Interphase Percolation Mechanism Underlying Elastomer Reinforcement

Glassy interphase has been claimed to be of vital importance for mechanical reinforcement of elastomer nanocomposites (ENCs), but the evolution of interphase topology in correlation to reinforcement percolation remains uncertain. Here, an accurate interfacial regulation strategy upon implementing an interphase percolation mechanism is exploited to realize percolation of mechanical performance toward striking elastomer reinforcement. Architecture design of interfacial metal–ligand bridges accomplishes firm anchoring between elastomer skeleton and carbon nanodots, leading to the formation of interfacial metal-enriched regions. The volume fraction of the interfacial region systemically enlarges upon increase of interfacial bridges, which finally overlaps with neighboring domains to form a penetrating interphase. The topological evolution of the interfacial region is quantitatively monitored upon small-angle X-ray scattering and dielectric measurements, which exhibits a similar percolation behavior in sync with that of macroscopic mechanical performance. Furthermore, the interphase exhibits much slower relaxation dynamics than in bulk polymer, which significantly improves the network rigidity and hence accounts for the prominent elastomer reinforcement. This investigation corroborates that the formation of penetrating interphase may be an executable mechanism to induce the reinforcement percolation of ENCs. We further envision that the implementation of interphase percolation mechanism can be a universal avenue to afford rationalized optimization of ENCs.