Question

Why is cationic polymerization preferred in case of vinyl monomers containing
electron donating group? ​

Answer 1

Formation of active site is the main process in all initialization reactions (including metalorganic Lewis acid action). The process of interaction of vinyl monomers with metalorganic Lewis acid (MLA) consists of several equilibrium stages [1], such as formation of active charged particles and their counter ions and subsequent addition of the charged pair to the monomer. The initial equilibrium is usually slow process while the further attack of the monomer (initialization) is very fast and is comparable with the rate of the reaction of chain growth. Moreover, presence of the cationogenic contaminations in the reaction mixture causes a lot of confusion to chemistry of cationic processes. Now we can consider more or less confidently only two possible ways of initialization of polymerization of vinyl monomers by MLA: direct initialization and co-initialization