Cationic polymerization prospects

Many prospective photoinitiators fail to meet the basic requirements outlined above. Thus, for example, trialkylsulfonium salts are not useful photoinitiators because they do not absorb light in the ultraviolet and because as alkylating agents, they spontaneously initiate cationic polymerization even in the absence of light... 

A number of synthetic methods have been successfully developed for the synthesis of block copolymers. They include polycondensation, anionic, cationic, coordinative and free-radical polymerizations and also mechano-chemical synthesis. Despite the exceptional amount of attention paid to the prospects of various catalytic systems, radical polymerization has not lost any of its importance, particularly in this area. Its competitiveness with other methods of conducting polymerization are attributable to the simplicity of the mechanism and good reproducibility. Actually, the extensive use of free radical polymerization in practice is well understood when considering the ease of the process, the soft processable conditions of vacuum and temperature, the fact that reactants do not need to be highly pure and the absence of residual catalyst in the final product. Thus, it can be easily understood that more than 50% of all plastics have been produced industrially via radical polymerization. 

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