Which materials repair themselves?

Self-healing materials were once the work of science fiction, but nowadays, those silver screen ideas are flourishing in the real world.
Interesting Engineering

Sci-fi fans definitely know a thing or two about self-healing materials that have been seen on the silver screen. The definition of self-healing materials is pretty simple as it comes from the term itself. These are materials that repair themselves after being subjected to damage. However, the science behind how self-healing materials work is hard and a work in progress.

Self-healing materials can be categorized under four types: materials with embedded healing agents, materials with a kind of internal vascular circulation, shape-memory materials, and reversible polymers. 

In 2022, Scientists have developed an eco-friendly, self-healing nanocrystal semiconductor. This happened while researching toxic-free alternatives to commonly used lead halide perovskites because of the government ban on metal halide perovskites use. The particles were observed by Sasha Khalfin and Noam Veber under a transmission electron microscope. Researchers studied how the holes created due to the electron beam's effect on the nanocrystals of perovskite nanoparticles interacted with the materials around, moved, and changed within them.

The lab of Yehonadav Berkenstein produced perovskite nanoparticles with self-healing properties. This was observed as the nanocrystal returned to its original structure upon removing organic molecules coating the surface. These molecules allow the movement of formed holes into stable areas inside, and when removed, the holes are then ejected to the surface and out, leading to the observed healing phenomenon. 

Currently, the self-healing properties of materials depend on numerous factors, including material type, size, and shape of nanoparticles. Several applications are being studied to see how these self-healing properties in materials could be utilized. 

Electrical grids need dielectric polymers to insulate wires properly, but electrical treeing can lead to structural damage to the said materials. Affected sections can be "healed" by adding superparamagnetic nanoparticles to the thermoplastic polymer, as studied by scientists. 

The next application of self-healing can be seen in lithium-ion rechargeable batteries, which are common among electronic devices. To make the battery safe, University of Illinois researchers developed a self-healing electrode that triggers a response in the microcapsules and disperses the crack-filling substances as batteries degrade. 


Lastly, researchers are developing a flexible, nanoparticle-based sensor with self-healing properties to work with frequently used machines to maintain function. 

The current developments we have regarding self-healing materials are still far from achieving the likes of those that can be seen in films. However, these developments prove that we are on the way to achieving such goals. Maybe soon, a damaged phone screen will automatically fix itself and return to pristine condition.