LIVING CARBOCATIONIC POLYMERIZATION .48. POLY(ISOBUTYLENE-B-METHYL VINYL ETHER)

The synthesis of poly(isobutylene-b-methyl vinyl ether) (PIB-b-PMeVE) by living carbocationic polymerization (LC+Pzn) employing the sequential monomer addition (SMA) technique is described. The process starts by producing the living PIB+ block employing the 2-chloro-2,4,4-trimethylpentane (TMPCl)/TiCl4 initiating system in the presence of the common ion salt tetra-n-butylammonium chloride (nBu4NCl) in CH3Cl/n-C6H14 or CH2Cl2/n-C6H14 mixed solvents at -80-degrees-C and continues by the addition of methyl vinyl ether (MeVE). The second living block forms only in the presence of excess TiCl4, suggesting that the species that starts the second block and subsequently sustains its growth is a MeVE.TiCl4 complex. The stoichiometry of this complex (1:1 or 1:2) is uncertain. The TiCl4 remains attached to the MeVE units after their incorporation into the diblock; however, it can be readily removed by water. PMeVE obtained in the presence of excess TiCl4 degrades by dealcoholation; however, degradation is prevented by the use of nBu4NCl. Various length (composition) diblocks have been prepared and characterized. The novel PIB-b-PMVEs exhibit strongly amphiphilic character.