Self-healing coatings by reversible crosslinking: Mechanistic investigations of defined model systems on the molecular level using linear and non-linear Raman microspectroscopy

聚合物涂层对于每个现代社会都是必不可少的，它可以保护无数产品的表面。引入自愈特性将对这些材料的使用寿命产生重要影响。尽管存在第一个具有自愈特性的商业涂层，但其潜在的分子过程还远未被理解。提出的项目的中心目标是阐明依赖于可逆交联的涂层中自我修复的潜在分子机制，特别是可逆Diels-Alder （DA）环加成。在这个项目中，我们提出(i)使用一种新型的含有二烯呋喃和亲二烯马来酰亚胺的聚合物，同时改变取代模式以调整愈合温度和愈合效率，以及（ii）研究一种新型的杂dials - alder反应（硫酮/二硫酯与二烯）用于自修复应用。这两种类型的交联系统将通过线性和非线性拉曼显微光谱结合二维相关分析进行详细的研究。对于自我修复系统，这种方法尚未被描述；它将允许对受损和未受损地区进行调查，从而区分两者。作为自愈过程的触发因素，主要是利用热量；在对基本原理和机理的进一步了解的基础上，还将研究其他的活化剂。

Polymer coatings are essential for every modern society, protecting surfaces of an uncountable number of products. The introduction of self-healing properties would have an important impact on the lifetime of these materials. Even despite the fact that first commercial coatings with self-healing properties exist, the underlying molecular processes are far from being understood. The central target of the proposed project is the elucidation of the underlying molecular mechanisms of self-healing in coatings relying on reversible crosslinks, in particular on reversible Diels-Alder (DA) cycloadditions. In this project we propose (i) the usage of a new type of polymer containing both the diene furan and the dienophile maleimide, while varying the substitution pattern to tune the healing temperature as well as the healing efficiency, and (ii) the investigation of a new type of a hetero-Diels-Alder reactions (thioketones/dithioesters with dienes) for self-healing applications. Both types of crosslinked systems will be investigated in detail by linear and non-linear Raman microspectroscopy in combination with two-dimensional correlation analysis. For self-healing systems, such an approach has not yet been described; it will allow the investigation of damaged and non-damaged areas and, therefore, the differentiation between both. As a trigger for the self-healing process, primarily heat will be utilised; additional activators will be investigated based on the attempted increased knowledge of the basic principles and mechanisms.