Interesting. What's weird is that polymers typically degrade under UV light. Think way back to when you used those play-school shovels and left them out in the sand for a couple days. I guarantee that you saw some cracks.<p>One of my favorite professors here is doing research on self-healing metals. It's pretty sweet. They're using magnesium alloys for structural self-healing applications because magnesium exhibits a martensitic transformation (i.e it changes shape when you heat it). Oddly enough, martensitic metals are used in bra-supports so that they return to their original shape when washed, yet still give good support.<p>I love materials science.