Quasi-alternating polyesteramides from ε-caprolactone and α-amino acids

Abstract

Glycine-ɛ-caprolactone-based and α-alanine-ɛ-caprolactone-based polyesteramides with a strong tendency to form alternating sequences (degree of randomness = 1.64 and 1.31) were synthesized by melt polycondensation of intermediate hydroxy- and ethyl ester-terminated amides. These intermediates were synthesized by the reaction of equimolar amounts of ɛ-caprolactone and glycine or L-α-alanine ethyl esters in mild conditions. The structure and microstructure of these polyesteramides are discussed on the basis of an in-depth nuclear magnetic resonance study. Both polyesteramides are semi-crystalline, but the glycine-based one presents the highest melting enthalpy. This polyesteramide also exhibits higher Young's modulus and stress at break than its α- and β-alanine counterparts. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 44220.