School of Materials Science and Engineering, Zhejiang Sci-Tech University, Hangzhou, 310018, China; Zhejiang Provincial Innovation Center of Advanced Textile Technology, Shaoxing, 312000, China.
School of Materials Science and Engineering, Zhejiang Sci-Tech University, Hangzhou, 310018, China.
Int J Biol Macromol. 2024 Oct;277(Pt 1):134159. doi: 10.1016/j.ijbiomac.2024.134159. Epub 2024 Jul 24.
The development of high-performance biodegradable polylactic acid (PLA) materials integrating high strength, malleability and toughness is desired but an ongoing challenge. In this work, a novel full-biobased block copolymer was designed and synthesized by grafting L (+)-lactide (L-LA) and ε-caprolactone (ε-CL) onto lignin via ring-opening polymerization. The obtained lignin-PLA-PCL block copolymer was composed of rigid lignin and poly (LA-CL) rubber segment, could self-assemble into uniform nano-micelles with average diameters of 80-100 nm regulated by simply altering copolymer content. The incorporation of lignin-PLA-PCL copolymers into PLA matrix induced the formation of many cavities, promoted free volume between PLA matrix and copolymer to accelerate chain mobility, achieving excellent ductility and stretchability with maximum stretching deformation of 64.8 %. The resultant PLA composites with the copolymer content as low as 5 wt% displayed simultaneously improved strength (41.84 MPa) and toughness (8.1 MJ/m), 6.7 % and 1520 % increment than those of neat PLA, respectively. The reinforcing and toughening mechanisms were explored and verified that the combination of cavity growth and fibrillation, followed by extensive shear yielding of matrix, causing substantial plastic deformation. This study extended the design strategy and the foundation for simultaneous reinforcing and toughening PLA plastics using lignin-derived rubbery micelles.
开发兼具高强度、可延展性和韧性的高性能可生物降解聚乳酸（PLA）材料是目前的研究热点和难点。本工作通过开环聚合将 L（+）-丙交酯（L-LA）和 ε-己内酯（ε-CL）接枝到木质素上，设计并合成了一种新型全生物质基嵌段共聚物。所得木质素-PLA-PCL 嵌段共聚物由刚性木质素和聚（LA-CL）橡胶段组成，通过简单改变共聚物含量可自组装成平均直径为 80-100nm 的均匀纳米胶束。木质素-PLA-PCL 共聚物的加入在 PLA 基体中诱导形成许多空穴，促进 PLA 基体与共聚物之间的自由体积增加，加速链段的迁移能力，使 PLA 复合材料表现出优异的延展性和拉伸性，最大拉伸变形可达 64.8%。共聚物含量低至 5wt%的 PLA 复合材料的强度（41.84MPa）和韧性（8.1MJ/m）分别提高了 6.7%和 1520%。通过研究探索和验证了增强和增韧机制，即空穴生长和纤维化以及基体的广泛剪切屈服，导致了大量的塑性变形。该研究为利用木质素衍生的橡胶胶束同时增强和增韧 PLA 塑料提供了设计策略和理论基础。
