Synthesis, Characterization, and Degradation on the Quasi-Alternating Polyester Amides Derived from ε-Caprolactone, Diamine, and Diacid.

Abstract

Poly(ε-caprolactone) (PCL) has been widely studied due to its excellent biodegradability and biocompatibility. However, its low melting temperature (∼60 °C) and limited tensile strength (∼10 MPa) restrict its application in high-performance or thermally demanding environments. To overcome these limitations, we developed a novel two-step melt polycondensation strategy to synthesize quasi-alternating poly(ester amide)s (PEAs) by incorporating diamide diols derived from ε-caprolactone. This synthetic approach enables precise control over the polymer microstructure, leading to PEAs with tunable crystallinity, enhanced chain regularity, and improved segmental interactions. The successful synthesis of PEAs was confirmed using nuclear magnetic resonance and infrared spectroscopy. The results demonstrate that PEAs possess adjustable melting temperatures (T_m = 134-139 °C), moderate crystallinity (X_c = 17-35%), excellent transparency (T > 85%), tensile strength (15-18 MPa), and high elongation at break (ε = 68-800%). This work offers a promising route toward high-performance, sustainable materials for packaging and biomedical applications.