Microgel Star Polymer Catalysts as Active and Functional Nanoreactors for Organic Reactions and Polymerizations

Abstract

In this chapter, we present recent advances on microgel star polymer catalysts as active and functional nanoreactors for organic reactions and polymerizations. Microgel star polymers are soluble core-shell gels consisting of a covalently crosslinked microgel core that is covered by multiple linear arm chains. The central cores thus serve as nano-confined spaces for various applications. Actually, microgel star polymers are effective as polymeric scaffolds to immobilize metal catalysts and organocatalysts since the catalysts are not only dissolved in a homogeneous phase but also effectively protected within the crosslinked network and isolated with arm chains from outer environments. A series of functional microgel star polymer catalysts are efficiently synthesized by the linking reaction of linear polymers with functional linking agents and monomers in living radical polymerization. Metal-bearing microgel star polymer catalysts have high activity, functionality tolerance, recyclability, and provide easy product recovery in sec-alcohol oxidation, ketone hydrogenation, and living radical polymerization; the compatibility of catalytic activity and practicability is much better than those of conventional heterogeneous supported catalysts and homogeneous nonsupported counterparts. Because of their inherent structure, star polymer catalysts further afford unique thermoregulated phase-transfer catalysis and one-pot cascade reactionsCascade reaction(s). Thus, microgel star polymers are one of the most advanced polymer supports with nano-confined designer spaces for catalysis.