Understanding the role of trigger signal spreading, release rate of suitable active agents and their transport rate for optimal healing in extrinsic self-healing materials

在SPP1568的框架下，我们开发了基于氧化还原反应纳米胶囊的新型腐蚀响应自修复材料，即在腐蚀信号开始时释放修复物质的材料，并展示了其作为锌防腐涂层的性能。我们从我们的经验中了解到，外在自愈材料的性能严重依赖于信号的扩散、活性剂的释放速率以及它们到缺陷部位的运输速度。当前项目的目的是从根本上研究这种关系，以便能够设计出最佳的自修复材料。一方面，这将通过系统地改变纳米容器的化学性质和形态来控制释放速度和涂层的性质来影响信号的传播。另一方面，传输速率和愈合速度将由自愈剂的化学性质控制。自修复材料的防腐性能将通过扫描开尔文探针光谱（SKP）等最先进的表征技术进行研究。对于所有与材料无关的外源性自愈材料来说，自愈性能依赖于信号扩散、活性剂的释放及其向缺陷部位的运输速率是一个非常普遍的问题。例如，在White等人展示的第一个外源性自愈材料的例子中，信号传播是裂纹扩展，而愈合速度是由单体运输、容器的大小和浓度以及自愈反应动力学共同给出的。因此，该项目的目标也是将获得的知识应用于SPP1568中活跃的其他小组开发的其他系统，以得出适用于整个外部自愈材料领域的一般结论。

In the frame of the SPP1568, we have developed new corrosion-responsive self-healing materials based on redox-responsive nanocapsules, i.e. materials that released healing substances upon onset of the corrosion signal, and demonstrated their performance as anticorrosion coating for zinc. We have learnt from our experience that the performance of extrinsic self-healing materials is critically dependent on the signal spreading, the release rate of the active agents, and their transport velocity to the defect site. The aim of the current project is to fundamentally investigate this relationship in order to be able to design optimal self-healing materials. This will be done by systematically varying the chemical nature and morphology of the nanocontainers to control the release rate and the nature of the coating to influence the signal spreading,- on the one hand. On the other hand, the transport rate and the healing velocity will be controlled by the chemical nature of the self-healing agents. The performance of the self-healing materials for anticorrosion will be investigated by state of the art characterization techniques such as the scanning Kelvin probe spectroscopy (SKP). The dependence of self-healing performance on signal spreading, release of the active agents and their transport rate to the defect site is a very general problematic for all extrinsic self-healing materials that is material independent. For instance, in the first example of extrinsic self-healing materials shown by White et al., the signal spreading was the crack propagation while the healing velocity was given by the combination of monomer transport, size and concentration of the containers, and kinetics of the self-healing reaction. Therefore, it is also the goal of the project to apply the gained knowledge to other systems developed by other groups active in the SPP1568, to draw general conclusions that are valid for the entire field of extrinsic self-healing materials.