| 초록 |
Polyisocyanates have drawn great attention because of their helical conformation. Accordingly, the synthesis of living polyisocyanates has been a primary requirement for research. Advances in anionic polymerization have opened a way to yield polyisocyanates having a precisely controlled MW and narrow MWD. One noteworthy discovery of the polymerization is the “cross-association” which indicates the direct addition of an n-meric associate of initiator ((RNa)n) to a monomer (M), forming a mixed-aggregate composed of a propagating ion pair and n-1 initiator molecules (RMNa(RNa)n-1). This mechanism is indeed advantageous, because this performs the dual function of initiating the polymerization and simultaneously protecting the unstable chain end from the backbiting side reaction. Several associated initiators have exhibited the living polymerization behaviors and characteristic initiation efficiencies. Surprisingly, the initiation efficiencies have changed in the presence of additives. |
