Since polyisocyanates as a class of dynamic helical polymers were discovered in 1959, their distinct conformational and morphological features have become exclusively studied subjects for attractive research fields such as chiroptical switches, macromolecular vehicles, liquid crystals, and photonic crystals. Their macroscopic helical conformation is also similar to structural features of biological macromolecules such as DNA, RNA and proteins. Although many scientists have tried to obtain polyisocyanates with a controlled molecular weight and a narrow weight distribution, the trimerization precluded controlled polyisocyanate formation. To overcome the lack of a living nature, special anionic polymerizations were invented. The use of effective additives and dual functional initiators stabilized the living chain end to prevent the trimerization. These polymerizations eventually achieved the living nature indicating quantitative yield, predictable molecular weight, and a narrow molecular weight distribution. The state of art of anionic polymerization of isocyanates and the effective functionalization techniques led to synthesis of well-defined linear-, telechelic-, chiral-, star-, rod-coil block- and graft polymers. From the controlled molecular architectures, a comprehensive understanding on helical properties and morphologies for polyisocyanates and their block copolymers has been accomplished.

Living anionic polymerization of isocyanates

251st National Meeting (2016)

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