Study On The Hydrophobic And Frictional Properties Of "Solid-liquid" Interface Based On Fe₃O₄ Nanoparticles

In recent decades,with the rapid development of science and technology,the number of industries related to surface chemistry and physics has increased sharply.The research on solid-liquid interface phenomenon and the further exploration of application fields has also become the focus in various fields.The solid-liquid interface can be affected by adjusting the properties of solids and liquids,or changing the external environment,moreover,the behavior and function of the whole system is affected.In this paper,the superhydrophobic and frictional properties of liquid lubricants on solid surfaces are used to guide the application and study the case.Through the intervention of nanoparticles,the"solid-liquid"interface is reconstructed to effectively regulate the superhydrophobic and anti-friction wear resistance of solid interface.The work of this thesis is carried out from the following content:1.The interface between graphene and water:The superhydrophobic coating with micro-nano structure was prepared by using the Fe₃O₄ nanoparticles to enhance the interlaminar bonding strength of graphene micrometers.By adding Fe₃O₄ nanoparticles with different contents and using polydimethylsiloxane as binder,the superhydrophobic micro-nano structure surface with certain mechanical strength was finally formed.The added Fe₃O₄ nanoparticles were compounded with graphene micron sheet layer,and Fe₃O₄/graphene micronanometer sheet was formed by Fe-O-C chemical bond.It was found by Raman spectroscopy that the characteristic G peak of graphene at this time was blue shifted,which indicated that Fe₃O₄ nanoparticles significantly enhanced the interaction between graphene micron sheet layers.Further study found that when the mass ratio between Fe₃O₄ nanoparticles and graphene was 1.8:0.1,the composite coating had the best hydrophobic performance and mechanical strength:the static Contact Angle(CA)was 164°,the rolling Angle was<2°.The excellent and stable superhydrophobic performance can be maintained under severe conditions such as simulated seawater,the strong impact of water column,acid and alkaline environment,high and low temperature.2.The interface between silicon and ionic liquid(IL):Carbon-coated Fe₃O₄nanoparticles(Fe₃O₄@C)were used to lock the liquid lubricant—the IL(1-butyl-3-methylimidazole hexafluorophosphate,[BMIM][PF₆])on the surface of solid silicon to improve its bearing capacity and corresponding anti-wear lubrication capacity.Especially when the addition amount of Fe₃O₄@C in the IL was 0.001 wt%,the surface lubrication performance was the best,and the friction coefficient of Fe₃O₄@C was reduced by about 88%compared with pure IL.In order to quantify the effect of Fe₃O₄@C on strengthening ionic liquid-silicon substrate interaction,Fe₃O₄@C colloidal AFM tip was further formed by modifying Fe₃O₄@C core-shell nanoparticles onto AFM probes.The adhesion force between Fe₃O₄@C and the silicon substrate was measured as 198 n N,which is far stronger than that between the pure IL and silicon substrate(10 n N).Fe₃O₄@C particles were added to the IL and exerted‘normal pin-force'and thus anchor the IL film strongly onto surfaces,resulting in stable and self-standing IL films even at high loads,showing an excellent anti-wear ability.An obvious blue shift of the IL anion[PF₆]^-characteristic band in ATR-FTIR,confirmed the strengthened interaction between the IL and silicon substrate.