基于超分子层间交换响应的钢筋靶向阻锈体系构建和机制研究

As a significant strategic issue for marine power construction, it is imperative to extend the service life of reinforced concrete infrastructure. Importantly, the integration of both structure and function of corrosion protection materials holds great promise for the durability enhancement of reinforced concrete. Our research group has carried out a series of projects sponsored by National Natural Science Foundation of China to work on this topic. Based on the previous findings, this project proposes the necessity and theoretical feasibility to hypothesize a novel type of organic migrating corrosion inhibitor (MCI) with the integrated multi-function. Through probe modification and intercalation assembly, the first aim is to fabricate supermolecular materials with targeted corrosion inhibition function by embedding a chloride-ion-triggered switch which is able to control MCI release. Moreover, the second aim is to elucidate the exchange mechanism between MCI and chloride ion within supermolecular multilayers by means of single-molecule tracking. In the third aim, taking advantages of in situ microscopic analysis and non-destructive monitoring visualization, we plan to reveal the mechanism of chemical reaction between supermolecular inhibitor and reinforced steel in marine corrosive environment, the transporting mechanism of targeted corrosion inhibition in concrete, as well as the influence to evolution of concrete microstructure. We expect that this strategy would achieve an integrated and synergistic multi-function of environment adaption, chloride ion management, and rebar protection in the supermolecular structure, which allow us to overcome disadvantages of traditional passive defense strategy. The promotion of this project would not only improve the theoretical foundation of corrosion control to reinforced concrete failure, but also provide effective guidance to durability design and life cost optimization of marine infrastructure.

钢筋混凝土基础设施服役寿命的延长已成为建设海洋强国亟须解决的重大战略问题，而腐蚀防护材料的结构功能复合化正是钢筋混凝土耐久性提升研究领域中的前沿热点。基于申请人主持和参与的国家自然科学基金系列成果，本项目提出有机迁移型阻锈剂多功能一体化发展的必要性及理论可行性，拟通过探针修饰和插层组装，在超分子结构中嵌入可调控阻锈剂释放的氯离子触发开关，构建钢筋靶向阻锈体系，阐明阻锈剂与氯离子在超分子层间的识别和交换机制，进一步通过原位微观分析表征和无损可视化追踪监测，揭示海洋腐蚀环境下超分子阻锈体系与钢筋的化学反应机理，在混凝土中的靶向传输机制，以及对混凝土微观结构演变的影响规律，实现阻锈体系对环境适应、氯离子治理、钢筋防护功能的集成和协同，克服片面注重被动防护所带来的深刻弊端。项目实施将丰富和完善钢筋混凝土结构腐蚀失效控制的理论研究基础，对海洋基础设施耐久性设计和全寿命成本优化形成有效指导和切实保障。

传统的类水滑石超分子（LDH）制备方法耗时耗力，缓释插层效率低下，离子交换无靶向性，且与有机涂层基体之间存在不相容性，导致在分散性较差。围绕LDH的合成、缓蚀负载以及其与有机涂层基体之间的界面相互作用，结合先进和全面的微观表征技术，致力于构建一套集绿色、高效、功能化于一体的靶向缓蚀−自修复涂层防护体系。具体的研究内容如下：.（1）.在LDH的可控合成与生长机制方面，结合LDH的合成反应机理，探讨了反应气氛、生长温度、时间、pH以及层间阴离子对LDH的形貌、结构和组成的影响。结果表明，溶液和空气中的CO2都可以参与LDH的合成反应生成CO32− 并插层到LDH层间，且其与LDH层板的结合优先级明显的高于NO3−。生长温度和时间主要影响LDH的晶粒尺寸。pH（OH− 浓度）对LDH的形成具有非常重要的作用，在适当的pH（10 ± 0.5），可以获得典型的片状的LDH。.（2）.在提高缓蚀剂的负载率方面，利用LDH的记忆效应，创新性的通过剥离−重构法合成了高负载量有机缓蚀剂（5−甲基−2−巯基−1,3,4−噻二唑，MTT）的LDH。结果表明，重构后的产物不仅能够恢复LDH典型的层状结构，而且还可以获得纯净的MTT− 插层的LDH。此外，通过剥离-重构制备的LDH，其缓蚀剂的负载量相比于离子交换法提高了约3倍，并且其对Cl− 还具有快速的响应释放性能。.（3）.在提高LDH与涂层基体的相互作用方面，提出了三种高效的分散策略：首先，创新性的引入石墨纤维（GF）来提高LDH与涂层基体的相互作用： LDH在涂层基体中存在明显的团聚现象，会引入较多的缺陷；而OGF/LDH在PVB基体中具有较好的分散性，呈单根交错分布。其次，基于单层LDH纳米片制备了仿生多层杂化膜，通过自下而上法直接合成了大量、均匀的单层LDH纳米片（LDH-NS），然后通过一步共组装法制备了类珍珠层的多层杂化膜。最后，制备集优异的屏障和自修复性能于一体的LDH基功能化仿生复合涂层，防腐性能提高了5个数量级，且自修复性能显著。