suppressed the polymerization. No polymerization was observed in the presence of triflic anhydride (TfA), trimethylsilyl-bis(trifluoromethane)sulfonimide, trimethylsilyltriflate or the lithium salt of bis(trifluoroniethanesulfonyl)imide. (C) 2002 Elsevier Science B.V. All rights reserved.