Solvent Effects On Free Radical Polymerization

Free radical polymerization is one of the most useful and lucrative fields of chemistry ever discovered - recent years have seen a tremendous increase in research into this area once considered a mature technological field. Free radical synthetic polymer chemistry is tolerant of diverse functionality and can be performed in a wide range of media. Emulsion and suspension polymerizations have been established as important industrial processes for many years. More recently, the 'green’ synthesis of polymers has diversified from aqueous media to supercritical fluids and the fluorous biphase. Moreover, the last few decades has seen the development of techniques such as nitroxide mediated polymerization (NMP), atom transfer radical polymerization (ATRP), and reversible addition fragmentation chain transfer (RAFT) polymerization, which can allow for intricate control of the polymer molecular weight distribution and chain architecture, as well as considerable progress towards stereocontrolled radical polymerization using Lewis acids, polar solvents and other additives. An enduring feature of the research literature on free radical polymerization has been studies into specific solvent effects. In many cases the influence of solvent is small, however, it is becoming increasingly evident that solvent effects can be used to assist in controlling the polymerization reaction, both at the macroscopic and at the molecular levels. The purpose of this chapter is to give a brief introduction to the types of specific solvent effects that can be achieved in both free radical homo-and copolymerizations.