An Industrial History ofRAFTPolymerization

This chapter traces the history of radical polymerization with reversible addition–fragmentation chain transfer (RAFT polymerization) and the rapid evolution in applications of that technique through reference to the patent literature. We cover the origins of the method, which lie with the development of the so-called macromonomer RAFT agents. Macromonomer RAFT polymerization, also now known as sulphur-free RAFT polymerization, drew significant interest from the industry, particularly with commercial development of low VOC coatings and effective dispersants for pigments and dyes. However, the term RAFT agent can usually be understood to refer to thiocarbonylthio RAFT agents, which are most often dithioesters, trithiocarbonates, xanthates, or dithiocarbamates. Patents on thiocarbonylthio RAFT polymerization continue to increase. There are currently almost 150 new patent families appearing each year. We describe the patents that may be pivotal to the development of thiocarbonylthio RAFT polymerization as a technique paying particular attention to RAFT emulsion polymerization and the use of RAFT for the synthesis of stars, including nano- or microgels. We then consider the wide range of RAFT applications, which include bioapplications (therapeutic, cosmetic, and ophthalmic), electronic applications (resists and polymer semiconductors), and industrial applications (dispersants, coatings, and adhesives) that are responsible for most of the patent literature in the field.