Tie Lu, Guo Zhiguang, Liu Weimin
†State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000, China.
‡Hubei Collaborative Innovation Centre for Advanced Organic Chemical Materials and Ministry of Education Key Laboratory for the Green Preparation and Application of Functional Materials, Hubei University, Wuhan 430062, China.
ACS Appl Mater Interfaces. 2015 May 20;7(19):10641-9. doi: 10.1021/acsami.5b03533. Epub 2015 May 7.
Controlling oil of wettability behavior in response to the underwater out stimulation has shown promising applications in understanding and designing novel micro- or nanofluidic devices. In this article, the pH-manipulated underwater-oil adhesion wetting phenomenon and superoleophobicity on the micro- and nanotexture copper mesh films (CMF) were investigated. It should be noted that the surface exhibits underwater superoleophobicity under different pH values of the solution; however, the underwater-oil adhesion behavior on the surface is dramatically influenced by the pH value of the solution. On the basis of the thermodynamic analysis, a plausible mechanism to explain the pH-controllable underwater-oil adhesion and superoleophobic wetting behavior observed on a micro- and nanoscale semicircular structure has been revealed. Furthermore, variation of chemistry (intrinsic oil contact angle (OCA)) of the responsive surface that due to the carboxylic acid groups is protonated or deprotonated by the acidic or basic solution on free energy (FE) with its barrier (FEB) and equilibrium oil contact angle (EOCA) with it hysteresis (OCAH) are discussed. The result shows that a critical intrinsic OCA on the micro- and nano- semicircular texture is necessary for conversion from the oil Cassie impregnating to oil Cassie wetting state. In a water/oil/solid system, the mechanism reveals that the differences between the underwater OCA and oil adhesive force of the responsive copper mesh film under different pH values of solution are ascribed to the different oil wetting state that results from combining the changing intrinsic OCA and micro-/nanosemicircular structures. These results are well in agreement with the experiment.
响应水下外部刺激来控制油的润湿性行为在理解和设计新型微纳流体装置方面已显示出有前景的应用。在本文中，研究了在微纳纹理铜网薄膜（CMF）上pH调控的水下油粘附润湿现象和超疏油性。应当指出的是，在溶液的不同pH值下，该表面呈现水下超疏油性；然而，表面上的水下油粘附行为受到溶液pH值的显著影响。基于热力学分析，揭示了一种合理的机制来解释在微米和纳米级半圆形结构上观察到的pH可控的水下油粘附和超疏油润湿行为。此外，还讨论了由于羧酸基团被酸性或碱性溶液质子化或去质子化而导致的响应表面化学性质（固有油接触角（OCA））的变化对自由能（FE）及其势垒（FEB）以及平衡油接触角（EOCA）及其滞后（OCAH）的影响。结果表明，微米和纳米半圆形纹理上的临界固有OCA对于从油Cassie浸渍状态转变为油Cassie润湿状态是必要的。在水/油/固体体系中，该机制表明，在溶液不同pH值下，响应性铜网薄膜的水下OCA和油粘附力之间的差异归因于由固有OCA变化与微米/纳米半圆形结构相结合所导致的不同油润湿状态。这些结果与实验结果吻合良好。
