Biphasic synergistic enhancement hydrogels via modulus-matched rubbery and entangled phases

Biphasic hydrogels hold significant potential in fabricating isotropically tough materials through structural synergy, yet their strength remains constrained by interfacial modulus mismatch. Herein, a modulus-matched rubbery and entangled phases synergistic enhancement strategy is proposed to construct biphasic hydrogels by continuous phase separation. The molecular chain aggregates of the rubbery and entangled phases with nano crystalline domains are induced by continuous phase separation via reducing solvent polarity and breaking polymer-solvent hydrogen bonds, respectively. The key to achieving synergistic enhancement lies in modulus matching between the rubbery and entangled phases. Biphasic synergistic enhancement hydrogels exhibit excellent mechanical properties including a tensile strength of 38.76 MPa, a toughness of 137.03 MJ m −3 , a modulus of 58.36 MPa, and a fracture energy of 130.21 kJ m −2 . Biphasic hydrogels exhibit a low strength decay of 2.73% during ten cycles of testing at a strain of 3. Crucially, the modulus-matched biphasic system with crystalline domains transcends the stiffness-fracture energy trade-off boundary. The biphasic hydrogels exhibit heat resistance and stable electrical conductivity, making it suitable for flexible wearable electronics. It can function as a high-performance epidermal bioelectrode for monitoring human electromyography signals, demonstrating the integrated advantages of its strength, flexibility, reversible deformability, heat resistance, and stable ionic conductivity. Biphasic synergistic enhancement strategy paves the way for development of ultrastrong biphasic hydrogels via modulus matching.