3.1 modification of acrylateThe preparation methods of acrylate modified waterborne polyurethane are as follows:PA and PU are directly blended physically;(2) the crosslinking agent is added to form polyurethane - acrylate blend composite emulsion;(3) polyurethane emulsion as the seed emulsion, acrylate emulsion polymerization, the formation of a core-shell structure of PUA composite emulsion;(4) the two emulsions permeate each other with molecular linearity, and then react to form the PUA composite emulsion of polymer interpenetrating network;(5) graft copolymerization.3.2 modification of epoxy resinThe traditional waterborne polyurethane molecular chain contains ionic groups, and the molecular chain is a linear structure, rarely crosslinked branching, resulting in poor chemical resistance and water resistance of the film. Therefore, it can be modified by epoxy resin. There are two main preparation methods of epoxy modified waterborne polyurethane: mechanical blending and copolymerization. In blending, there is no chemical bond between epoxy and polyurethane.3.3 modification of organic fluorineDue to the small atomic radius of fluorine, strong electronegativity and high bond energy of carbon and fluorine, fluoropolymer emulsions containing fluoroalkyl side chains were introduced into the main chain of polymer molecules, and the latex membrane had outstanding surface properties on the basis of maintaining the original bulk properties. Since the fluorine-containing side chains are oriented outward and oriented, the main chains and internal molecules can be shielded and protected, which effectively improves the low surface energy, lubricity, chemical resistance, hydrophobicity, anti-fouling and good biocompatibility of polymer coatings.