Synthesis of a new degradable polyurethane elastomer containing polyacetal soft segments

A new polyurethane elastomer with polyacetal soft segments (1) was synthesized by the reaction of hydroxy-terminated telechelic polyacetals (3) with an excess amount of 4,4′-diphenylmethane diisocyanate and by the subsequent chain-extension reaction with 1,4-butanediol. Polyurethane 1 exhibited good mechanical and thermal properties as an elastomer and underwent smooth degradation with a treatment of hydrochloric acid in tetrahydrofuran at room temperature, and 1,4-butanediol and urethane hard-segment residues were produced as degradation products in quantitative yields. These properties of 1 were compared with those of a conventional polyurethane (2) containing poly(tetramethylene ether) glycol (4 or PTMG) as soft segments.