Biomimetic Construction And Characterization Of The Superhydrophobic Surface Of Wood Adhered By Polydopamine

Wood is a kind of natural biomass porous composite material,which has alarge number of hydrophilic groups such as hydroxyl groups on its surface so that has a strong sensitivity to water,and can absorb and store the external water,resulting in wood deformation,mildew,decay and other defects.The superhydrophobic wood can effectively improve waterproof,mildew proof and self-cleaning properties,and which has important practical significance.Inspired by the"lotus leaf effect"micro nano double scale surface structure in nature,the superhydrophobic wood of micro nano structure of the surface can be realized by loading inorganic nanoparticles.Therefore,improving the interface stability between inorganic nanoparticles and wood is the key problem to be solved in the preparation of superhydrophobic wood.In this study,based on the strong adhesiveness and more reactive sites of PDA,a stable micro nano structure was designed and constructed on the wood surface.The results are as follows:?1?Based on epoxy/amino system design super hydrophobic wood surface with high stabilityThe surface structure of superhydrophobic wood was designed by the PDA,because of it have a lot of active groups such as amino group and phenolic hydroxyl group.A layer of PDA coating was deposited on the surface of wood by self polymerization of dopamine solution.Secondly,nano silica?SiO₂?was fixed on the surface of wood in the form of covalent bond under the joint action of silane coupling agent?-aminopropyl triethoxysilane?KH550?and epoxy crosslinker glycol diglycidyl ether?edge?Super hydrophobic wood was prepared by low surface energy treatment.The results show that the water contact angle of wood surface is 156.6°,rolling angle is 4.7°,and the surface of super hydrophobic wood has obvious rough structure.Nano-SiO2 is fixed on the surface of wood by the reaction of PDA with silane coupling agent and cross-linking agent through amino and epoxy,and the surface stability and chemical stability of super hydrophobic wood surface are improved.?2?Preparation of super hydrophobic wood surface by one-step/two-step methodIn the process of self polymerization of PDA,the addition of silane coupling agent 3-Mercaptopropyltriethoxysilane?KH580?and nano aluminum oxide?Al₂O₃??one-step?or the Al₂O₃ of grafted with KH580?two-step?.The addition reaction of Schiff base and Michael occurs between PDA or its derivatives and silane coupling agent.The Al₂O₃ was firmly fixed in the wood through covalent/noncovalent action on the surface,a stable micro nano rough structure was constructed to prepare superhydrophobic wood surface.The results showed that the surface of wood prepared by one-step method presented honeycomb structure with a contact angle of 155.2°;the surface of wood prepared by two-step method presented layered structure with a contact angle of 152.9°.The surface of superhydrophobic wood prepared by one-step method had a more reasonable micro nano roughness.XPS and TGA analysis showed that kh580had a covalent effect with PDA,so the wood showed good surface stability Sex and chemical stability.?3?The preparation of superhydrophobic wood by micronano roughness constructed with PDA etchingIn this study,two kinds of strong alkaline solutions?NaOH and SMS?were used to etch the PDA wood coating,which solved the problem of poor interface bonding between inorganic nanoparticles and wood.The water contact angle of the superhydrophobic wood was up to 157.4°.The results of SEM and AFM show that the peeling off of PDA in the strong alkaline environment is the whole peeling off behavior,and the obvious micro nano rough structure is formed.SMS hydrolyzes to form oligo or polymerized polysiloxane,which makes the superhydrophobic wood etched by SMS in the strong alkaline solution show higher roughness and contact angle.The superhydrophobic wood surface has high stability and superhydrophobic wood surface chemistry The stability test shows that the super hydrophobic surface shows good acid and alkali resistance and organic solvent resistance because of the removal of the polymer that PDA is easy to fall off in strong alkali environment..