Self-healing and thermoreversible rubber from supramolecular assembly

When a rubber-band breaks, that's it: time to get another one. But a remarkable new material described in this issue behaves rather differently. Consisting of molecules containing three different functional groups that form multiple hydrogen bonds, the molecules associate to form a 'supramolecular rubber' containing both chains and cross-links. The system shows rubber-like behaviour, that is, recoverable extensibility when stretched to several times its original length. In contrast to conventional rubbers made of macromolecules, these systems when broken or cut can self-heal when the fractured surfaces are brought together at room temperature. The new material can be synthesized from simple ingredients — fatty acids and urea — and once synthesized it is readily reprocessed. In its current form supramolecular rubber has slow strain recovery and it 'creeps' under stress, but by adjusting the starting ingredients, a spectrum of properties is attainable.