环氧树脂自修复用纳米复合微胶囊的构建及其多级多样性修复机理研究

Self-healing or self-repairing is one of the most important characteristics of life and also a perfect property for materials. The development and characterization of self-healing synthetic polymeric materials have been inspired by biological systems in which damage triggers an autonomic healing response. This is an emerging and fascinating area of research that could significantly extend the working life and safety of the polymeric components for a broad range of applications. However, conventional microcapsule-based self-healing system has some disadvantages. All of the self-healing concepts attempt to complete healing in a single step either through in-situ curing of a new phase or a permanent resealing of newly exposed surfaces. Time for healing is too long and the healing efficiency is not very high. The emulsions stabilized by particles are called Pickering emulsions. The technology based on Pickering emulsion template is powerful tool to prepare organic/inorganic hybrid microparticles with a core-shell structure, which has a significant potential application in the fabrication for materials with a micro-/nanometer structure. In this proposal, nanocomposite self-healing microcapsules with supracolloidal structures will be prepared by templating nanopartilce-stablized Pickering emulsions. The healing efficiency for their application in epoxy resins will be studies. Materials will be healed with a high healing efficiency in a multi-step solution with multiple healing mechanisms. For example, a broad size distribution of the self-healing microcapsules prepared by this method will have a good help for healing of different cracks with both big and small sizes, which is always happened in the material damage; Inorganic nanoparticles could enhance in-situ the mechanical properties of materials and improve the healing efficiency; Active resins would be used to agglutinate the cracks after the crack surfaces was swelled by solvents; Small cracks would be healed by quick-healing microcapsules with small size, and so on. The target of this research is preparation of polymerical materials with higher performance.

自修复是生物体的重要特征之一，也是材料领域追求的理想目标。通过模仿生物体受损愈合的原理，近年来高速发展的聚合物基自修复复合材料成为高分子科学界的研究热点之一。而传统的微胶囊型聚合物基自修复复合材料存在修复机理和修复过程过于简单、修复时间过长、修复效率不高等缺点。Pickering乳液模板技术可以非常方便地制备核-壳结构的有机/无机杂化微球，在微纳结构材料构建方面具有重大应用前景。本课题采用无机纳米粒子稳定的Pickering乳液为模板制备纳米复合超结构自修复微胶囊。研究其对环氧树脂基材的自修复效果。本项目采用多级多样性自修复机理，实现材料的高效协同自修复，如微胶囊宽的粒径分布适应大小裂纹的修复；无机纳米粒子可以原位增强材料，提高修复效率；采用溶剂先溶胀裂缝表面，再用多种树脂修复剂填充并修复受损区域；快速自修复微胶囊修复小裂纹等等。研究目标是制备性能更加优异的聚合物自修复复合材料。

树脂基复合材料尤其是高性能树脂基复合材料因其优异的物理化学特性、易于加工、价廉等特点，在航空航天、机械和电子工业等领域得到了广泛应用。材料在使用过程中不可避免地会产生局部损伤和微裂纹，并由此引发宏观裂缝而发生断裂，影响材料正常使用和缩短使用寿命。裂纹的早期修复，特别是自修复是一个现实而重要的问题。自修复是生物体的重要特征之一，也是材料领域追求的理想目标。通过模仿生物体受损愈合的原理，近年来高速发展的聚合物基自修复复合材料成为高分子科学界的研究热点之一。而传统的微胶囊型聚合物基自修复复合材料存在修复机理和修复过程过于简单、修复时间过长、修复效率不高等缺点。Pickering乳液模板技术可以非常方便地制备核-壳结构的有机/无机杂化微球，在微纳结构材料构建方面具有重大应用前景。本课题采用无机纳米粒子稳定的Pickering乳液为模板制备纳米复合超结构自修复微胶囊，研究其对环氧树脂基材的自修复效果。其特点是：1. Pickering乳液有非常好的稳定性，能有效地防止乳滴间的凝聚，提高了修复剂的包裹效率；2. 实心纳米粒子层的存在可以提高微胶囊的机械强度和热阻隔性能，还可以在一定的条件下阻止裂纹的扩展。另外，当胶囊破裂时，实心纳米粒子很容易成为应力集中点，在粒子周围会产生很多的微小裂纹，使得胶囊破裂得更为彻底，裂纹的毛细作用会变得更大，修复剂的释放效果会更好；3. 制备的微胶囊粒径分布比传统乳化剂制备的微胶囊宽得多，同时粒径分布范围可以通过调节油水比或胶体粒子的质量分数来控制。小粒径的微胶囊适用于修复尺寸较小的裂纹（早期修复），大粒径的微胶囊适用于修复尺寸较大的裂纹（后期修复），粒径宽分布的微胶囊能够实现对裂纹的多级响应，修复效果会更好；4. 以包覆快速修复剂小粒径微胶囊进一步提高小裂纹的修复。