湿气触发型自修复聚氨酯涂层的构建及其自修复机理研究

The self-healing coatings using conventional isocyanate microcapsules as a healing agent usually exhibit poor self-healing effects due to the release of CO2 in the self-healing process of the coatings. To solve this issue, a novel moisture-triggered self-healing polyurethane coating will be designed and prepared by embedding isocyanate/oxazolidine compound loaded microcapsule. Once the coating is damaged, the oxazolidine compound flowing out from the microcapsules can react preferentially with water in atmospheric environment, and then the produced active compound bearing amino and hydroxyl can easily react with isocyanate, so realizing self-healing. The study mainly includes the following three parts. (1) The isocyanate/oxazolidine compound loaded microcapsules will be prepared by the combination of Pickering emulsion-template method and thiol-ene click chemistry. Their stability and the reaction between isocyanate/oxazolidine and moisture will be investigated. (2) The moisture-triggered self-healing polyurethane coatings with different compositions will be prepared via the microcapsule embedding technique and the polyurethane synthesis, and their structure and properties will be characterized and analysed, so establishing the composition-structure-properties relationship of the constructed self-healing coatings. (3) The crack growth process and self-healing process of the prepared coatings will be investigated, thereby revealing the self-healing mechanisms of the coatings. The studied results can lay a theoretical and experimental foundation for rationally constructing novel microcapsule-type self-healing coatings or materials.

为解决传统异氰酸酯微胶囊型自修复涂层在自修复过程中会因释放CO2而严重影响自修复性能的问题，将以异氰酸酯/噁唑烷类化合物为芯材的微胶囊包埋于聚氨酯涂层中，利用噁唑烷类化合物会优先与大气环境中的水反应，所生成的含氨基和羟基的化合物又会与异氰酸酯反应的特性，构建一种湿气触发型自修复聚氨酯涂层。研究内容主要包括：（1）采用Pickering乳液模板法，结合巯基-烯点击化学制备以异氰酸酯/噁唑烷类化合物为芯材的微胶囊，研究微胶囊的稳定性和异氰酸酯/噁唑烷类化合物与湿气的反应过程；（2）采用微胶囊包埋法和聚氨酯合成技术制备不同组成的湿气触发型自修复聚氨酯涂层，并对其结构和性能进行表征与分析，建立涂层的组成-结构-性能之间的构效关系；（3）研究涂层的裂纹扩展过程和自修复过程，揭示聚氨酯涂层的自修复机理，为构建新型的微胶囊型自修复材料奠定坚实的理论基础和实验基础。

为解决传统异氰酸酯微胶囊型自修复涂层在自修复过程中会因释放CO2而严重影响自修复性能的问题，将以异氰酸酯-噁唑烷类化合物为芯材的微胶囊包埋于聚氨酯涂层中，利用噁唑烷类化合物会优先与大气环境中的水反应，所生成的含氨基和羟基的化合物又会与异氰酸酯反应的特性，构建一种湿气触发型自修复聚氨酯涂层。研究内容主要包括：（1）光引发巯基-烯点击反应制备了一种新型的以异氰酸酯-噁唑烷类化合物为芯材的微胶囊，微胶囊的形态和尺寸可通过搅拌速率来控制，球形微胶囊的平均直径约为151.4微米，含异氰酸酯-噁唑烷类化合物微胶囊壳层的热稳定性明显高于只含异氰酸酯微胶囊的；（2）采用微胶囊包埋法和聚氨酯合成技术制备了湿气触发型自修复聚氨酯涂层，并对其结构和性能进行了表征与分析，建立涂层的组成-结构-性能之间的构效关系；（3）研究了涂层的裂纹扩展过程和自修复过程，其自修复机理为：涂层裂纹处的微胶囊被破坏，使异氰酸酯-噁唑烷类化合物得以释放，12小时后，形成致密的修复层，从而解决了无催化剂的自修复系统随时可能产生有害CO2的问题，同时证明了以异氰酸酯-噁唑烷类化合物为芯材的微胶囊能有效解决传统异氰酸酯微胶囊型自修复材料在自修复过程中会因释放CO2的问题。本项目研究结果为构建新型的微胶囊型自修复材料奠定了坚实的理论基础和实验基础。