The synthesis of well-defined living polymers of isobutyl vinyl ether (IBVE) has been accomplished with trifluoromethanesulfonic (triflic) acid or Lewis acids plus proton sources as initiators. Excess alkyl sulfides were used to stabilize the carbocationic chain ends. The number-average molecular weight (Mn) of the polymers obtained was directly proportional to monomer conversion. The molecular weight distribution (MWD) was narrow.As the sulfide concentration was increased, the rate of polymerization decreased and a nearly monodisperse polymer was obtained. With triflic acid initiator living conditions were observed at -40 and -15 °C. With EtAlCl2 initiator the living polymer is obtained even at 0 °C. When the bulkiness of the sulfide was increased, the rate of polymerization increased but the system deviated from living behavior. Mechanistic studies indicate that alkyl sulfides reduce the concentration of active propagating species via reversible sulfonium ion formation.

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" 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 °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.

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SynopsisGraft polyniers of acrylonitrile, neth ha cry lo nit rile and methyl methacrylate on polyhydroxy polymers such as cellulose and polyvinyl alcohol were prepared by anionic graft polymerization. The alkali alkoxide derivative of the polyhydroxy polymer backbone was used as initiator of polymerization. The graft polymerizations were carried out in liquid ammonia and other inert solvents a t low temperature. Grafting was accompanied by considerable homopolymerization caused by chain transfer to monomer and to ammonia. The graft polymers were separated from homopolymers and unreacted polyhydroxy polymers by extraction with suitable solvents. The per cent of the grafted vinyl polymer increased with increase in the monomer and alkoxide concentrations. No crosslinking occurred during the anionic graft polymerization, and soluble graft polymers were obtained.