Crystallization of glycine/β-benzyl-L-aspartate copolymer in the course of polymerization

In order to examine the structure and growth mechanism of copolymer crystals formed during polymerization, the heterogeneous copolymerization of glycine N-carboxy anhydride and β-benzyl-L-aspartate N-carboxy anhydride, initiated by butylamine, was studied in acetonitrile. In all the copolymerization systems, the crystal growth took place through formation of the cross-β structure, i.e., the introduction of glycine residues into the poly(β-benzyl-L-aspartate) chain during this particular copolymerization broke the α-helix of poly(β-benzyl-L-aspartate). The growth mechanism of the copolymer crystals was compared with that for poly(β-benzyl-L-aspartate) crystals reported previously.