Strengthening and toughening styrene-butadiene rubber by mechanically interlocked cross-links

Styrene-butadiene rubber (SBR) is an indispensable material in modern society, and the necessity for enhanced mechanical properties in SBR persists, particularly to withstand the rigors of challenging environmental conditions. To surmount the limitations of conventional cross-linking modes, mechanical bonds stabilized by host-guest recognition are incorporated as the cross-linking points of SBR to form mechanically interlocked networks (MINs). Compared with covalently cross-linked network, the representative MIN exhibits superior mechanical performance in terms of elongation (1392%) and breaking strength (4.6 MPa), whose toughness has surged by 17 times. Dissociation of host-guest recognition and subsequent sliding motion provide an effective energy dissipation mechanism, and the release of hidden length is also beneficial to enhance toughness. Furthermore, the introduction of the rotaxane cross-links made the network more pliable and possess damping and elastic properties, which can return to initial state with one minute rest interval. We aspire that this direct introduction method can serve as a blueprint, offering valuable insights for the enhancement of mechanical properties in conventional commercial polymer materials.