Experimental Study On The Effect Of Surface Microstructure And Temperature Coupling On Interfacial Wettability

Interfacial wettability is one of the most important basic properties of solid surfaces.Solid-liquid interface wettability would be effected by its solid surface micro-structure and distribution,surface energy,three-phase contact line,solid-liquid contact area fraction,and even droplet size.In this paper,the 4-shapes patterns were first designed on a glass mask,and then the micro-pillar structure were fabricated on the surface of the si.licon wafer by micro-fabrication processing technology.Then,the surface micro-structure on thesilicon wafer was characterized by laser confocal microscopy,and then the contact angle of the micro-structures with different densities and shapes on the silicon wafer were measured at room temperature.Using single variable analysis,the experimental data of micro--structured surface's contact angles with different space between micro-pillars,different shapes and different heights are analyzed.It was obtained that the hydrophilic,hydrophobic and super-hydrophobic wetting state of the interface can be controlled by controlling the micro-pillar spacing b;For the surface contact angle of the micro-pillar,when the micro-pillar parameter b/h is closest to 2.5,the surface contact angles of the micro-pillar were match the maximum,and the surfaces were the superhydrophobic state.In order to study the effect of temperature on superhydrophobicity,the contact angles at different temperatures were measured,and combined with experimental data,it was obtained that in the temperature changing environment,when the temperature T=60??90? stage,the wetting stagement on some microstructured surfaces were transited from Cassie-Baxter stage to Wenzel stage,the surface losed the super-hydrophobicityIn the temperature-changing environment,the main reason for the transition of wetting state was that as the temperature increasing,the surface tension of the droplet decreased,which leads to the weakening of the self-shrinking ability of the droplet surface,and when the spacing between the micro-pillars was increased,it would cause a smaller solid-liquid contact area;And the gravity pressure on unit area will be increased with the contact area decreased.The most intuitive reason for the CA decrease was that the micro-pillars pierced the droplets,resulting in a change in the wet state,we also found that this reason result in our test experiment.