Alternating Ring-Opening Metathesis Copolymerization of Amino Acid Derived Norbornene Monomers Carrying Nonprotected Carboxy and Amino Groups Based on Acid-Base Interaction

摘要

Amino acid derived norbornene monomers having carboxy (1) and amino groups (2) were synthesized and subjected to ring-opening metathesis copolymerization with various feed ratios using the Grubbs second generation ruthenium catalyst. The M_n's of the copolymers ranged from 5300 to 9400 (M~w/M_n = 1.40-1.69). The monomer conversion and M_n of the copolymer were maximized when the monomer feed ratio was 1:1. The monomer unit ratios in the copolymers were almost 1:1 at 10% conversion, irrespective of the feed ratios. The monomer reactivity ratios r_1 and r_2 were estimated to be 0.08 and 0.02, which confirmed that alternating copolymerization occurred. It is considered that alternating copolymerization is brought about by the acid-base interaction between the monomers and/or between the propagating polymer end and the incoming monomer.