Metal-ion-mediated healing of gels

Abstract

Several researchers have demonstrated the biomimicking attributes of stimuli responsive synthetic hydrogels such as sensitivity, selectivity, mobility, and memory. In this work we demonstrate yet another attribute, namely healing in hydrogels. We show that certain hydrogels having a flexible aliphatic side chain with a terminal carboxyl group can show healing in the presence of transition metal ions. On bringing two initially dried gel pieces into contact with each other in a dilute copper chloride solution the pieces were found to weld and the strength of the weld-line was found to increase gradually with time. The welded gel pieces could be separated by leaching out the metal ions and the separated gel pieces can be welded again by subsequent treatment with the metal ions.