Humanity has realized that the available resources and energy needs to be consumed more efficiently to live in a sustainable society. A topic of research that tackles this issue is related to the synthesis of so-called self-healing materials, i.e. materials able to heal at least partially damages that they may suffer. The concept of self-healing materials is a paradigm shift in materials science and leads the academic and industrial community to new exciting advances and benefits. The contribution of our group of chemists in VISTEC is the creation of unique new self-healing materials based on smart nanocapsules.

Our main interest is to create materials that can autonomously self-repair, i.e. that can heal without external human intervention and at room temperature. Therefore, we developed new methods for the encapsulation of reactive agents such as monomers and catalysts in inorganic [1] or polymer nanocapsules [2-4] that can be used in a self-healing reaction and for which the release can be triggered by mechanical damage or environmental stimuli.

Moreover, our approach is very versatile and a very wide range of materials can be used as core and shell for building the smart nanocapsules such as organic or inorganic shell and polymer or liquid cores. The nanocapsules surfaces were functionalized with various chemical groups [1-3] to enhance their compatibility with the host matrix. Moreover, stimulus-responsive materials, i.e. materials responsive to changes of pH value, redox conditions, or temperature, were synthesized and used as nanocontainers to allow for selective release of the healing agents. Such nanocontainers can be further embedded in coatings to yield materials with self-healing abilities (see Figure 1).

Figure 1. Scanning electron microscopy cross-section images of smart nanocontainers embedded in an acrylate coating at different magnitudes (a-c). From reference [5].