SYNTHESIS OF A NOVEL OPTICALLY-ACTIVE NYLON-1 POLYMER - ANIONIC-POLYMERIZATION OF L-LEUCINE METHYL-ESTER ISOCYANATE

Synthesis and anionic polymerization of the isocyanate of L-leucine me thyl ester (LeuMI) were carried out. LeuMI was prepared by the reactio n of L-leucine methyl eater hydrochloride with phosgene. Anionic polym erization of LeuMI was carried out at -50 degrees C in dimethylformami de (DMF) using sodium methoxide, potassium tert-butoxide, methyllithiu m, or sodium cyanide under a nitrogen atmosphere. The obtained polymer s were insoluble in common organic solvents such as DMF, tetrahydrofur an, chloroform, and dimethyl sulfoxide, but were soluble in trifluoroa cetic acid. Further, anionic copolymerization of LeuMI with n-butyl is ocyanate (BI) was also carried out to observe that the smaller the con tent of LeuMI unit in the copolymer was, the larger the specific rotat ion of the polymer. From the circular dichroic spectral analyses of th e polymers it was confirmed that the capability of helix formation of poly(LeuMI) was smaller than poly(BI). The relaxation of the helical s tructure of the polymer in trifluoroacetic acid solution was observed, and the smaller the content of LeuMI unit in the copolymer was, the f aster the relaxation of the helical structure. (C) 1995 John Wiley & S ons, Inc.