Microwave-assisted synthesis of glycopolymers by ring-opening metathesis polymerization (ROMP) in an emulsion system

The protecting-group-free synthesis of versatile glycopolymers accelerated by microwave irradiation in an emulsion system is presented herein. Copper-catalyzed azide-alkyne cycloaddition (CuAAC) was employed to prepare a wide range of glycosylated hydrophilic monomers, and a series of glycopolymers were fabricated via ring-opening metathesis polymerization (ROMP). Our data revealed that phase transfer catalysis (PTC) in an emulsion system was more superior to that of homogeneous solvents (organic and aqueous solvents). Grubbs 2nd, Grubbs 3rd, and Hoveyda-Grubbs 2nd (H-G 2nd) catalysts were systematically screened from room temperature to 75 degrees C, of which the H-G 2nd catalyst exhibited more compatibility with microwave irradiation in emulsion polymerization. The efficiency of polymerization was significantly enhanced under microwave irradiation that was completed in less than 5 min for homopolymerization and within 15 min for multi-block polymerization. Six glycopolymers were successfully synthesized under optimum conditions. In addition, the surface plasmon resonance (SPR) analysis indicated that the mannose-functionalized multi-block glycopolymers (p-Glu-b-Man and p-Glu-b-Man-b-Fuc) exhibited dramatic improvements in their binding affinities to concanavalin A (ConA) as compared to the homoglycopolymer (p-Man). The robust approach developed in this study offers the efficient fabrication of versatile glycopolymers for potential biological and medical applications.