Preparation And Properties Of Modified Polyurethane Nanocomposite Coatings

At present,coatings with hydrophobic and antifouling properties are usually used to protect industrial substrates or protect building facilities from biological pollution and chemical corrosion.Because of its simple preparation process,various application scenarios and low cost,it is widely used in different industrialization.Polyurethane is widely used in hydrophobic and antifouling coatings.However,with the development of social industry,there are some special corrosive environments in practical application.For example,seawater will be corroded by a variety of biological and mineral salts,which will lead to the falling off of hull protective coating and loss of protective effect.Therefore,a single polyurethane coating can not meet these complex environments,durable Corrosion resistance and antibacterial properties have certain deficiencies.Therefore,the research significance of preparing a multifunctional composite coating with wear resistance,corrosion resistance and antibacterial is reflected.Polyurethane has certain corrosion resistance,but it has insufficient corrosion resistance in the face of complex corrosion environment.The reason is that some nano pore defects and folds will appear in the process of polyurethane formation,and the corrosion solution will cause corrosion to the substrate through these defects.One of the ways to solve these defects is to fill with nanoparticles,which can be used to make up for the defects and provide different functional properties.After they are combined with each other,they can form composite coatings required in industrial applications.In this paper,through the combination of nanoparticles and polyurethane,the durability composite coatings with different functions are formed.The composite coatings are analyzed by various test and characterization methods,the compatibility between nanoparticles and polyurethane is solved,and the coating with the best proportion is tested.The main research contents are as follows:（1）Octadecyl trichlorosilane（OTS）was grafted onto fumed silica（SiO₂）by one-step method and modified into hydrophobic SiO₂.Then hydrophobic SiO₂in different proportions was mixed with polyurethane（PU）by mechanical mixing to form a durable hydrophobic SiO₂/PU composite coating.In the composite coating,PU is used as a crosslinking agent to ensure mechanical durability,and hydrophobic SiO₂provides superhydrophobic effect for the composite coating.The composite coating with the best proportion of hydrophobic SiO₂and PU is selected through SEM,UV and contact angle,and the practical application effect of the composite coating is shown.However,the composite coating can only ensure good hydrophobic self-cleaning and mechanical durability in daily application,and there are still deficiencies in the application in special corrosive environment.（2）In order to ensure that the coating can have more stable mechanical durability in chemical corrosion environment,we chose PU as the main body,introduced functional nano particle carbon nitride（g-C₃N₄）with two-dimensional lamellar structure to make up for the pore defects of PU,and prepared a modified g-C₃N₄/PU composite coating with wear and corrosion resistance.Melamine was calcined into g-C₃N₄by thermal polymerization,and then modified by modifier OTS to destroy the van der Waals force between the layers to increase the dispersion of g-C₃N₄.Finally,the modified g-C₃N₄was doped into PU by blending to form a modified g-C₃N₄/PU composite coating.G-C₃N₄has a two-dimensional lamellar structure,which can make up for the pore defects and folds in PU,increase the density of the composite coating,and prevent the corrosion solution from corroding the substrate through the defects.The mechanical properties of the modified g-C₃N₄/PU composite coating are significantly improved compared with PU.（3）In the complex environment such as seawater,the damage of microorganisms and mineral salts to the substrate can not be ignored.Therefore,on the basis of the second system,a layer of antibacterial metal oxide cuprous oxide（Cu₂O）was grown on the surface of modified g-C₃N₄,and the composite modified nanocomposite particles were blended with Pu to form a modified g-C₃N₄/Cu₂O/PU composite coating with anti-corrosion and antibacterial.Finally,through antibacterial,electrochemical The modified g-C₃N₄/Cu₂O/PU composite coating with the best performance was selected by SEM and other tests,and the performance effect of the composite coating was calculated.