INITIATION OF VINYL ETHER POLYMERIZATION BY TRIMETHYLSILYL TRIFLATE, DIMETHYL SULFIDE, AND ADVENTITIOUS WATER

In an effort to use trimethylsilyl trifluoromethanesulfonate (TMSOTf) as an initiator for the living polymerization of isobutyl vinyl ether (IBVE) in the presence of dimethyl sulfide the M(n) versus conversion plot showed a linear relationship for a given solvent. The slope, however, deviated from the calculated one based on an initiator efficiency of 1; i.e., the molecular weights were higher than expected. The addition of water or alcohol increased the initiator efficiency. This result indicated that triflic acid formed by hydrolysis of the TMSOTf was the true initiator. Indeed, in the presence of 2,6-di-tert-butyl-4-methylpyridine (DT-BMP), a proton trap, no polymerization was observed up to 0-degrees-C. Living polymerization occurred, however, with DTBMP in the system when an aldehyde or ketone was added. In these examples, a trimethylsiloxy group was shown to be covalently bound to the polymer by proton NMR. The number-average molecular weight, calculated by assuming there is one trimethylsilyl group per chain, agreed well with that obtained by GPC.