HIGHLY RADICAL-POLYMERIZABLE METHACRYLAMIDE HAVING DIPEPTIDE STRUCTURE - SYNTHESIS AND RADICAL POLYMERIZATION OF N-METHACRYLOYL-L-LEUCYL-L-ALANINE METHYL-ESTER

Synthesis and radical polymerization of methacrylamide having an L-leu cyl-L-alanine methyl ester structure, N-methacryloyl-L-leucyl-L-alanin e methyl ester (MA-LA-M), were carried out. Radical polymerization of MA-LA-M in the presence of AIBN (1 mol %) in chlorobenzene (1.0 mol/L) afforded the corresponding polymer (poly(MA-LA-M)) with M(n) 196 000. The 10% weight loss temperature of poly(MA-LA-M) under nitrogen was 3 00 degrees C. Increase of the absolute value of specific rotation in t he transformation from MA-LA-M (-48.0 degrees) to poly(MA-LA-M) (-76.5 degrees) could be observed. The rate of radical polymerization of MA- LA-M was 4-6 times larger than that of N-methacryloyl-L-leucine methyl ester (MA-L-M) in benzene-d(6) (1.0 mol/L), whereas the activation en ergy (E(a)) of MA-LA-M (51.4 kJ/mol) was larger than that of MA-L-M (2 9.7 kJ/mol). The absolute value of the activation entropy (Delta S-dou ble dagger) in the radical polymerization of MA-LA-M (-144 J/(K . mol) ) was smaller than that of MA-L-M (-221 J/(K . mol)). These parameters for the both monomers were nearly equal in the polymerizations in DMS O-d(6). From the IR and H-1 NMR analyses, MA-LA-M in benzene might be suggested to be more strongly aggregated each other by intermolecular hydrogen bonds than MA-L-M.