How can a material heal itself back to it’s original state, fixing scratches and sealing small holes? Well for some polymers it all comes down to a bit of carbonIn one of my earlier posts we looked at the three different types of self healing material. The most interesting option out of the three, at least in my opinion, is the intrinsic healing. A healing factor that doesn’t rely on glues, or microbes built into the material but uses an innate ability of the material to seal scratches.
How does it work?
This power comes from the polymers structure. Namely how the hydrocarbon inside it are formed, when a cut occurs the cross linked chains are broken and the material tries to regain these bonds. The material can then connect with itself again, seeking out these bonds and completing them. Once these bonds have been healed they act as if they had never been broken. In fact in most cases you will find that there is little if any weakness introduced. Currently most materials require a heat source to heal back fully. The examples both require incubation to return to full strength this is to give the hydrocarbon bonds the energy to reform.
This reforming is different to melting the material, the material at no point becomes a liquid instead it uses the energy to remake the bonds. Most of the current solutions require either heat, pressure or both to remake the material. This is to ensure the material has the energy to fix itself. The only other constant is that in all cases healing takes time to occur. Most healing is not instant or a better way to think is that while the healing begins instantly it takes a little while to rise to full strength. This is particularly important for the first two examples below which aim to make the material as strong as it was before, pulling it apart before the material has set could lead to all sorts of issues.
Below is great example of a self healing polymer that requires heat treatment to recover but once heated loses any visible damage. However this particular silicone requires heating to 90 degrees for 24 hours to be fully cured.
There’s also this video that covers a self healing material with a much lower activation energy of 37 degrees Celsius
Finally if you want to see it in a product there has recently been a screen protector developed for iphones that can heal scratches in the surface. It’s almost blasphemous to see them deliberately scratch the screen but gives a real glimpse into the future as it heals up.