The Preparation And Properties Of Superhydrophobic Organosilicon Composite Coatings

Superhydrophobic surfaces have important application value in self-cleaning,anti-corrosion,antifouling,drag reduction,oil-water separation and other fields.Inspired by the“lotus effect”,there are mainly two methods to prepare the superhydrophobic surfaces:modification of a rough surface using low-surface-energy components or fabrication of micro/nano-structures on a low-energy surface.In this study,starting with the construction of surface roughness,Stober method and emulsion polymerization method were used to prepare a superhydrophobic coatings with hierarchical micro-nano structures like the surface of lotus leaf.SiO₂ nanoparticles with controllable particle size were prepared by Stober method,and the influence of processing parameters on the particle size of SiO₂ nanoparticles was investigated.SiO₂ nanoparticles with particle size of 450 nm and 100 nm were modified with methyltriethoxysilane?MTES?,phenyltriethoxysilane?PhTMS?and octyl triethoxy silane?OTES?,respectively,and the modification process was study.The effect of the hydrophobicity modification was characterized by contact angle measurement.The surface group of the coating was analyzed by infrared spectrum.The results showed that the hydrophobicity modification effect of OTES was the best.The contact angle of the coating was up to 151°when the dosage of OTES was 0.03 mol and the degree of hydrolysis was 80%.The scanning electron microscope?SEM?images showed that the superhydrophobic coatings prepared by this method possess surfaces with hierarchical micro-nano structures,which is very similar to the surface of the lotus leaves.Therefore,the coatings showed great superhydrophobic effect.Superhydrophobic polymethylphenylsiloxane?PMPSQ?nanoparticles were synthesized by emulsion polymerization using MTES and PhTMS as the silicon source,and the superhydrophobic coatings were prepared with the PMPSQ nanoparticles.The effects of silicon source,emulsifier type and dosage,catalyst type and dosage on the particle size,hydrophobicity and storage stability of PMPSQ particles were studied,and the properties of the coatings were tested.The results showed that the optimum emulsifier was the twelve alkylbenzene sulfonate?SDBS?.The optimum catalyst was KOH.The optimum molar ratio of MTES and PhTMS was 1:1.By regulating the dosage of SDBS,KOH and silicon source,the particle size of 1?m and 200 nm were prepared respectively.To improve the mechanical stability of the coatings,the organosilicon binder was synthesized by acid catalyzed hydrolysis with MTES and PhTMS as the silicon source.The binder formed the Si-O-Si network structure between the coatings and the substrates,thus improving the adhesion of the coatings.The small particles were combined with the surface of the larger particles,forming strawberry like hierarchical micro-nano structures,endowing the coatings with excellent hydrophobicity and self-cleaning properties.The effect of the dipping number on the hydrophobicity and mechanical stability of the coatings was studied.When the the dipping number was 3,the coatings could remain superhydrophobic after 20 mechanical stability tests.In addition,the PMPSQ superhydrophobic coatings showed good thermal stability.The superhydrophobic properties of the coatings could remain after heat treatment at 400?in air for 24 h.