Amphiphobic Modification Of Al And Zn Metal Surfaces And Their Self-cleaning Properties

Super-amphiphobic surfaces with self-cleaning property on common metalincluding Al and Zn substrates were fabricated by Au-assisted chemical wet etchingprocess, hydrothermal method to create surface micronano-structure, followed by CVDtechnique to reduce surface free energy. Such self-cleaning surfaces were also preparedby one-step spraying coating on Al and Zn metal substrates. Also, new type ofself-cleaning slippery pre-suffused surfaces was prepared on Si substrates. The resultsshowed that:(1) A disorderly and nanoscale fluffy surface microstructure was constructed on Alsubstrates by chemical wet etching process in which neutral KCl etchant was used.After treated by fluoroalkysilane (FAS), Al substrate surfaces were superhydrophobicand highly oleophobic, demonstrating excellent self-cleaning property. The as-preparedsurfaces display roll-off angles less than10°with water and testing oils and exhibitexcellent dynamic wettability.(2) ZnO nanorod thin film surfaces which were fabricated on Zn substrates weresuperhydrophilic and superoleophilic,displaying the static contact angle0°withwater.But after treated by fluoroalkysilane(FAS), the wettability of such surfaceschanged systematacially, from superhydrophilic and superoleophilic tosuper-hydrophobic and highly-oleophobic. The roll-off angles of water, glycerol andformamide on the as-prepared surfaces were less than10°, displaying excellentdynamic wettability. The roll-off angle of diethylene glycol was bigger，exhibiting baddynamic wettability.(3) The as-prepared coating surfaces which were highly hydrophobic andoleophobic were fabricated on Al substrates by sprayed method. Such surfaces had goodself-cleaning property. The roll-off angles of water and testing oils such as glycerol,formamide and diethylene glycol were less than12°, demonstrating good dynamicwettability. For hexadecane droplet, the static contact angle reached up to122°, but itpinned on coating surfaces and couldn’t roll off.(4) New type self-cleaning slippery pre-suffused surfaces was fabricated on Si substrates through Au-assisted wet chemical etching technique followed by surfacemodification with a fluorinated silane and subsequently pre-suffusing lubricant onto itssurfaces.Such surfaces had a excellent slip property and good self-cleaning property,which displayed sliding angles less than10°with all testing droplets(water andoil).Most importantly, Such surfaces displayed sliding angles no more than6.5°withhexadecane whose surface tension is only27.5mN/m.