Underwater Polymer Healing

Biocompatible polymers in medical implants deal with shocks and strains, but these plastics frequently fail before other materials in replacement teeth, bones, and joints. Polymers with the ability to repair themselves could extend the lifetimes of implants. But most self-healing polymers falter in watery physiological conditions, and those that don’t are usually weak to begin with. Scientists at the University of California, Santa Barbara, have now developed sturdy self-healing polyacrylate and polymethacrylate materials that rely on water to facilitate repairs (Nat. Mater. 2014, DOI: 10.1038/nmat4037). B. Kollbe Ahn, Dong Woog Lee, Jacob N. Israelachvili, and J. Herbert Waite fabricated polymer rods with surfaces functionalized with silyl-protected catechols. This functionalization is even present on the new surfaces formed when a rod is sliced in two. By rinsing the two rod sections with a buffer solution, researchers strip away triethylsilyl groups blocking the catechol groups. They then rejoin the rod sections in water, with the catechols now free to form multivalent hydrogen bonds with one another. These interfacial hydrogen bonds initiate a healing process that propagates through the material, completely restoring the polymer’s strength.