Design of Dual Hybrid Network NaturalRubber–SiO2 Elastomers with Tailored Mechanicaland Self-Healing Properties

摘要

The preparation of natural rubber (NR)–silica (SiO2) elastomeric composites with excellent mechanical properties along with better self-healing ability remains a key challenge. Inspired by the energy dissipation and repairability of sacrificial bonds in biomaterials, a strategy for combining covalent and noncovalent sacrificial networks is engineered to construct a dual hybrid network. Here, the approach used to fabricate the composites was self-assembly of NR, bearing proteins and phospholipids on its outer bioshell, with SiO2 via metal-ion-mediated heteroaggregation effected by reversible electrostatic and H-bonds. Further, covalent cross-links were incorporated by a silane coupling agent, bis [3-(triethoxysilyl) propyl] tetrasulfide. The intrinsic self-healing ability of the composite at the molecular level was studied by broadband dielectric spectroscopy that unraveled the mechanism of the healing process. The synergistic effect between the molecular interdiffusion of the cross-linked NR chains and the electrostatic and H-bonding interactionsimparted an exceptional self-healing characteristic to the liquid–liquid-mixing-preparedNR–SiO2 composites with improved mechanical performance.Specifically, the segmental relaxation dynamics of the healed compositewas largely restricted due to increased number of ion–dipoleinteractions and S–S cross-links at the junction of the cutsurface. We envisage that this extraordinary healing property, unreportedyet, would be of great importance toward the design of novel NR–SiO2 elastomeric hybrids with superior mechanical properties.