Self-healing cars? New car coating repairs scratches in 30 minutes using sunlight

The South Korean team that developed this protective coating said that it “self-heals” damaged surfaces using sunlight.

Creating coating that is colorless, transparent, and has a high level of durability has been a challenge for manufacturers until now, the research team of Dr. Jin Chul Kim, Dr. Young il Park, and Dr. Ji-Eun Jeong from the Korea Research Institute of Chemical Technology (KRICT) said in a media release. However, this new material reportedly fills all of those needs and has a similar performance to that of commercial protective coating materials.

To demonstrate its self-healing properties, the researchers coated a laboratory-scale model car using a spray-coating machine. When the model car was exposed to midday sunlight for half an hour, the scratches completely disappeared and the coating material was restored.

This is possible because when sunlight is absorbed by the material, the surface temperature rises as light energy is converted into thermal energy, resulting in the self-healing process which is achieved by repeating the dissociation and recombination of chemical bonds in the polymer structure.

The team added a dynamic chemical bond, known as hindered urea structure, to the existing commercial coating resin in order for it to repeat the decomposition and recombination of the polymer structure. They also mixed it with a transparent photothermal dye to ensure dynamic chemical bonding occurs when exposed to sunlight.

“The developed technology is a platform technology that synthesizes self-healing coating materials using both inexpensive commercial polymer materials and photothermal dyes. It is expected to be widely used not only in automotive clearcoats but also in various applications,” said one of the researchers, Dr. Jin Chul Kim.

Although self-healing functions using photothermal dyes were previously studied, they were mainly based on inorganic materials that are difficult to apply industrially because the coating material must be transparent. Also, inorganic materials usually require a large amount of light energy to produce a photothermal effect.

In the future, the new self-healing material is expected to be used as a coating material for transportation applications, building materials, as well as electronic devices like smartphones.

The study has been published in the journal ACS Applied Polymer Materials.