Construction of Fully Biodegradable Poly(L‐Lactide‐Co‐Caprolactone) Random Copolymer/Poly(D‐Lactide) Blend: Crystallization, Toughness, and Biodegradability

ABSTRACT In this work, poly(L‐lactide‐co‐ε‐caprolactone) (PLCL) copolymers with varying ε‐caprolactone (ε‐CL) contents that ranged from 0% to 10% were synthesized via ring‐opening polymerization of L‐lactide and ε‐CL at 170°C for 1 h. Fully biodegradable PLCL/poly(D‐lactide) (PDLA) blends with stereocomplex (SC) crystallites were fabricated through a solution blending approach. The effects of ε‐CL content in PLCL on the crystallization behavior, thermal properties, mechanical performance, and degradation behavior of PLCL/PDLA blends were systematically investigated. The successful synthesis of PLCL was confirmed by 1 H NMR and FTIR analyses. The melting peaks observed in the high‐temperature region and the characteristic diffractions in WAXD patterns provided evidence for the formation of SC crystallites in PLCL/PDLA blends. Compared with PLCL, the incorporation of PDLA significantly enhanced the crystallization rate, due to the nucleation function of SC crystallites. With increasing ε‐CL content in the copolymer system, the T g and crystallinity of PLCL gradually reduced, and the melting peaks of HC and SC crystals shifted toward lower temperatures due to the reduced sequence regularity. A pronounced improvement in deformability was achieved by the presence of ε‐CL segments. As the ε‐CL content increased from 1.5% to 10%, the elongation at break rose from 12% to 192%, with the morphology of elongated fibrils. Higher ε‐CL contents accelerated enzymatic degradation, with mass loss exceeding 75% after 7 days at 10% ε‐CL, because the increased chain mobility may facilitate the penetration of water and Proteinase K into the blend, thereby promoting enzymatic erosion. Overall, high‐performance PLA‐based composites with excellent biodegradability were achieved via SC crystallization and modulation of ε‐CL comonomer content.