基于重氮盐还原的自修复涂层的构建及防护机理研究

Polyaniline is an important conducting polymer which is used widely in anticorrosion coating. Polyaniline coating has many advantages, e.g. easily synthesized, eco-friendly, excellent chemical stability, thermostability and corrosion inhibition. But, the obtained polyaniline coating with previous methods adheres to carbon steel surface by electrostatic force and it easily peels off from carbon steel surface owing to the weak adhesion between polyaniline coating and carbon steel surface. Therefore, it is important to develop a new method to make polyaniline coating have high adhesion and excellent anticorrosion properties.. In this project, carbon steel surface is grafted a layer of aniline film through electrochemical reduction the diazonium salt of p-phenylenediamine, then the grafted aniline film polymerizes with aniline by electropolymerization or chemical oxidation methods, thus carbon steel surface can be grafted a dense uniform polyaniline coating by covalent bond. The self-healing mechanism of polyaniline coating and the interaction mechanism between polyaniline coating and organic coatings will be investigated by electrochemical analytical and surface analytical methods. . This project not only obtains the reliable data for the solution to the key scientific questions, e.g. preparation of polyaniline coating at carbon steel surface and the self-healing mechanism of polyaniline coating, but also provides new idea and technology for the design of high performance self-healing organic coating system

聚苯胺涂层具有合成简单、环境友好、优良的化学和热稳定性以及腐蚀防护性能等优点。以往方法制得的聚苯胺涂层与碳钢表面通过静电力结合，存在结合力不强，容易脱落的缺点。如何在科学原理上获得突破，实现聚苯胺涂层自修复功能与高附着力的有机统一便成为急需解决的关键科学问题。本项目拟从涂层设计角度出发，采用电化学还原对苯二胺的重氮盐在碳钢表面接枝一层苯胺薄膜，再通过电化学聚合或化学氧化聚合的方法使苯胺薄膜与苯胺共聚，进而在碳钢表面通过共价键接枝一层聚苯胺涂层。利用电化学分析方法和多种表面结构分析方法研究碳钢表面接枝所得聚苯胺涂层的腐蚀抑制行为，阐明其在腐蚀防护中的自修复机理以及与有机涂层间的交互作用机制。本项目的研究成果不仅为碳钢表面聚苯胺涂层的构建及其自修复机理等关键科学问题的解决提供可靠的实验数据，更为高性能自修复防腐涂层体系的设计提供新的思路和方法。

本项目是在国家自然科学基金青年基金的资助下开展的。项目的研究背景瞄准提高涂层与金属界面间的结合力，制备具有自修复功能的涂层体系。本项目从三方面入手开展相关的研究工作：缓蚀剂腐蚀抑制机理的研究、高附着力聚苯胺涂层的构建以及聚苯胺基防锈颜料的合成与腐蚀抑制机理研究。在缓蚀剂研究方面着重研究了不同条件下制备所得植酸转化膜的耐腐蚀行为以及在酸性溶液中单宁酸与碘离子复配缓蚀剂对碳钢的腐蚀抑制作用。研究结果表明在中性植酸溶液中在碳钢表面沉积得到的植酸转化膜比在酸性条件下具有更好的保护性。此外，碘离子的加入能够极大地提高单宁酸的腐蚀抑制能力，碳钢在其中浸泡168h后表面依然比较平整光滑。在高附着力聚苯胺涂层制备方面，我们利用重氮盐的还原在碳钢表面接枝一层类苯胺薄膜，然后采用电化学聚合的方法将聚苯胺涂层接枝到碳钢电极表面，研究结果表明接枝所得聚苯胺具有更高的厚度、更平整的表面和更好的耐腐蚀性能。在聚苯胺基防锈颜料的合成与制备方面，我们制备了一系列基于聚苯胺的防锈颜料，例如：植酸掺杂的聚苯胺，植酸掺杂聚苯胺负载缓蚀剂防锈颜料等。研究结果表明上述基于聚苯胺的防锈颜料均体现出明显的自修复功能。本项目所取得一系列成果将有助于构建新型高性能具有自修复功能的涂层体系提供了新的思路和成果积累。此外，后续一些相应的研究还将逐步展开。