Degradable terpolyesters synthesized from a monomer mixture mediated by a heterometallic complex: Defined monomer- and stereo-sequences

Abstract

Copolymers provide a feasible platform to extend the structures of polymeric material, and the control of architecture (such as monomer sequence and stereo sequence) plays a critical role in tailoring specific properties. Herein, a heterometallic (Salph Zn)2-Ho complex was screened out for the synthesis of architecture-defined block terpolymers from a monomer mixture of epoxide, cyclic anhydride and l-lactide (LLA). The polymerization in one-pot firstly underwent ring-opening copolymerization reaction producing completely alternating ester linkage, and then transformed to LLA polymerization with trace stereoerrors, forming block polyesters with a semicrystalline segment and an amorphous segment. The polymerization was “immortal” with the ability to synthesize sequence-defined multiblock polyesters by sequential monomer addition. Furthermore, DSC traces revealed that the obtained block polyesters exhibited distinct thermal properties stemming from each segment. The melting temperature of block terpolymer was increased to 207.6 °C facilitated by the stereocomplexes of PLA segment.