Super-hydrated supramolecular hydrogel with persistent minimal friction enabled by zwitterion-driven microphase separation

A fundamental challenge for lubricating hydrogels is the inherent trade-off between mechanical robustness and interfacial hydration, necessitating new approaches to achieve both properties. To address this, we engineered an ultra-high strength novel supramolecular lubricating hydrogel leveraging zwitterion-driven microphase separation strategy. The supramolecular lubricating hydrogel P(NASC-co-MPC) was fabricated through a two-step procedure: dissolution of the strong H-bonding N -acryloylsemicarbazide (NASC) and the zwitterionic 2-methacryloyloxyethyl phosphorylcholine (MPC) in a DMSO/H 2 O mixed solvent, subsequently phase separation-induced H-bonding reconstruction triggered in deionized water. The mechanical properties of the P(NASC-co-MPC) supramolecular hydrogels can be tailored by varying the molar fraction of MPC, yielding tensile strength from 5.47 to 8.76 MPa and Young’s modulus from 19.90 to 98.50 MPa, alongside compressive strength from 5.15 to 9.03 MPa and compressive modulus from 8.25 to 22.40 MPa at 50% strain. Interestingly, the incorporation of additional MPC facilitates the interfacial hydration capacity of P(NASC-co-MPC) supramolecular hydrogels, leading to improved lubrication performance. The resulting best-performing P(NASC-co-MPC) hydrogel exhibits extremely exceptional lubrication performance (friction coefficient as low as 0.057) under physiological conditions, comparable to natural articular cartilage. This supramolecular hydrogel design strategy provides a versatile proposal for developing advanced lubricating materials potential in cartilage repair, anti-adhesion barriers, and anti-fouling coatings.