The Regulation Of Nano-periodic Structure Substrate On The Growth Of Nano-droplets

The nucleation and growth mechanism of nanobubbles and nanodroplets on the interface is of great significance in the study of microfluidics and adsorption characteristics of hydrophobic surfaces.The nucleation and growth of nanodroplets on the surface microstructure are manifested in many basic and practical interface processes,such as the formation of dew,the condensation of water vapor in the cooling device,and the preparation of microdroplet functional structures.And it has broad potential application value in many fields such as fluid dynamics,surface chemistry,colloid chemistry,environment and life sciences,which has aroused great attention and attention from scientists.The study of interface nanodroplets is inseparable from the substrate,so the nature of the substrate is one of the key factors that influence the interface properties of nanodroplets.On the one hand,the formation,stability and interface morphology of droplets on different substrates may be different;on the other hand,the contact angles of nanodroplets obtained by different substrates may be different due to the properties of the substrate.However,the bases of each experimental group are relatively single,and the size and quantity of nanobubbles are poorly controllable and reproducible.Therefore,it is urgent to find a way to control the size and structure of nanodroplets by controlling the interface structure and properties of the substrate.The quantitative method to further study the basic physical properties of nanodroplets,formation mechanisms and stability mechanisms and other key issues.In the past 20 years,the use of atomic force microscopy(AFM)and related colloidal probe technology has been well developed,and Ducker et al.The role of hydrophobic and DLVO in the surface interaction of air bubbles was studied.Recently,Dagastine et al.presented a dynamic force-deformable drop between the two.Although most of the previous studies have focused on micro-droplets/ bubbles,the recent interaction between the nanoscale probes and the nano-scale droplets has attracted a wide interest in the basic fields and potential applications.Nano-droplets have been used as a system for ideal materials to study the nano-scale solid interactions near the water interface,and are also considered to be a theoretical simulation of nanobubbles.nano-droplets can be easily controlled to use the latest solvent-exchange preparation method as compared to nanobubbles,which enable us to systematically study their interface properties and to make the wetting theory reduced to nano-scale,which is also the basis for their diverse applications.Some important work has been completed.For example,atomic force microscopy measurements show that the deformation of the AFM probe on the droplet is like a simple Hookan spring,similar to a similar experiment for tiny droplets or bubbles.Several reports show a linear or near linear relationship between the interfacial tension and the drop stiffness.More interestingly,Munz et al.found a negative correlation between the measured stiffness and the droplet size.Understanding these phenomena requires accurate measurement and quantitative analysis.However,unlike the micronized droplets,it is difficult to measure the interaction between the droplet and the AFM probe accurately and quantitatively.Most of the previous studies were fairly qualitative and only preliminary information was obtained.In order to fully understand the interaction between the nano-droplet and the nano-probe,the quantitative research on the system needs to be carried out on the basis of accurate measurement.Based on the above-mentioned objects,the preparation of different hydrophobic substrates and the use of advanced micro-nano-processing technology,an electron beam lithography(EBL)direct-write technique,were used to prepare the nano-structure substrates with different cycles.Nano-droplets are produced on the substrate by an alcohol-water-replacement method,and the adsorption behavior and the interfacial properties of the nano-droplets on the periodic structure substrate are found by an advanced nano-observation technique,an Atomic Force Microscope(AFM)technology,The nano-droplets are mainly adsorbed on the hydrophobic region on the periodic structure and are limited by the size of the hydrophobic structure and further cause the change of the contact angle.