单宁酸基单分子膨胀型阻燃剂的构建及其对硬质聚氨酯泡沫的阻燃和增强作用研究

Considering the key technical problem existed in flame-retardant rigid polyurethane foams that the high flame retardancy and excellent mechanical-related properties is difficult to satisfied simultaneously, in this project, based on the molecular design and reaction parameters optimization, we will design and synthesize a series of single-molecule intumescent flame retardant polyols with controlled structure by grafting different triazine derivatives and phosphorus-containing compounds onto the skeleton of industrial scale bio-renewable tannic acid. The flame retardants will be covalently incorporated into polyurethane in the curing process to acquire tannic acid-based inherently flame-retardant rigid polyurethane foams. We will systematically investigate the influence of the molecular structure and loading of flame retardants on the processing properties, thermal stability, flame retardancy, smoke suppression and mechanical properties of rigid polyurethane foams. Accordingly, we will establish the structure-activity relationships between "synthesis parameter", "controllable structure" and "overall performance", and hence propose an effective solution to resolve the contradiction between the non-flammability and good mechanical properties. Meanwhile, we will monitor the variation of the chemical structure and composition of the decomposition products in both gas and condensed phase during thermal degradation process by online analytical technology to extrapolate the char-forming behavior, and finally clarify the flame retardant mechanisms. This project is expected to provide theoretical guidance and technical reference for not only the molecular design of high-efficient and multi-functional biomass-based flame retardants, but also the preparation of polyurethane with high fire safety as well as well-balanced comprehensive performances.

针对目前硬质聚氨酯泡沫阻燃化存在的阻燃与力学等关键性能难以兼顾的共性科学难题，本项目结合天然生物基单宁酸优异的分子设计性，通过结构设计和反应参数调控，将不同类型的三嗪衍生物和含磷阻燃单体接枝到单宁酸骨架上，合成多种结构可控的“三源一体”单宁酸基单分子膨胀型阻燃多元醇，并将其以化学键合方式引入到聚氨酯分子链中，构筑本质阻燃硬质聚氨酯泡沫材料。系统研究阻燃多元醇分子结构对硬质聚氨酯泡沫成型工艺以及热、阻燃、抑烟和力学等性能的影响，构建合成参数-可控结构-性能调控之间的内在关联，提出解决高效阻燃和力学增强这一难题的有效途径；探索阻燃硬质聚氨酯泡沫在热降解过程中气相和凝聚相产物组成、结构的动态演变及成炭行为，并揭示其阻燃作用机理。该项研究将为高效、多功能的生物基阻燃剂的设计开发及高性能本质阻燃聚氨酯材料的制备提供科学依据和技术借鉴。

聚氨酯是一种用途广泛的有机高分子材料，但属于易燃材料，燃烧过程往往释放大量浓烟和有毒气体并伴随严重的熔融滴落行为，对生命安全和环境造成潜在危害。本项目针对目前聚氨酯阻燃化存在的阻燃与力学等关键性能难以兼顾的共性科学难题，基于膨胀型阻燃剂的构成要素，通过结构设计和反应参数调控，设计并合成了多种富含多羟基结构的集碳源、酸源和气源“三源一体”的单分子膨胀型阻燃剂，进而构筑了一系列阻燃聚氨酯材料。研究结果表明，单分子膨胀型阻燃剂显著降低了聚氨酯燃烧过程中的热释放和烟气生成量，LOI值可达27%以上，UL-94垂直燃烧测试通过V-0等级，表现出优良的阻燃、抗熔滴和抑烟减毒性能；火灾安全性能的提升主要归因于凝聚相阻燃机制，同时辅以气相阻燃机制；此外，单分子膨胀型阻燃剂不同活性的多羟基结构可同时与聚氨酯基体形成共价交联网络以及氢键等非共价键作用，显著提升了聚氨酯的力学强度，且良好地保持其断裂伸长率。因此，本项目的开展实现了聚氨酯高效阻燃和力学增强的协同兼顾，为高性能阻燃剂的设计开发以及综合性能优异的阻燃聚氨酯材料的调控构筑提供了理论依据和学术基础。