Self-healing through microcapsules in the paint

Self-healing surfaces sound like science fiction, but they are real. Fraunhofer scientists from polymer research provide insights into so-called active substances and their mode of action.

Will unsightly scratches on vehicle paintwork soon be a thing of the past? The potential of microcapsules is high: they protect against corrosion, UV radiation or make unsightly scratches disappear. They are incorporated into the paint and contain an active substance. If the paint is damaged, the capsules burst open, the active substance escapes and does its work. The substances prevent the scratch from spreading, for example. In this interview, researchers from the Fraunhofer Institute for Applied Polymer Research IAP in Potsdam and the Fraunhofer Institute for Manufacturing Engineering and Automation IPA reveal how this works, what the capsules are made of, how they get into the paint and what else they can be useful for.

Researchers at the institutes are working with active substances consisting of corrosion inhibitors, lubricating oils, adhesive components or combinations of these three active substances. The wall material of the microcapsules can consist of cross-linked or non-cross-linked polymers, but also of inorganic silicon or titanium dioxide and combinations thereof. One of the challenges in the formulation of the microcapsules is the phase behaviour of an emulsion. The material for the core can be contained in one phase and the material for the shell in the other. The shell then grows at the phase boundary under suitable conditions. Another challenge lies in the nature of the microcapsules themselves: On the one hand, you want capsules that open at the right moment. On the other hand, they should be as robust as possible during processing, i.e. not burst open. Process expertise and experience are necessary to achieve this. Other exciting fields of application include corrosion protection, self-healing conductor tracks or microcapsules that contain antimicrobial substances or UV protection agents.