Study On Wetting Function Regulation And Optimization Of Micro-nano Structure Surface By Femtosecond Laser

Surface wettability concerning on solid is a fundamental feature.The fabrication of micro-nano structures can effectively improve the surface wettability and the surface can play an important application value in industry and life.Different application will produce different requirements and variables.For example,anti-icing applications require hydrophobic surfaces to work in different temperature environments,and some applications such as water collection and oil-water separation require hydrophilic wettability surfaces to maintain stable hydrophilic properties for a long time.Therefore,it is necessary to study the wettability change by adjusting the environmental temperature and how to suppress the performance change of the hydrophilic.Based on the above new trend of wettability micronano structure surface research,this article is based on the femtosecond laser process micronano structure surface technology,for stainless steel materials widely used in industry,research that surface wettability was controlled by temperature and surface chemical composition changes.The detailed research content is as follows:1.Research on the temperature regulate surface wettability of the hydrophobic micronano structure.The femtosecond laser is used to prepare uniform columnar micro-nano structures on the surface of stainless steel,and then the surface is modified to superhydrophobic surface by silanization,and change the wettability via adjust temperature is further studied.The experimental results show that the contact angle increases with the increase of surface temperature,and the surface become more hydrophobic.This reason is that the increase of temperature result in the decrease of surface energy.When the temperature rises to 80 °C,the droplets evaporate significantly.With the decrease in volume,the contact angle is stable during the initial stage of the evaporation process,and the silanization causes chemical heterogeneity bring about the droplet changes its state during the evaporation process.In terms of adaptability of temperature environment,compared to the silicone grease heat treatment method,the silanization treatment method represent better act,and the superhydrophobic firmness is still maintained after immersion in boiling water for two hours.2.Research on the influence and optimization of chemical treatment to surface wettability.Two typical micro-nano structure surfaces by femtosecond laser and a comparative study are carried out on the change rule and mechanism of micro-nano structure surface wettability with time to sodium hydroxide solution treatment and without chemical treatment,use the X-ray photoelectron spectroscopy to find the changes in chemical composition of the hydrophilic surface.Experiments have found that the superhydrophilic surface reduce the surface energy by absorb organic matte when surface stored in the air,it affects the stability of the hydrophilicity and slowly alter to hydrophobicity.The transformation mechanism can be determined by surface composition analysis that it is the sorption of organic matter.Further,the soaking method of sodium hydroxide solution can realize the transformation of the wetting mechanism(conversion to oxygen replacement),and also effectively reduce the rate of the wetting transformation.This experiment shows that the method of sodium hydroxide solution treatment can inhibit the change of the wettability.On the other hand,by comparing the morphology of different structures,it is found that the micro-scale structure surface can impactful maintain the hydrophilic properties by increasing the surface roughness.Therefore,adjusting the surface roughness also helps to suppress the change in its wettability.It provides an effective method to maintain the surface hydrophilicity from the two aspects of structure and chemical composition,which has certain significance for the hydrophilic surface application.