Surface-functionalized Fillers as Dynamic Crosslinkers

Rubber waste management has received extensive concern in the circular economy. To realize waste rubber recycling, dynamic linkages that can undergo reversible breaking and reformation in response to external stimuli are introduced to replace traditional irreversible crosslinks in vulcanized rubbers. Filler is an essential component in rubber processing, while the incorporation of high loading of fillers inevitably deteriorates the dynamic network recyclability by hindering chain movement and preventing the collision of dynamic motifs. To overcome the contradiction between reinforcement and recyclability arising from filler incorporation, dynamic bonds are creatively installed at the interface of dynamically crosslinked rubbers (DCRs) by using functionalized fillers as both reinforcement and dynamic crosslinkers. The mechanical properties of DCRs are generally improved by constructing dynamic bonds across the interface due to improved filler dispersion and enhanced interfacial adhesion. Simultaneously, dynamic bonds at the interface enable the rubber chains adsorbed on fillers to participate in network rearrangement under external stimuli, which may alleviate the negative effect on recyclability imposed by filler incorporation. In this chapter, we summarize the recent progress on the construction of dynamic bond-mediated interfaces in DCRs and the effect on the mechanical and dynamic properties.