Synthesis and characterization of new block copolymers with poly(ethylene oxide) and poly [3(S)-sec-butylmorpholine-2,5-dione] sequences

Four different types of polydepsipeptide-polyether block copolymers were synthesized via ring;opening polymerization of 3(S)-sec-butylmorpholine-2,5-dione (BMD) in the presence of hydroxytelechelic poly-(ethylene oxide) (PEO) with stannous octoate as a catalyst. The polymers were an AB block copolymer, an ABA, block copolymer, an (A)(2)B star shaped copolymer and an (A)(2)B(A)(2) copolymer, where A is a poly[3(S)-sec-butyl-morpholine-2,5-dione] (PBMD) and B a poly(ethylene oxide) block. The molar ratio of BMD to PEO was varied to obtain copolymers with different weight fractions of PBMD blocks ranging from 59.8 to 96.7 wt-%. The crystallinity of the PEO phase in the copolymers decreases in the following order: AB > (A)(2)B > ABA > (A)(2)B(A)(2). The static contact angle theta decreases with increasing PEO content in the block copolymers.