H. Kricheldorf
Jan 5, 1979
Citations
0
Influential Citations
12
Citations
Journal
Macromolecular Chemistry and Physics
Abstract
In contrast to 13C NMR spectra, 15N NMR spectra allow one to characterize the sequence of copolypeptides built up by glycyl and β-alanyl residues, because the shifts of the Gly-Gly, β-Ala-Gly, Gly-β-Ala, and β-Ala-β-Ala bonds differ from each other by several p.p.m. Hence, the copolymerization of glycine-NCA and β-Alanine-NCA can be investigated by quantitative evaluation of the 15N NMR spectra obtained from the resulting copolymers. The copolymerization of these two amino acid NCAs initiated by primary amines leads to random sequences; the copolymerization is azeotropic in nature, and both copolymerization reactivity ratio parameters are near 1. If aprotic bases like pyridine and triethylamine are used as catalysts, the rate of incorporation of glycine is higher than that of β-alanine and the copolymers possess a block structure.