Crystallization of polypeptides in the course of polymerization, 2. Chain folded crystals of polyglycine and poly‐β‐alanine

Abstract

Abstract The polymerization of N ‐carboxy anhydrides of glycine and β‐alanine was studied in acetonitrile with butylamine as initiator. As was expected from the similarity of the backbone chain structure to nylons, the polymer precipitated in the form of a spherulite consisting of ribbon like crystalline units just as in the case of nylons previously reported. The molecules in the ribbon like crystals were arranged antiparallel forming a hydrogenbonded sheet. The result contrasts with that reported previously on some α‐amino acids which gave helical polymer molecules organized in the form of an extended chain crystal. The mechanism of the crystal growth has been discussed along the same line as in the case of nylons.