Well-Defined Selenium-Containing Aliphatic Polycarbonates via Lipase-Catalyzed Ring-Opening Polymerization of Selenic Macrocyclic Carbonate Monomer

The synthesis of well-defined, biodegradable selenium-containing polymers remains a formidable challenge in polymer chemistry. Herein, a selenic cyclic carbonate dimer monomer (M-se) was developed to generate well-defined, biodegradable aliphatic polycarbonates with selenide functionality on the backbone. The monomer was synthesized via the intermolecular cyclization of di(1-hydroxyethylene) selenide and diphenyl carbonate with lipase CA as catalysts in a mass of anhydrous toluene with very dilute monomer concentration. Then living ring-opening polymerization (ROP) was executed by solution method using the same lipase CA as catalysts. Similarly, the copolymerizations with commercial trimethylene carbonate (TMC) generated random copolymers demonstrated by C-13 NMR, regulating the density of selenium functional groups. The resulting polymers exhibited a living polymerization characteristic, as evidenced by polymerization kinetics, predictable molecular weights, narrow molecular-weight distribution, and controlled copolymer compositions. Using hydrophilic macroinitiators (PEG), amphiphilic di/triblock copolymers could be obtained, suggesting their potential as controlled drug delivery system (DDS) and hydrogel scaffolds for tissue engineering.