Polymer synthesis by phase-transfer catalysis

The polymer synthesis by phase-transfer catalysis (PTC) is reviewed. The applications of quaternary ammonium salt and crown ether as phase-transfer catalysts for the nucleophilic substitution, anionic ring-opening polymerization, and free radical polymerization are introduced. Emphasis is placed on some nucleophilic substitution reactions for the chemical modification and functionalization of polystyrene, including synthesis route, reaction mechanism, and factors such as temperature, types and contents of the catalysts and solvents. Crown ether is little better than quaternary ammonium salt in most PTC reactions, but the latter is much cheaper and less poisonous. We believe that future research should put emphasis on the reactions catalyzed by quaternary ammonium salt, so that the PTC technology could be industrialized as soon as possible.