Self-Healing Polymers

The ultimate in sustainability is finding materials that can repair themselves, and while several researchers have come up with ways to mend small cracks or surface scratches, they have yet to develop something that can regenerate large sections of damaged material, such as the broken leg of a chair. Recently, engineers proposed a model for a composite polymer gel that could do just that by taking inspiration from nature – specifically from amphibians that can regenerate severed limbs.

The model divides the process into three distinct instruction sets. The first is initiation, in which the material senses the removal of material and initiates regrowth. The second is propagation, where the growth continues until it reaches the desired size. The third and final stage is knowing when to terminate the process.

The proposed material is a hybrid of nanorods embedded in a polymer surrounded by a solution of monomers and cross-linking molecules. When a break in the gel occurs, the nanorods adjacent to the cut act as sensors and initiate a polymerization reaction between the monomers and cross-linking molecules, creating a new gel. Complex computational models are used to establish guidelines for terminating the reaction once the break has been sealed.

The model is a first step toward developing even more complex materials and processes with vast practical applications.