Self-healing materials are substances that can knit themselves back together after being torn or broken. Here you can see a new self-healing hydrogel that could revolutionize how we treat internal wounds to the stomach.
Hydrogels are squishy polymer chains that look something like gummi bears. They are very useful in medicine, because they contain so much water they're as flexible as biological tissues. Now, new research out of UCSD offers a way to make these gels stick together with incredible strength. Researchers pulled off this trick by adding dangling hydrocarbon side chains to the polymer network that makes up the gel. With these in place, exposure to an acidic environment causes the self-healing hydrogel to knit together (exposure to a basic one makes it separate again).
That means that two pieces of the hydrogel can be stitched together, or damaged areas can knit together, simply by exposing it to environments of pH 3 or lower for just two seconds. High pH environments split it apart again, but the process can be repeated many times without ill effect. Not only that, but the strength of the bond is impressive. After just 10 seconds of bonding the join can take 2 kPa of stress - and when it breaks, it breaks in the middle of the gel, not at the join. The material continues to strengthen for up to 24 hours of exposure to the acid, eventually being able to handle 35±3 kPa of stress.
The potential applications of this are just freaking incredible — but some of the most interesting possibilities lie in medicine, especially for treating stomach wounds. After all, the gut is an acidic environment. You could hold closed stomach perforations until they heal, knowing that the hydrogel would heal itself from any damage due to the constant low pH exposure.
Image credit: Joshua Knoff, UC San Diego Jacobs School of Engineering