Conventional cationic polymerization proceeds only under the strict conditions of low temperature

anhydrous

anaerobic and the protection of high purity inert gas. It is ascribed to the high sensitivity to traces of water of commonly used Lewis acids

and even the presence of a small amount of water can make them invalid. Owing to the concept of "green chemistry" being put forward

water as an environmentally friendly green solvent has been highly appreciated by the industry. In recent years

with the development of water-tolerant initiating systems

cationic polymerization in aqueous media has emerged. It has changed the traditional concept of cationic polymerization

and this new polymerization technique has attracted much attention. This article first introduces the mechanism of cationic polymerization in aqueous media

then emphatically reviews the current research and evolution of cationic polymerization and their matching water-tolerant initiating systems of different monomers in aqueous media

simultaneously points out the advantages and disadvantages of various initiating systems. Finally

the problems existing in cationic polymerization in aqueous media are summed up

in the meantime the research orientations and development outlook are prospected.