Finding a scratch on your car is a special kind of heartbreak, but in the future, it might disappear before you even know it. Korean scientists have developed a coating that automatically repairs scratches in just 30 minutes when exposed to sunlight.
The new coating contains an acrylic polyol-based polymer network, with what is called a hindered urea structure. Essentially, polymers have dynamic chemical bonds that can break in response to stimulus and then reform back into their original arrangement, effectively repairing minor damage like scratches. In this case, the trigger is heat, which is provided by an organic photothermal dye that picks up infrared light, also embedded in the coating.
In tests on a model car, the team showed that the coating healed scratches in 30 minutes of midday sunlight. In theory, this means someone could lock your car door and the scratch could be gone before you get back.
If half an hour is too long, the team has also demonstrated that the process can be dramatically accelerated under concentrated light. Using a magnifying glass to focus sunlight on the mark fixed it in less than 30 seconds.
The team says the new coating has a few advantages over existing self-healing coatings. Using organic photothermal dyes means it needs far less energy to operate than regular inorganic versions, which typically require heat guns or concentrated UV lamps. Others, like Nissan’s Scratch Shield, work in milder conditions but can take up to a week. The new coating can also repair a scratch in the same place multiple times, unlike self-healing materials that work using bursting resin capsules.
It is important to note that the new coating is clear so it will not mar the color of the paint job and can be applied using existing spray coating methods. Although cars are the primary use case, the team says it could also be applied to other often-scratched devices like phones or building materials.
The research was published in the journal ACS Applied Polymer Materials. The team demonstrates the self-healing coating in the video below.
Self-healing car model covered with developed varnish when exposed to concentrated sunlight