Abstract Achievement of macroscale superlubricity from the hydration effect could provide a potential application for artificial articular cartilage. In this work, two zwitterionic polymers, 2-methacryloyloxyethyl phosphorylcholine (MPC) and sulfobetaine methacrylate (SBMA), were used to synthesize a P(MPC-co-SBMA) copolymer hydrogel through the additional polymerization of the alkane carbon-carbon double bond. The incorporation of MPC promoted the water-binding property of copolymer hydrogels as well as improved their anti-compression capability. A superlubricity state with a friction coefficient of approximately 0.002 was achieved when a P(MPC-co-SBMA) copolymer hydrogel hemisphere slid on a sapphire in water, which demonstrated its dependence on sliding velocity, load, and aqueous lubricants. The superlubricity mechanism was mainly attributed to the hydration effect from zwitterionic MPC and SBMA polymer chains, which led to the formation of a uniform hydration layer on the hydrogel surface and the strong adsorption of water molecules on the sapphire surface, which provided additional stabilized hydration layers. These findings might provide insight into the superlubricity mechanism of zwitterionic hydrogels based on the hydration effect, thereby broadening their extensive applications.

中文翻译：

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两性离子共聚物水凝胶和蓝宝石在水中实现宏观超润滑

摘要 通过水化作用实现宏观超润滑性可为人工关节软骨提供潜在的应用。在这项工作中，两种两性离子聚合物，2-甲基丙烯酰氧基乙基磷酰胆碱 (MPC) 和磺基甜菜碱甲基丙烯酸酯 (SBMA)，用于通过烷烃碳-碳双键的额外聚合合成 P(MPC-co-SBMA) 共聚物水凝胶。MPC的加入促进了共聚物水凝胶的水结合性能，并提高了它们的抗压缩能力。当 P(MPC-co-SBMA) 共聚物水凝胶半球在水中的蓝宝石上滑动时，实现了摩擦系数约为 0.002 的超润滑状态，这表明它依赖于滑动速度、载荷和水性润滑剂。超润滑机制主要归因于两性离子 MPC 和 SBMA 聚合物链的水化作用，导致水凝胶表面形成均匀的水化层，蓝宝石表面对水分子的强吸附，提供了额外的稳定水化层. 这些发现可能有助于深入了解基于水合效应的两性离子水凝胶的超润滑机制，从而拓宽其广泛应用。