基于原位溶胶-凝胶法的木材-有机-无机杂化纳米复合材料可控制备规律与界面结合机制

Ordinarily, the organic polymer modified wood possesses poor thermal stability and higher brittleness, and the inorganic compounds are difficult to separately endow wood with satisfied mechanical strength. With the purpose of overcoming these disadvantages, and inspired from the organic-inorganic hybrid nanocomposites, the project proposes a novel scientific research proposal idea. It is investigating the preparation of a novel wood-organic-inorganic hybrid nanocomposite with excellent properties combined the advantages of both organic polymer and inorganic compounds modified wood via the in-situ uniform nanohybridizaiton of organic and inorganic moieties within the natural pores of wood. It intends to constitute the organic functional monomer system and the inorganic system by designing the molecular structure, and to optimizely control the degree of phase separation between organic and inorganic components and their bonding interfaces with wood by sol-gel process, and to synergisticly endow wood with high-strength mechanical properties and excellent durability as well as functions under specific structures and morphologies by homogeneous nanohybridization of the three phases. Modern analysis means and material properties evaluation are combined to reveal and highlight the controllable preparation law of the nanocomposites and the interface bonding mechanism among the organic polymer, inorganic compounds and wood, which could provide important scientific foundation for controlling preparation of novel modified wood with excellent properties and even specific functions. Such study is also innovation significance for exploring new method of wood modification and enriching theoretical system of wood-based composites.

为克服传统有机聚合物改性的木材热稳定性差、脆性高和无机化合物改良木材难以有效赋予力学强度的不足，受有机-无机杂化纳米复合材料启发，本研究提出了"利用有机体和无机体在木材天然孔隙内与木材基质原位杂化纳米复合方法，探索制备兼具有机聚合物和无机化合物改性木材优点的高性能新型木材-有机-无机杂化纳米复合材料"的技术构思，拟通过分子结构设计理论构建有机功能性单体体系和无机体系，并采用原位溶胶-凝胶法，优化调控有机体与无机体的相分离程度及其与木材的复合界面，借助三者的均匀杂化纳米复合协同赋予木材高强力学性能和优异耐久性，及特定结构形态的功能性。利用现代分析手段结合材料性能测试，探明木材-有机-无机杂化纳米复合材料的可控制备规律及有机聚合物、无机体和木材彼此间的界面结合机制，为可控制备高性能与功能特性改良木材提供重要的科学依据，对探索木材性能改良新途径、丰富木质复合材料理论体系具有创新意义。

木材自古以来即是一种常用的建筑结构材料。然而，近年来，它却因各国实施的森林保护工程面临供不应求的境地，而大量种植的速生树种木材却因过快生长而致结构强度锐减；再加木材本身固有的受热降解、遇水变形、易于腐朽等问题，致使当今市场上的木材难以直接做轻质高强的结构材料。.受木材多孔结构的启发，在速生低质木材中通过原位杂化技术生成有机-无机纳米杂化聚合物，做增强体可望有效改善木材的缺陷。为此，本研究通过分子结构设计构建了有机功能体系使生成的有机体具有含部分柔性链段的立体交联链结构，并通过化学键接枝到木材细胞壁上，形成一体，以赋予木材高强度和高韧性；同时，将无机体通过Sol-Gel法精确裁剪调控到直径为50nm以下，并键合到有机体结构中，形成浑然一体的木材-有机-无机纳米复合材料。这种材料的初始热解温度和最大热降解温度较未处理木材分别提高55oC和53oC，呈现良好的热稳定性；其抗弯强度、抗压强度、硬度和防腐失重率分别较未处理木材提高83％、156％、208％和97%，其连续浸水228h的抗胀率高达47％，整体上具有优良的热稳定性、力学性能、尺寸稳定性和防腐性能，可作为一类新型的轻质高强结构材料用于建筑、包装、装修、交通运输等领域，环保节能、可再生循环。. 该研究中最大的理论和技术难点在于有机体与无机体两相在纳米尺度的复合调控及与木材的界面结合机制。为此，研究中采用了SEM、AFM、NMR、FTIR、XRD、TG/DTG等表征分析手段，解析了反应机制，初步构建了结构调控规律：含两个及以上的不饱和双键、一个以上的柔性链段和一个以上的环氧官能团；无机体系在含不饱和双键的硅烷偶联剂调控下，形成界面相容的有机-无机体系。这为后续以此为基础延伸的超疏水自清洁、刺激响应型有机-无机杂化功能/智能木材提供了理论依据和实践探索。