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 °C gave α,ω-bis(trimethylsilyl)-polydimethylsiloxanes (PDMS) of a low molecular weight (<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(trifluoromethanesulfonyl)imide.