A novel super-hydrophobic stearic acid(STA)film with a water contact angle of 166° was prepared by chemical adsorption on aluminum wafer coated with polyethyleneimine(PEI)film. The micro-tribological behavior of ...A novel super-hydrophobic stearic acid(STA)film with a water contact angle of 166° was prepared by chemical adsorption on aluminum wafer coated with polyethyleneimine(PEI)film. The micro-tribological behavior of the super-hydrophobic STA monolayer was compared with that of the polished and PEI-coated Al surfaces.The effect of relative humidity on the adhesion and friction was investigated as well.It was found that the STA monolayer showed decreased friction,while the adhesive force was greatly decreased by increasing the surface roughness of the Al wafer to reduce the contact area between the atomic force microscope(AFM)tip and the sample surface to be tested.Thus the friction and adhesion of the Al wafer was effectively decreased by generating the STA monolayer, which indicated that it could be feasible and rational to prepare a surface with good adhesion resistance and lubricity by properly controlling the surface morphology and the chemical composition.Both the adhesion and friction decreased as the relative humidity was lowered from 65% to 10%,though the decrease extent became insignificant for the STA monolayer.展开更多
The microstructure, wettability and chemical composition of the butterfly wing surfaces were investigated by a scanning electron microscope, a contact angle meter and a Fourier transform infrared spectrometer. The mic...The microstructure, wettability and chemical composition of the butterfly wing surfaces were investigated by a scanning electron microscope, a contact angle meter and a Fourier transform infrared spectrometer. The micro/nano structural models for hydrophobicity of the butterfly wing surfaces were established on the basis of the Cassie equation. The hydrophobicity mechanisms were discussed from the perspective of biological coupling. The butterfly wing surfaces are composed of naturally hydrophobic material and possess micro/nano hierarchical structures, including primary structure （micrometric scales）, secondary structure （nano longitudinal ridges and lateral bridges） and tertiary structure （nano stripes）. The wing surfaces exhibit high hydrophobicity （contact angle 138°-157°） and low adhesion （sliding angle 1°-3°）. The micromorphology and self-cleaning performance of the wing surfaces demonstrate remarkable anisotropism. The special complex wettability ascribes to a coupling effect of the material element and the structure element. In microdimension, the smaller the width and the bigger the spacing of the scale, the stronger the hydrophobicity of the wing surfaces. In nano-dimension, the smaller the height and the smaller the width and the bigger the spacing of the longitudinal ridge, the stronger the hydrophobicity of the wing surfaces. This work promotes our understanding of the hydrophobicity mechanism of bio-surfaces and may bring inspiration for biomimetic design and preparation of smart interfacial materials.展开更多
基金The project supported by the National Natural Science Foundation of China (50375151,50323007,10225209)the Chinese Academy of Sciences (KJCX-SW-L2)
文摘A novel super-hydrophobic stearic acid(STA)film with a water contact angle of 166° was prepared by chemical adsorption on aluminum wafer coated with polyethyleneimine(PEI)film. The micro-tribological behavior of the super-hydrophobic STA monolayer was compared with that of the polished and PEI-coated Al surfaces.The effect of relative humidity on the adhesion and friction was investigated as well.It was found that the STA monolayer showed decreased friction,while the adhesive force was greatly decreased by increasing the surface roughness of the Al wafer to reduce the contact area between the atomic force microscope(AFM)tip and the sample surface to be tested.Thus the friction and adhesion of the Al wafer was effectively decreased by generating the STA monolayer, which indicated that it could be feasible and rational to prepare a surface with good adhesion resistance and lubricity by properly controlling the surface morphology and the chemical composition.Both the adhesion and friction decreased as the relative humidity was lowered from 65% to 10%,though the decrease extent became insignificant for the STA monolayer.
基金supported by the National Natural Science Foundation of China(50875108)the Natural Science Foundation of Jilin Province,China(201115162)the Open Fundof Key Laboratory of Bionic Engineering of Ministry of Education,Jilin University(K201004)
文摘The microstructure, wettability and chemical composition of the butterfly wing surfaces were investigated by a scanning electron microscope, a contact angle meter and a Fourier transform infrared spectrometer. The micro/nano structural models for hydrophobicity of the butterfly wing surfaces were established on the basis of the Cassie equation. The hydrophobicity mechanisms were discussed from the perspective of biological coupling. The butterfly wing surfaces are composed of naturally hydrophobic material and possess micro/nano hierarchical structures, including primary structure （micrometric scales）, secondary structure （nano longitudinal ridges and lateral bridges） and tertiary structure （nano stripes）. The wing surfaces exhibit high hydrophobicity （contact angle 138°-157°） and low adhesion （sliding angle 1°-3°）. The micromorphology and self-cleaning performance of the wing surfaces demonstrate remarkable anisotropism. The special complex wettability ascribes to a coupling effect of the material element and the structure element. In microdimension, the smaller the width and the bigger the spacing of the scale, the stronger the hydrophobicity of the wing surfaces. In nano-dimension, the smaller the height and the smaller the width and the bigger the spacing of the longitudinal ridge, the stronger the hydrophobicity of the wing surfaces. This work promotes our understanding of the hydrophobicity mechanism of bio-surfaces and may bring inspiration for biomimetic design and preparation of smart interfacial materials.
