Diffusion- and mobility-controlled self-healing polymer networks with dynamic covalent bonding. Fundamental study of reversible thermosets from bulk to thin layers.

This project will center around reversible organic network systems that can be used for self-healing applications. Such networks are dynamic, and distinguish themselves from conventional organic networks by the inclusion of Diels-Alder bonds, which can reversibly switch between a bonded and de-bonded state according to a chemical equilibrium. To achieve acceptable mechanical properties, network materials often need to have a sufficiently high glass transition temperature, turning them into low-mobility glasses at ambient conditions. As a result, it is usually assumed that for self- healing to occur elevated temperatures are required. Recently we discovered that self-healing still occurs below the glass transition, under so-called diffusion-controlled conditions. A study of the network formation process under such conditions in several bulk model systems is therefore a first goal of this project. Such a study has never before been attempted on reversible (self-healing) systems. Several advanced thermal analysis techniques are available in our lab to perform this study. In addition, thin layers of
such networks will be studied, using highly advanced chip calorimetry techniques. The thin layer nature is expected to influence the dynamics of the network. The feasibility of powder coatings made
with reversible networks will be studied. This study will improve the fundamental understanding of these systems, as well as lead to practical knowledge for (coating) applications