Abstract: With the increasing global awareness of environmental protection, growing attention to sustainability issues, and the reality of dwindling fossil resources, the environmental pollution caused by traditional fossil-based plastics has gradually become a focal point in society. These challenges drive efforts to actively explore and develop new eco-friendly materials. In this context, the research and application of biopolymers have gained widespread attention. Biopolymers, due to their unique advantages such as being derived from renewable resources, being biodegradable, and being biocompatible, have become an ideal solution to address environmental pollution and resource depletion. In particular, polylactic acid (PLA), as a key bio-based material, has gradually become a popular alternative to traditional plastics due to its excellent biocompatibility, biodegradability, and the fact that it is made from plant starch. As a result, PLA has broad prospects in the fields of environmental protection and sustainable development, attracting increasing attention from both scholars and industry. However, PLA has some drawbacks, such as poor ductility and slow degradation rate, which limit its widespread application in industrial fields.
To promote the degradation of polylactic acid (PLA) and improve its ductility, so as to expand its applications in industry and daily life, this study prepared composite materials of poly(lactic-co-glycolic acid) (PLGA)/PLLA using an open-loop copolymerization method. Curcumin was introduced into the system through electrospinning and solution blending to regulate the degradation behavior and mechanical properties of the composite materials. The structure and molecular weight distribution of the copolymer products were analyzed using nuclear magnetic resonance (NMR) spectroscopy and gel permeation chromatography (GPC). The effects of PLLA's optical purity and the sequence distribution of glycolic acid (GA) in PLGA on the phase morphology, crystallinity, thermal stability, mechanical properties, degradation behavior, and drug release behavior of the composite materials were explored using such methods as differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), and tensile testing. The study showed that by controlling the optical purity of PLLA and the ratio of L-lactide (L-LA) to GA in PLGA, the mechanical properties and degradation rate of the PLLA/PLGA blends could be effectively adjusted. When the optical purity of PLLA was 88%, and the L-LA to GA feed ratio in PLGA was 7:3, the composite material exhibited excellent ductility and degradation rate, with a breaking elongation of over 400% and a mass loss of 86% after six days of enzymatic degradation. Moreover, the drug release performance of the PLLA/PLGA drug-loaded composite membrane was closely related to its degradation behavior, with sustained release for up to one week.
In summary, PLLA/PLGA composite films demonstrate certain application value in the field of controllable degradation and sustained release materials. This study not only provides experimental evidence for optimizing the degradation behavior of PLA materials, but also offers feasible strategies for improving their ductility.

Key words: polylactic acid, poly(L-Lactide-co-glycolide)??, controllable degradation, electrospinning, drug release, solution blending

摘要： 为提高聚左旋乳酸（PLLA）的延展性并促进其水解降解，将L-丙交酯（L-LA）与乙交酯（GA）通过开环共聚的方法制备出聚乙丙交酯（PLGA），再将PLGA与PLLA溶液共混制备成PLLA/PLGA共混物，并用溶液共混和静电纺丝法制备了载有姜黄素的PLLA/PLGA复合膜，并研究了PLLA/PLGA共混物的热稳定性、结晶性、力学性能、降解行为及其复合膜的药物释放特性。结果表明：PLGA的加入显著改善了PLLA的延展性和降解速率；经过7 d酶降解后，PLLA/PLGA共混物（7∶3）的质量损失率为24.5%，几乎是纯PLLA的7倍；当PLLA光学纯度从98.5%降至88%时，PLLA/PLGA共混物的断裂伸长率从157%增至400%以上；PLLA/PLGA复合膜的药物释放速率与其降解规律一致，可持续释放168 h。研究结果可为PLLA在可控降解材料领域的应用提供参考。

关键词: 聚乳酸, 聚乙丙交酯, 可控降解, 静电纺丝, 药物释放, 溶液共混