Zwitterionic materials have attracted increasing attentions in the underwater super‐oleophobic applications for its strong hydration via electrostatic interactions. Herein, molecular dynamics simulations were used to investigate the hydration and underwater oleophobicity of sulfobetaine‐terminated self‐assembled monolayers (SB‐SAMs) with different carbon spacer lengths (CSL) between oppositely charged groups of SB molecules. Simulation results show that the hydration of SB‐SAMs is positively dependent on CSL; the underwater oleophobicity is strengthened and then weakened with the increase of CSL, reaching optimal performance when CSL = 3; adhesion force of oil droplet on SB‐SAMs is inversely correlated with their contact angles, reaching the minimum value when CSL = 3. Moreover, the addition of NaCl can weaken the self‐association of SB molecules resulted from interactions between cationic and anionic groups, which promotes hydration and enhances underwater oleophobicity of SB‐SAMs. These results will benefit for the design of novel zwitterion‐based materials for anti‐fouling and oil–water separation applications.

中文翻译：

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两性离子自组装单分子膜的水合作用和水下疏油性的分子模拟

两性离子材料由于其通过静电作用而具有强水合作用，因此在水下超疏油应用中受到越来越多的关注。在这里，分子动力学模拟被用来研究磺基甜菜碱封端的自组装单分子膜（SB-SAMs）的水合和水下疏油性，这些分子在带有相反电荷的SB分子组之间具有不同的碳间隔长度（CSL）。模拟结果表明，SB-SAMs的水合作用正相关于CSL。随着CSL的增加，水下疏油性增强，然后减弱，当CSL = 3时达到最佳性能。油滴在SB‐SAMs上的附着力与它们的接触角成反比，当CSL = 3时达到最小。NaCl的添加会削弱由阳离子和阴离子基团之间的相互作用导致的SB分子的自缔合，从而促进水合作用并增强SB-SAMs的水下疏油性。这些结果将有助于设计用于防污和油水分离应用的新型基于两性离子的材料。