Tannic acid-modified TiO₂/PU elastomers with dual-functionality: enhanced mechanical and electrorheological performances combined with triboelectric sensing

Abstract Conventional polydimethylsiloxane (PDMS) based electrorheological elastomers (EREs) show significant limitations, including inadequate load-bearing capacity and a lack of multifunctionality. To overcome these challenges, this study proposes a dual-functional elastomer combines ER performance with triboelectric functionality through an interface design strategy, in which tannic acid (TA) is used to modify titanium dioxide (TiO₂) particles and then dispersed in a polyurethane (PU) matrix. The results confirm that the TA modification significantly enhances the interfacial compatibility between TiO₂ and PU, improving the mechanical properties; specially, the 20TiO₂@TA-PU demonstrates a tensile strength increase of 96.6% and fatigue resistance compared to the 20TiO₂-PDMS. Furthermore, the superior dielectric properties of the TiO₂@TA particles reinforce the interactions among the particles when subjected to an electric field, resulting in an ER effect of 143% at an electric field strength of 3 kV mm⁻¹, which is much higher than the 31% observed in PDMS-based EREs. The electron affinity characteristics regulated by TA simultaneously enhance the triboelectric performance, with the open-circuit voltage reaching 151 V. This research provides a viable approach for the development of advanced materials that combine electric-field-responsive mechanical properties with self-powered sensing functionalities.