基于磷氮共聚接枝木质素的生物基阻燃剂的构建与构效关系研究

Bio-based flame retardants based on phosphorus- nitrogen-modified lignin have recently emerged as one research focus in the green flame retardancy of polymeric materials. This proposed project aims to address the key issue associated with the lignin-based flame retardants, namely poor comprehensive performances and unclear structure-performance correlation. Based upon previous search, the project proposes to create phosphorus-nitrogen-modified-lignin-based flame retardants by grafting copolymerization with phosphorus- and nitrogen-containing vinyl monomers. The effects of the types of phosphorus- and nitrogen-containing monomers, phosphorus/nitrogen ratios, monomer/lignin ratios and graft parameters on the monomer conversion, and the graft degree, chemical structure and composition, polarity, thermal properties, char-forming capability and the quality of residue chars of lignin-based flame retardants will be investigated, and then the synthetic parameters will be optimized. The loading-level-performance and structure-performance correlations will be clarified by examining the effect of loading levels and chemical structure and composition of as-prepared flame retardants on the flame retardancy of polypropylene and polylactic acid. The project will reveal the flame retardancy mechanism by probing the evolution of the structure, composition and morphology of the products generated during the thermal degradation, burning and char-forming process. The project will also investigate processing and mechanical performances, and establish the correlation between the chemical structure and composition of the flame retardants and the microstructure and overall performances of the resulting composites based on comprehensive analysis, and identify the optimum flame retardant systems for different polymer matrice. The project will provide theoretical support for developing high-performance bio-based flame retardants and their flame-retardant polymer materials.

基于磷氮改性木质素的生物基阻燃剂是当前高分子材料绿色阻燃领域的研究热点。针对其目前存在的构效关系不明和综合性能不佳的关键瓶颈，本项目拟在前期研究基础上，将含磷和含氮的两类烯类单体与木质素进行接枝共聚，构建结构组成可调的磷氮改性木质素阻燃剂。研究含磷和含氮烯类单体的种类、磷/氮比、单体/木质素比和聚合工艺等参数对单体的转化率以及阻燃剂的接枝率、结构组成和极性、热性能、成炭性及炭层质量的影响，优化构建参数。研究阻燃剂的添加量和结构组成对聚丙烯和聚乳酸两种树脂的阻燃作用，阐明其量效和构效关系。考察阻燃剂对基体树脂在热解、燃烧和成炭过程中产物的结构组成与形貌演化的影响，揭示其阻燃机制。研究复合材料的加工性能和力学性能，建立阻燃剂的结构组成与其复合材料微观结构和综合性能间的关联，针对具体基体树脂，确定综合性能最佳的阻燃体系。该项目的研究将为研制高效生物基阻燃剂及其阻燃高分子材料提供技术支撑。

近年来，生物基阻燃剂日益成为环保阻燃剂领域的新宠和研究热点。木质素因多重优势而成为生物基阻燃剂的研究焦点。在木质素分子结构中引入磷氮等阻燃元素是将其转变为高效阻燃剂的重要途径，也是当前高分子材料绿色阻燃领域的研究热点。然而，构建高磷氮含量且极性可调的木质素基阻燃剂并阐明其构效关系已成为制约木质素基高效阻燃剂研发的关键科学瓶颈。针对该关键瓶颈。本项目开展了以下四个方面的研究工作：（1）采用两种丙烯酸酯作为功能单体，通过共聚接枝方法，制备了一种聚丙烯酸酯改性木质素，研究其对聚乳酸力学性能的影响以及增韧机制；（2）设计并合成一种含磷氮乙烯基单体，将其用于共聚接枝木质素制备木质素基阻燃剂，用于聚乳酸阻燃研究，并理解其阻燃机制；（3）在前期基础上，优化设计，合成了一种新型含磷乙烯基单体，将其用于共聚接枝木质素制备了一种木质素基阻燃剂，研究其对聚乳酸的阻燃和力学性能的影响，并明确其阻燃和力学性能的分子机制；（4）最后，进一步优化分子设计，设计并合成含磷乙烯基单体，通过共聚接枝技术制备木质素基阻燃剂，研究其对环氧树脂的阻燃和力学性能的影响，并阐明其阻燃和力学性能的分子机制，建立阻燃剂的结构组成与其复合材料微观结构和综合性能间的关联。该项目的研究为木质素废弃物的高值化利用提供了提供了一条新途径，建立了几种制备新型高效生物基阻燃剂的新方法，深化理解了含磷木质素基阻燃剂的构效关系，为制备环保阻燃高分子材料提供了重要的技术指导和理论支撑。