Method for constructing wettability gradient surface by anodization

Abstract

The invention discloses a method for constructing a wettability gradient surface by anodization, belonging to the technical field of surface chemistry. An electrolyte is prepared, a target sample is subjected to surface treatment, and the target sample is subjected to anodicoxidation treatment by a direct-current stabilized-voltage stabilized-current power supply. In the anodization process, the relative positions of an anode and a cathode are adjusted, so that the distances from different positions on the anode to the cathode are different, the current densities of different positions of the target sample are different, and then the current strength and the anodicoxidation time are controlled to obtain the optimal gradient surface. By adopting the method, the magnitude of gradient can be controlled to achieve unidirectional spreading and self driving of liquid drops. One-dimension wettability gradient, two-dimension wettability gradient and certain specific forms of wettability gradient surfaces can be achieved. The method can be applied to various carbon material matrices, and is widely applied. According to the method, the operation is simple, the period is short, and the cost is low and the method can be used for large scale production.

Description

technical field [0001] The invention belongs to the technical field of interface chemistry, and relates to the preparation of a wetting gradient surface by anodic oxidation. The prepared wetting gradient surface can realize unidirectional spreading and self-driving of droplets, and can be further bonded to gradient groups on its surface. Branch-responsive molecules realize the synergistic effect of surface chemical gradients and external stimulus gradients to further increase the degree of self-actuation. Background technique [0002] The study found that the gradient surface can realize the unidirectional spreading and directional driving of droplets, and has a wide range of applications in the fields of diagnostics, microfluidics, fluid power generation, and enhanced heat transfer. At present, the surface gradient is mainly achieved through the surface structure and chemical composition. However, many methods are complicated to operate, time-consuming, labor-intensive and ...

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Problems solved by technology

For example, Kuang-Han Chu et al. (Kuang-Han Chu, Rong Xiao and Evelyn N.Wang. Nature Materials, 2010, 9, 413-417) used the projection lithography technique to etch the silicon wafer deeply with reactive ions to obtain columnar nano-protrusions, and then plated with gold. The nano columnar protrusions are deflected due to residual stress, and then asymmetric nanostructures are obtained, but this method is difficult to operate, it is difficult to control the degree of ion erosion and the deflection degree of the nano columnar protrusions, and it is also impossible to control the gradient on the surface of the substrate. Repeatability, it is difficult to produce large-scale and high-precision

Kunihiro Ichimura (Kunihiro Ichimura, *Sang-Keun Oh, Masaru Nakagawa.Science, 2000, 1624) put the clean silicon wafer into the dilute azobenzene solution, so that the surface is evenly coated with azobenzene molecules, using azobenzene The optical isomerism of molecules under light conditions, the gradient surface is realized through the gradient of light intensity, but the thickness of the azobenzene molecular coating and the change of light intensity are difficult to control

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