Synergistic Interface Engineering of Dopamine and SDBS for Constructing High-Performance Graphene/Sponge Composites With Enhanced Stability and Sensitivity

Despite significant advances in sponge-based pressure sensors for wearable devices and human-machine interfaces, achieving a sponge composite that simultaneously delivers ultrahigh sensitivity, a broad detection range and long-term mechanical stability remain a critical challenge, largely owing to the weak interfacial adhesion between the conductive nanofiller and the sponge skeleton. Herein, we demonstrate a robust interface engineering strategy for a multifunctional composite essentially consisting of a polydopamine (PDA)-modified polyurethane (PU) sponge and sodium dodecyl benzenesulfonate (SDBS)-functionalized graphene. The PDA coating affords a positively charged surface rich in catechol and amino groups, whereas SDBS imparts negative charges and stable dispersibility to graphene. First-principles density functional theory (DFT) calculations reveal the interfacial interactions and electronic structure evolution between the PDA@PU sponge and Gr@SDBS nanosheets, revealing synergistic hydrogen bonding and electrostatic attraction that ensure strong adhesion and uniform graphene decoration. Such a robust interface established by multiple noncovalent interactions facilitates the conformal and uniform decoration of graphene onto the 3D PU skeleton, thereby establishing a highly stable and continuous conductive pathway. The resulting Gr@SDBS/DPA@PU sponge composite delivers an outstanding sensitivity (6.46 kPa-1), a wide detection range (up to 550 kPa), a rapid response time (31.1 ms), and exceptional cyclic stability (up to 5000 cycles). Furthermore, by integrating a miniaturized wireless Bluetooth module, the sensor enables accurate real-time monitoring of finger joint movements and wireless gesture-based remote human-machine interaction. This work provides mechanistic insights into interface engineering of graphene/sponge composites and establishes a novel paradigm for smart wearable electronics.