生物质基石墨烯量子点制备及其在聚乳酸复合材料中的应用基础研究

Graphene quantum dots (GQDs) with low cytotoxicity and distinct optoelectronic properties are opening avenues to diverse applications in the biomedical and photoelectric fields. Using rice or corn straws as the natural carbon source, we attempt to prepare renewable and degradable GQDs through the combination of microwave-assisted hydrothermal method and acidic oxidation treatment. It is of significance to explore the structure transformation mechanism, as well as the controlling method of the size and surface chemical structure. Further, the GQDs could be homogeneously incorporated into poly(lactic acid) (PLA) by solvent compounding and melt shear, enabling the realization of high heat resistance and mechanical strength and toughness, while sustaining the good degradability of PLA. It moreover allows the nanocomposites to inherit the unique optical properties of GQDs, e.g., high transparency, excellent UV shielding and tunable fluorescence. Investigation of the effects of filler dispersion morphology, matrix−filler interfacial adhesion and crystalline morphology on the mechanical, thermal and optical properties of nanocomposites allows us to establish the morphology−property relationships for nanocomposites functionalized by 0D carbonaceous nanostructures. The research would offer novel guidelines for the low-cost manufacture of biobased nanoscale carbonaceous materials, as well as the development of high-performance and multifunctional PLA, in great need for expanding the application range of PLA materials.

石墨烯量子点(GQDs)是具有低生物毒性和优异光电性质的环境友好型碳纳米材料，在生物和能源领域展现了广阔应用前景，但其在构筑功能化聚合物复合材料的探索尚处于初期阶段。申请人以水稻/玉米秸秆为天然碳源，结合微波辅助水热法和酸氧化处理制备可再生、可降解的GQDs，研究GQDs的结构转变机理、物理尺寸和表面化学结构的调控手段。通过“溶液共混-熔体剪切”法制备聚乳酸/GQDs复合材料，研究填料分散形态、填料-基体界面相互作用和基体结晶形态对聚乳酸复合材料高性能化（高耐热性、高力学强度和韧性）和功能化(高透明性、高UV屏蔽性能和独特荧光性质)的影响机制。揭示GQDs结构、GQDs-基体界面相互作用和基体结晶形态与聚乳酸复合材料力学、热学和光学性能的构效关系，为低成本制备生物质基碳纳米材料及其复合材料的实用化提供新思路。

石墨烯量子点(GQDs)是具有低生物毒性和优异光电性质的环境友好型碳纳米材料，在生物和能源领域展现了广阔应用前景，但其在构筑功能化聚合物复合材料的探索尚处于初期阶段。本项目成功以水稻/玉米秸秆为天然碳源，制备了物理尺寸和化学结构可控的GQDs（粒径约为2nm，高度低于5.5nm）和生物质固体红光材料，是一种典型的零维材料。并且该红光材料可以用于防伪、荧光涂覆等领域。进一步，本项目研究填料分散形态、填料-基体界面相互作用和基体结晶形态对聚乳酸（PLA）复合材料高性能化（高耐热性、高力学强度和韧性）和功能化(高透明性、高UV屏蔽性能、疏水性能和独特荧光性质)的影响机制。揭示GQDs结构、GQDs-基体界面相互作用和基体结晶形态与PLA复合材料力学、热学和光学性能的构效关系。研究结果显示GQDs促进了PLA结晶，其结晶度与纯PLLA（14.6%）相比，提高至41.6%；相对纯PLA，复合材料强度提高了34.4%；该荧光新材料的荧光性能表明该材料在410nm和663nm处表现出最佳激发，且该荧光材料具有非激发依赖特性，其在670nm和720nm时均为6.1ns的荧光寿命；此外，PLA材料疏水角高达155.7oC,可用于油水分离和抗冰等领域。