Dual-Temperature-Responsive Microgels from a Zwitterionic Functional Graft Copolymer with Superior Protein Repelling Property

Abstract

In this work, we developed a synthetic strategy to synthesize dual-temperature-responsive low surface fouling zwitterionic microgels. Statistical poly(<i>N</i>-vinylcaprolactam-<i>co</i>-glycidyl methacrylate) copolymers were synthesized by RAFT polymerization and post-modified by thiol-epoxy click reaction with thiol end-group-modified poly(sulfobetaine) macro-RAFT (PSB-SH) to obtain poly(<i>N</i>-vinylcaprolactam-<i>co</i>-glycidyl methacrylate)-<i>graft</i>-poly(sulfobetaine) (PVCL-<i>co</i>-PGMA-<i>g</i>-PSB) graft copolymers. Synthesized graft copolymers were cross-linked by diamine cross-linker in water-in-oil (w/o) inverse mini-emulsion to obtain zwitterionic microgels. Using this approach, we synthesized microgels with unique microstructure, high loading and uniform distribution of poly(sulfobetaine) chains, which exhibits tunable dual-volume phase transition temperatures. The microgels also showed excellent antifouling property reflected in strongly reduced protein absorption on a microgel-coated surface observed in real time by a Quartz Crystal Microbalance with Dissipation (QCM-D) monitoring experiment with continuous flow of protein solution. Therefore, this kind of zwitterionic microgel can be potentially used for temperature-triggered drug delivery and anti-bioadhesion coating material as well.