内源型金属自修复防护体系的构建及其持久自修复防护机制研究

The self-healing function of an anticorrosion protective system is pivotal for corrosion protection of metallic materials. The current self-healing anticorrosion protective systems are based on the extrinsic self-healing mechanism by preventing corrosion propagation through releasing corrosion inhibitors from micro/nanocapsules, which demonstrate barely-satisfactory self-healing protective performance. To strengthen the self-healing protective functions of the anticorrosion protective systems, in this proposal, the smart self-healing anticorrosion protective systems based on the intrinsic self-healing mechanism by repairing the damage through the reversibility of noncovalent interactions will be developed and the corresponding internal driving mechanism for the durable self-healing protection will be elucidated...Such intrinsic self-healing anticorrosion protective system will be constructed by the following strategy. First, the ideal polymer architecture blocks for building the intrinsic self-healing protective layer with suitable degree of polymerization will be designed based on the quantum chemistry calculations and molecular dynamics simulations. Then, the techniques of hydrothermal pre-treatment, layer-by-layer (LbL) assembly and chemical bath deposition will be employed to construct the intrinsic self-healing anticorrosion protective systems with durable self-healing protection...To elucidate the internal driving mechanism for the durable self-healing protection of the above intrinsic self-healing anticorrosion protective systems, some local in situ techniques such as SVET (Scanning Vibrating Electrode Technique), SECM (Scanning Electrochemical Microscope) and AFM (Atomic Force Microscope), will be used to monitor the smart self-healing process; The XPS (X-ray Photoelectron Spectroscopy), Raman and IR spectroscopic techniques will be used in characterization of the self-healing interfacial characters; Specifically, CLSM (Confocal Laser Scanning Microscope) will be used to monitor the flowing process of dynamic polymer chains. Based on the above characterization results, the internal driving mechanism for the durable self-healing protection will be proposed...The constructing approach proposed here will demonstrate a practical way for surface treatments of metallic materials. The constructed anticorrosion protective systems in this project will provide durable self-healing protection for metals and alloys, which will undoubtedly promote the applications of metallic materials in various fields especially in some harsh environments.

目前的金属自修复防护体系均是基于外源型自修复机制，存在自修复功能弱、组分相容性差等根本缺陷。为克服上述缺陷，本项目拟以高强铝合金和镁合金为典型防护对象，利用一些聚合物成膜材料自身组成物质间的可逆化学、物理作用，构建新颖的内源型金属自修复防护体系并研究其作用机制：.(1)基于量子化学计算和分子动力学模拟设计具有高效缓蚀作用、结构稳定且分子链能适度迁移的理想的聚合物防护膜成膜体系，联用水热技术、层层组装技术、化学浴沉积技术构建与金属基底结合牢固、耐摩擦磨损、具有持久自修复功能和优异防护性能的内源型金属自修复防护体系。(2)采用SVET、SECM、AFM、XPS、Raman、IR、CLSM等多种原位/微区技术获取自修复界面的动态特征及自修复过程中聚合物链的动态变化，揭示持久自修复防护作用的内在驱动机制。.本项目的开展将为金属的自修复防护提供新思路，对发展实用先进的金属表面技术具有重要指导作用。

受自然界生物体伤口可自行修复的启发，人们将自修复理念引入到金属防护中，自修复防护已经成为金属防护的重要发展方向。然而目前的金属自修复防护体系基本是基于外源型自修复机制，存在自修复功能弱、组分相容性差等根本缺陷。.针对上述问题，本项目构建了内源型金属自修复防护体系并研究了其作用机制。主要研究内容及结果包括：(1)基于文献调研、理论计算和初步实验结果，确定了“底膜-自修复聚合物外膜”的内源型金属自修复防护体系的构建策略，并确定聚乙烯亚胺（PEI）和聚丙烯酸（PAA）作为自修复聚合物外膜的构筑基元。利用上述策略，联用水热技术、层层组装技术，成功构建了内源型金属自修复防护体系。进一步通过在聚合物外膜成膜过程中引入无机纳米粒子SiO2，并与常用防腐涂料环氧树脂复合，制备了具有实际推广应用价值的复合改性内源型金属自修复防护体系。(2)利用场发射扫描电子显微镜（FESEM）、原子力显微镜（AFM）、接触角仪（CA）、X射线光电子能谱（XPS）、红外光谱(IR)、拉曼光谱（Raman）、共聚焦激光扫描显微镜（CLSM）等技术表征了样品的表面形貌、粗糙度、润湿性、组成和价键结构以及聚合物分子在膜中的扩散行为。利用数字显微镜原位观察系列损伤-修复测试中划痕的动态修复过程，证实构建的内源型金属自修复防护体系具有修复速度快、修复程度高和可重复修复的特点，多次划伤、砂纸磨损、高温破坏和有机溶剂浸泡测试结果证明该自修复防护体系具有很好的机械稳定性、热稳定性和化学稳定性，腐蚀介质浸泡和电化学阻抗谱测试结果显示体系具有优异的防护性能。(3)基于压痕载荷、吸水能力、聚合物分子扩散等测试结果以及分子动力学对膜层自修复过程的模拟结果，探明了构建的防护体系实现自修复的内在驱动机制，修复过程由PAA的扩散主导，并带动PEI的扩散从而实现修复。.上述结果对于发展金属智能防护技术，拓展金属材料在严酷环境中的应用至关重要。