Enhanced electromechanical properties of natural rubber using highly efficient and cost-effective mussel-inspired modification of TiO2 nanoparticles

Recently, dopamine and its secondary function are being used as the intermediate to tailor the surface molecular structure of high-dielectric-constant nanoparticles, which improves interfacial interaction of dielectric elastomer (DE) composites, due to their versatile adhesion properties. However, the high-cost of dopamine limits the large-scale applications of DE. Herein, a mussel-inspired modification of TiO2 nanoparticles is presented to prepare high-performance natural rubber (NR) DE composites by replacing dopamine with cheaper poly(catechol/polyamine) (PCPA). First, the TiO2 nanoparticles were deposited with PCPA. Then, the PCPA-coated TiO2 nanoparticles were further grafted with γ-methacryloxypropyl trimethoxy silane (KH570), which contains double bonds and denoted as TiO2-PCPA-KH570. Owing to the presence of CC bonds, the TiO2-PCPA-KH570 nanoparticles participated in the vulcanization of NR and the TiO2-PCPA-KH570/NR composites exhibited enhanced filler dispersion and interfacial interaction, leading to the improved mechanical, dielectric, and electromechanical properties. Furthermore, the 10 phr TiO2-PCPA-KH570/NR composite resulted in the largest actuated strain of 12.3%, which is ~2 times higher than that of the largest actuated strain of pure NR (6.0%). The present study provides a high-efficient and cost-effective route to obtain DEAs with enhanced electromechanical properties. •A catechol/polyamines co-deposition and KH570 grafting has been proposed to modify TiO2 nanoparticles.•The modification of TiO2 nanoparticles enhanced filler dispersion and interfacial interaction of NR composites.•NR composites filled with modified TiO2 nanoparticles displayed improved mechanical and electromechanical properties.•The largest actuated strain of 12.3% is achieved by 10 phr TiO2-PCPA-KH570/NR composites.