SYNTHESIS AND BULK PROPERTIES OF POLY(TETRAHYDROFURAN)-POLY(2-METHYL-2-OXAZOLINE) ABA TRIBLOCK COPOLYMERS

A series of linear triblock-copolymers of the ABA type in which the ce ntral B-block is poly(tetrahydrofuran) (polyTHF) and the A-segments ar e poly(2-methyl-2-oxazoline) (polyMeOX) were synthesized by a one-pot sequential monomer addition copolymerization, utilizing the living nat ure of the cationic ring-opening polymerization of both monomers. Film s of the copolymers, casted from chloroform solutions, exhibit excelle nt mechanical properties in comparison with the homopolymers with comp arable molecular weights, which was ascribed to the phase separation o ccurring between the two copolymer segments. Materials, in which the p olyTHF B-segment have a molecular weight 13000 g/mol or higher and eac h polyMeOX A-block a molecular weight 1500 g/mol, kept elastomeric pro perties up to 130 degrees C notwithstanding the fact that this tempera ture is considerably higher than the melting point of polyTHF and the glass transition temperature of polyMeOX. It was found that these trib lock-copolymer materials show a shape memory effect. These observation s are attributed to the high degree of phase separation between the tw o blocks and the strong polar interactions between the polyMeOX segmen ts.