Characterization of 1:1 Random Copolymers Obtained from 6-, 7-, 11-, and 12-Carbon Amino Acids

摘要

Copolymers were prepared from the title amino acids by melt condensation underdry nitrogen. The resulting copolymers were characterized by solution and solid-state NMR, FTIR, DSC, and WAXD. Solution NMR spectra (at 75.5 MHz) showed multiple peaks with almost equal intensities in the carbonyl region (indicating random copolymer formation) with no evidence of end-group peaks (confirming high molecular weight). Solid-state 13C (at 100.6 MHz) and 15 N (at 20.3 MHz) spectra of most solution cast films contained peaks consistent with the gamma-form crystallites (sigma Nl5 ca 89) being the predominant ordered phase. Only nylon 6-co-7 formed almost exclusive alpha-form on solution casting (sigma Nl5 84.5). Nylon 7-co-11 formed the alpha-form almost exclusively from the melt but gave a