Preparation Of Superhydrophilic Coatings And Gradient Wettability Coating With Organic-inorganic Hybrid Materials

Organic-inorganic hybrid material is a new type composite, in which organiccomponents bind to inorganic components via some method. Not only does this kind materialhave good properties of organic and inorganic components, but also it has special propertiesoutside of organic and inorganic components. So it can be widely used in many fields. Phaseseparation is often found in the process of organic-inorganic hybrid materials preparation,which will affect greatly on the hybrid materials properties. Therefore, how to prepare andapply stable organic-inorganic hybrid materials is the main topic of this thesis.Organic-inorganic hybrid materials have been prepared with TEOS as inorganicprecursor, AA as organic precursor, and simultaneously loading with silicon coupling agentKH-570, the superhydrophilic coatings were prepared by solvent replacement and pH control.The effects of amount of tetraethyl or thosilicate (TEOS) and coupling agent KH-570, and pHon the hydrophilicity and water dissolution rate of the coatings were studied. The results showthat the coating prepared with TEOS70wt%and KH-5703wt%at pH7has a water contactangle of3°in early period, which is up to the demand of superhydrophilicity. The watercontact angle of the coating becomes11.7°after dry and wet cycles for30times. The waterdissolution rate of the coating is16%after immersing in water for100h without thephenomenon of bubble, blushing or chalkiness. The coating features an adhesion strength of0grade and a pencil hardness of7H, and does not tarnish at200°C for1h. And there are nolayer phenomenon in the superhydrophilic coatings after three months storage.The coating surface with a gradient wettability was prepared by slowly addinghexamethoxy methyl melamine (HMMM) and Fluorinated acrylate polymers orderly intoorganic-inorganic hybrid hydrophilic polymer while lifting the microslide substrate with acertain speed. After curing under high temperature, coating surface with a gradient wettabilitywas prepared. The effects of the mass ratio of TEOS/(TEOS+AA), the dosage of HMMM anddifferent Fluorinated acrylate polymers on gradient surfaces were studied. When the massratio of TEOS/(TEOS+AA) was inferior to0.3, the starting contact angle is about12°. Thecontact angle range of the continuous gradient coating is about12°to85°When the dosage ofHMMM was about20%and Fluorinated acrylate polymers with10%hexafluorobutyl acrylate was about20%of the organic-inorganic hybrid hydrophilic polymer, or Fluorinatedacrylate polymers with3%2-(Perfluoroalkyl)ethyl methacrylate was about10%. The contactangle range of the step-change gradient coating is about21°-51°-85°by adding4%,11%and5%curing agent, and20%fluro-contained acrylic polymer orderly.