Aromatic Acetals as New Initiators for Cationic Polymerization of Isobutyl Vinyl Ether

Abstract

A series of aromatic acetals (1) from substituted phenols [CH3CH(OiBu)OAr; Ar = C6H5, p-CH3OC(O)C6H4, p-CH3C(O)C6H4, p-NO2C6H4, 4-NO2-2,6-di-C6H5−C6H2, o-CH3C(O)C6H4] were employed as new initiators in conjunction with Lewis acids (MtXn) for the living cationic polymerization of isobutyl vinyl ether (IBVE). Most of them were quantitatively synthesized by the addition of the corresponding phenols to IBVE. When coupled with aluminum chloride (AlCl3), 1 gave polymers with broad molecular weight distributions (MWDs), whereas the addition of ethyl acetate (10 vol %) to these systems led to the formation of controlled polymers whose number-average molecular weights (Mn) were directly proportional to monomer conversion, with relatively narrow distributions (Mw/Mn ∼ 1.2). The aromatic acetals in conjunction with tin halides (SnX4; X = Cl, Br) gave relatively high meso contents (81%) in toluene at −78 °C.