Investigation Of Superamphiphobic Surface Constructed By Large-Sized SiO₂

Inspired by the non-wettability biological surfaces in nature,superamphiphobic material has attracted extensive attention from researchers because of its promising applications.Since the superamphiphobic porformance of a solid surface depend on the microstructure and chemical composition of the surface,researchers mainly control the amphiphobicity by changing the topography and surface tension of the solid surface.Re-entrant geometries can effectively trap air-pockets beneath coating surface,prevent the penetration of low-surface-tension organic liquids,and achieve superamphiphobicity.However,the creation of re-entrant geometries through particle-based spray-coating remains a challenge.In the past decades,various studies have focused on the preparation of superamphiphobic coatings using ultrafine nanoparticles(10–15 nm)by conventional spray-coating method.In this work,we aim at fabricate a spray-coated superamphiphobic surface by large particles with re-entrant geometries.The study systematically investigated the surfaces with different morphologies and different wettability,which obtained using particles of different sizes and morphologies(i.e.,smooth,micro,nano,and micro/nanostructures)by different coating methods.The main contents are as follows:1.The SiO₂ particles with smooth surface,the hydrothermal carbon spheres with uniform size(MDHTC),the solid particles with SiO₂ coated on the surface of the carbon spheres(C@SiO₂),and the hierarchically mono-dispersed hollow SiO₂ spheres(MDH-SiO₂)are deposited on glass slides by the colloidal template method and spray-coating method,respectively.All above coatings modified with the same low surface energy to made them with different amphiphobicity.The findings suggested that:Compared with the typical colloid template method,the surface obtained by the spray-coating method showed much greater roughness,which greatly enhanced the oleophobicity.Furthermore,only the MDH-SiO₂ coating prepared by the spray-coating method showed excellent superamphiphobicity,which was independent of the hollow sphere size.In addition,while maintaining the coating roughness,by applying C@SiO₂ as a reference sample,the important role of the hollow structure of MDH-SiO₂at the solid–liquid–air interface was confirmed.Nanosphere-surrounded hollow structures were shown to serve as a re-entrant structure,preventing the imbibition of the liquid,and finally leading to a stable Cassie state.Finally,it is confirmed that after the particles cover the substrate completely,the superamphiphobicity of the coating is independent with thickness.2.C@SiO₂ and MDH-SiO₂ were prepared into dense coatings by colloidal template method,respectively;C@SiO₂ and MDH-SiO₂ were prepared into random coatings by spraying-coating method,respectively.The air ratio in different coatings had be calculated successfully depend on the regular structure of C@SiO₂ and MDH-SiO₂,and the definition of contact angle in the Cassie-Baxter formula.What's more,we confirmed the influence of the air ratio in the coating on its double phobic performance:The greater the proportion of air in the coating,the better superamphiphobicity.3.Preparing mixed solutions of MDH-SiO₂ and?-Ethyl cyanoacrylate(?-ECA)with different proportions in acetone,and spray them on the same glass slides.After natural curing,modify them with the same low surface energy to prepare coatings with different robustness and amphiphobicity.Through the contact angle test and sandpaper abrasion test,it is found that the greater the proportion of?-ECA in the mixed solution,the better the robustness of the coating,the worst amphiphobicity of the coating.