Living anionic polymerization of isocyanate containing a reactive carbamate group

Abstract

Anionic polymerization of n-alkoxycarbonylaminohexyl isocyanates was carried out using a sodium benzanilide (Na-B A) as an initiator without additives in tetrahydrofuran (THF) at - 98 °C under high vacuum (10 -6 Torr). The polymerization of methoxycarbonylaminohexyl isocyanate (MAHI) resulted in an insoluble material. However, the polymerization of n-propyloxycarbonylaminohexyl isocyanate (PAHI) with propyl side chain was moderately controlled and gave high yields (∼98%) of the polymers with polydispersity index (PDI 1.18-1.22). The results of the polymerization were improved significantly when n-pentanoxycarbonylaminohexyl isocyanate (PEAHI) with pentyl side chain was used. Poly(n-pentanox-ycarbonylaminohexyl isocyanate) (PPEAHI) was isolated in ∼99% yields, controlled molecular weight, and a narrow PDI (1.08-1.14). The living nature of PPEAHI was indicated from the linear plot of the molar ratio of the monomer to the initiator versus the number-average molecular weight (M n) in addition to the successful block copolymerization of PEAHI with another isocyanate monomer, n-hexyl isocyanate (HIC). Furthermore, the hydrogen bonding between the active hydrogen of the carbamate group of the PPEAHI and the nitrogen atom of the poly(2-vinylpyridine) formed a vesicle-like morphology in methanol. © 2009 American Chemical Society.