Synthesis of hyperbranched polyether: anionic ring-opening polymerization of 3-ethyl-3-(hydroxymethyl)oxetane using potassium tert-butoxide as an initiator

摘要

Oxiranes with 3-membered ring were polymerized cationically and anionically to produce the polyethers with high molecular weights in high yields. Cationic polymerization of oxiranes is often accompanied with the chain transfer reaction of oxygen moieties of the polymer main chain due to the low basicity of oxiranes. In contrast, anionic polymerization of oxiranes is not formed the cyclic oligomers. Coordinate polymerization of oxiranes affords the stereoregular polymers with high molecular weight in high yield. Meanwhile, oxetanes with 4-membered ring, are well known to be polymerized exclusively with cationic initiator, due to their highly basicity. Vandenberg et al. reported that cationic ring-opening polymerization of 3-ethyl-3-(hydroxymethyl)-oxetane (EHO) in the presence of aluminum complexes as cationic initiators produced linear polymers with highly crystallinity and no glass transition temperature. Furthermore, Hult and Johansson et al. reported the hyperbranched polymers by the cationic ring-opening polymerization of EHO using sulfonium salts as cationic initiators. Inoue et al. performed the living anionic polymerization of oxetanes using aluminum porphyrin/Lewis acid as a catalyst. Meanwhile, our research groups have been developed the useful reactions of oxetanes for synthetic organic chemistry and polymer synthesis. However, no research has been reported concerning the anionic polymerization of oxetanes using common anionic initiators such as butyllithium (BuLi), sodium metoxide (MeONa), potassium tert-butoxide (t-BuOK) and etc. Herein, we describe successful results of anionic ring-opening polymerization of oxetane, 3-ethyl(3hydroxymethyl)oxetane (EHO).