Simultaneous polymerization constructing Hydrogel-Elastomer composites with ultra-tough interface for robust epidermal mechanoreceptor

Seamlessly integrating responsive hydrogel with antagonistic elastomer is paramount and desired for developing multi-layered architectures with high complexity, which shows predominating potentials in biomimetic electronic mechanoreceptor. Here, we introduce a facile yet universal simultaneous polymerization (STP) strategy achieved by the synergy of simultaneous self-polymerization of hydrogel and elastomer systems, and competitive copolymerization at interface region. Such a strategy forges an ultra-tough and durable interface with an interfacial toughness up to ∼ 1100 J/m² for hydrogel-elastomer composites (HEC), while avoiding the complex stepwise polymerization process of both layers. The STP strategy universally exercises on toughening the interfaces between a wide range of interior hydrogels (e.g., PAAm, PAA, PDMAA and PAMPS based) and exterior elastomers (e.g., PEA, PHFEA, and PMEA based). Such a robust interface fulfills the delocalization of interfacial stress and high-fidelity transfer to interior hydrogel during deformation, leading to exceptional responsiveness and cyclic stability. The quantitative correlations between interfacial toughness and sensing properties guide the design of mechano-receptor with high sensitivity, sparking promising prospects in epidermal signals monitoring.