高性能木质素/橡胶复合材料界面牺牲键的构建、机理和性能研究

Lignin, a primary constituent of all higher plants, is considered to be the second abundant renewable biomass resource in nature. Rubber polymer is one of the most important materials to national economy and security. Lignin/rubber composite, a value-added application for lignin, has attracted hot attention in both industrial and academia community. Using lignin as a replacement of the conventional rubber filler carbon black is highly competitive due to its natural abundance, low density, cost competiveness, and more importantly, excellent UV-resistant and anti-aging performance. However, to realize the reinforcement of rubber by lignin, two urgent problems need to be resolved: poor dispersibility of lignin in rubber and poor interfacial compatibility between lignin and rubber matrix. Sacrificial bonds, a key structural factor determining the fascinating properties of some natural materials such as spider silk and mussel byssus, can undergo reversible rupture and reconstruction before covalent bonds break. We believe that the strength and toughness of lignin/rubber composite would be significantly improved by the sacrificial bonds. In this proposal, with the introduction of “reactive compatibilizer”, the metal-ligand coordination-based sacrificial bonds will be constructed in the interfacial phase between lignin nanoparticle and rubber matrix. The effect of sacrificial bonds on the interaction force and compatibility between lignin and rubber molecules will be detailed studied. The theoretical foundation will be revealed for the function of sacrificial bonds in the interfacial phase. The mechanism of performance manipulation will be further illustrated for lignin/rubber composite in existence of sacrificial bonds. Through the implementation of this proposal, a novel method for the preparation of lignin-based rubber composite will be established, which will lay a foundation for the mass application of lignin in polymer materials.

木质素是自然界第二大生物质资源，具有优异的抗紫外辐射与抗老化性能。橡胶是国民经济与高科技发展不可或缺的重要国防战略物资。利用木质素增强橡胶，不仅可以降低成本，同时能提高橡胶的抗紫外辐射、抗老化性能，还可以推动生物质资源的高值高效利用。要实现木质素增强橡胶，迫切需要解决木质素在橡胶基体中的分散性差、与橡胶相的相容性差等关键科学问题。受启于生物仿生研究中的能量牺牲键机理，本项目将借助反应性相容剂的作用，在木质素纳米粒子与橡胶的相界面中构建金属离子配位牺牲键，利用牺牲键先于化学键断裂且具有动态断裂与重构的特性，大幅提高复合材料的强度及韧性。重点研究能量牺牲键对木质素与橡胶分子之间作用力及相容性的影响规律，揭示牺牲键在木质素与橡胶相界面间作用的理论机理，进而阐明牺牲键对木质素/橡胶复合材料的性能调控机制，建立木质素/橡胶复合材料制备的新方法，为实现木质素资源在高分子材料中的大规模应用奠定基础。

橡胶是重要的国防战略物资，传统的橡胶补强主要依赖于炭黑，成本高、能耗大。木质素是自然界第二大生物质资源，具有优异的紫外屏蔽与抗老化性能。利用木质素部分替代炭黑来增强橡胶，不仅可以降低成本，同时能提高橡胶的抗紫外辐射、抗老化性能，还可以推动生物质资源的高值高效利用。但是，木质素的补强效果远不及炭黑。要实现木质素增强橡胶，迫切需要解决木质素在橡胶基体中分散性差、与橡胶相的相容性差等关键科学问题。.受启于生物仿生研究中的能量牺牲键机理，本研究通过在木质素纳米粒子与橡胶弹性体的相界面间构建动态能量牺牲键，重点研究了牺牲键对木质素与橡胶基体界面相容性的影响规律，揭示了能量牺牲键能有效提高木质素与橡胶相界面间的作用力、提高界面相容性，并促进木质素在橡胶基体中的分散，利用牺牲键动态断裂与重构的特性，大幅提高木质素与橡胶弹性体复合材料的强度及韧性。通过构建界面能量牺牲键，成功制备了高性能木质素/丁腈橡胶复合材料、木质素/丁腈橡胶/PVC橡塑复合材料、木质素/三元乙丙橡胶复合材料、木质素/聚乙烯热塑性弹性体复合材料，所得复合材料拉伸强度均超过20MPa，并且当木质素替代一半的炭黑填料时，拉伸强度和韧性能达到甚至超过纯炭黑的水平，抗热氧老化性能优于纯炭黑填料。构建界面能量牺牲键的方法还成功拓展应用于高性能木质素基聚氨酯弹性体的制备以及高性能全降解木质素/聚乙烯醇复合材料的制备，均取得了很好的效果。本研究建立了木质素/橡胶弹性体复合材料制备的新方法，为高性能木质素/高分子复合材料的配方设计和构效调控提供了科学指导。