Study On Liquid-Liquid Interface Spread And Regulation Of Multi-Droplet Wetting Response

Liquid-liquid interface spreading has a wide range of applications in many engineering fields and biochemical processes.The controllable surface can realize the adjustment of the infiltration state under stimulation,which is of great significance in nanofluidics,medical field,material science and other aspects.Fluid diffusion and film formation phenomena are very common,such as lava flow,engine fuel delivery,fertilization application in agricultural production,paint flow,deformation of liquid metals,surfactant substitution therapy,etc.The use of surfactants for wettability control has always been a research hotspot,and the interface condition of the system is changed by surfactants,thereby affecting its spreading,wetting and adhesion.Therefore,the research on the surface infiltration phenomenon of active agent solution has received extensive attention,and has been a hot spot in physics,mechanics,biology and other fields.The motion of the three-phase contact line has self-similarity,and the spreading radius and the spreading time are proportional to the power exponential relationship of R～t~nand the dynamic mechanism of spreading during infiltration can be reflected through the power index n.In this paper,the liquid-liquid interface infiltration problem with surfactant solution as base liquid was studied from the macro scale through experiments and data fitting methods,and the internal mechanism of interface monolayer active agent molecules in the process of dynamic wettability of liquid was analyzed.Different from the spontaneous drive spreading system in previous studies,this paper changes the droplet spreading state by pulling and pressing the driving liquid level,and establishes an infiltration experimental system composed of n-hexadecane as the driven droplet and sodium dodecyl sulfate solution as the base solution,which realizes the dynamic response of the infiltration state.The n-hexadecane droplets are stably spread on the liquid surface between the movable baffles,and the dynamic wetting response of n-hexadecane is realized through the tensile-compressive movement of the baffles.Through preliminary exploration,we select a fixed concentration of surfactant solution to match the optimal n-hexadecane spreading state.The experiment found that when the baffle stretched outward,the n-cetane droplets spread outward,and when the baffle was squeezed inward,the droplets shrink inward.The analysis showed that the movement of the baffle changed the interfacial distribution density of surfactant molecules around the droplet,which changed the spreading coefficient and changed the spreading state of the droplet.In this paper,it is not limited to a single droplet,but also carries out the tensile-pressure driving response experiment on multiple droplets,and realizes the synergy of the infiltration state of two droplets and three droplets.Experiments also show that the dynamic wetting response speed of single droplets or multiple droplets is positively correlated with the baffle movement speed.The work of this paper gives new ideas and means for liquid interface manipulation,which is expected to be applied in interface assembly technology.