Preparation Of Magnetic Roughness Surface And Characterization On Hydrophobicity

Wettability is one of the basic characteristics of the material,which decided by surface free energy and the surface morphology,and it derives two directions of hydrophilicity and hydrophobicity.Low surface free energy is the precondition for hydrophobicity,and the surface morphology is the controlling factor.The understanding of superhydrophobicity is originated from the nature.Being inspired,the biomimetic superhydrophobic materials with special characteristics such as fluid drag reduction,anti fogging,anti icing and self-cleaning have been attracted great attentions,and have shown attractive application prospect in many fields of production and life.Low surface energy modification and rough surface construction are utilized to achieve superhydrophobic surface.In recent years,superhydrophobic materials have been obtained by microstructural methods such as template method,deposition method,and etching method,etc.However,due to limitations such as high device requirement,complicated operation,high cost,difficult to make large area preparation and environmentally unfriendly,the superhydrophic surface did not used as widely as expected.Therefore,innovating the preparation method and simplifying the process to obtain a material with superhydrophobic surface will continue to be the focus of research in the future.Based on the wettability theory and magnetic control forming mechanism,this paper prepares magnetic rough surface(MRS)superhydrophobic film using the magnetic roughening technology,and its hydrophobicity is investigatied.The details are as follows:(1)The basic concept of wettability and the typical superhydrophobic phenomena in nature are introduced,and then the application prospects of superhydrophobic surfaces is analyzed.The research of biomimetic hydrophobic surface technology is reviewed,and the significance and content of the research are proposed.(2)The magnetic control forming mechanism is analyzed,and the relations with the strength and gradient of external magnetic field,particle size of magnetic particles,the content of magnetic particles and magnetic susceptibility are concluded.The preparation method of magnetic rough surface is explored,and based on it,multiple samples are prepared with the Polydimethylsiloxane as the flexible carrier and carbonyl iron as the dispersion phase.(3)The theory of wettability is introduced,and the regular sawtooth structure model for MRS is established,in which the effect of aspect ratio and spacing ratio on the hydrophobicity of the surface is analyzed.The wetting behavior of water droplets on the sawtooth surface are simulated by COMSOL.The results show that the higher aspect ratio and smaller spacing ratio of surface microstructures are beneficial to improve the surface hydrophobicity.(4)The MRS was characterized using scanning electronic microscopy(SEM)and contact angle instrument.The results show that the micrometer-sized mountainous protrusions are randomly distributed at the surface of MRS,and the contact angle increases from 110° to 158.2°,with different magnetic intensity in the preparation,which designates a status of superhydrophobicity.Further tests show that with the rolling angle less than 10°,the sample surface has self-cleaning properties.MRS sample is stable for superhydrophobicity and is firmly bonded to the matrix.Finally,the influences of the magnetic field,particle size and content of carbonyl iron,film thickness on the hydrophobicity of MRS are experimentally described,and the control factors for MRS hydrophobicity were further clarified.