VELCRO-INSPIRED SUPRAMOLECULAR SYSTEM FOR SILICA–RUBBER COUPLING

The state-of-the-art silica–rubber coupling is based on forming chemical links between a silica surface and rubber macromolecules. However, the chemical links are relatively short and stiff, thus in case of a chemical breakage they are highly unlikely to recombine. This could result in a potential deterioration of the interphase properties over time. To overcome this drawback, a new approach to silica–rubber coupling was investigated in the current study. The new approach is inspired by the Velcro hook-and-loop system from nature that facilitates a re-connectability, thus re-formation of the interphase properties in case of a breakage. For this, various long oligomeric brushes were grafted onto silica surfaces considered to act as supramolecular hooks. Such modified silica were dispersed in rubber and vulcanized. The resulting cross-linked rubber matrix is considered to act as supramolecular loops. The prepared vulcanizates were compared with reference samples containing common coupling or covering agents. The reinforcing potential provided by the newly developed system is lower than the chemical coupling system but considerably higher than the covering system. The new system also provides better mechanical properties, recovery after cycling stretching, and heat treatment than the references. A new reinforcing mechanism is proposed for the silica grafted with oligomeric brushes that exhibits a good chemical compatibility to the rubber matrix.