| 초록 |
Since polyisocyanates as a class of dynamic helical polymers were synthesized by anionic polymerization in 1959, they have become extensively studied materials for chiroptical switches, macromolecular vehicles, liquid crystals, and photonic crystals. Although several cases on anionic polymerization of isocyanates using aggregative initiators have been reported in the last 10 years, the exact polymerization mechanism has still been unfound. Herein, we report a kinetic study on the anionic polymerization of n-hexyl isocyanate using a model initiator, sodium diphenylamide (NaDPA), which is known to aggregate into a solvated dimer in THF. To prevent the unnecessary side reaction (termination and/or trimerization), sodium tetraphenylborate (NaBPh4) was added. The results showed the propagation rate is proportional to half-order in the concentration of propagating anion and the initiation efficiency of NaDPA is ~50%, indicating the dimeric aggregate participates in the propagation reaction. |
