Study On The Modification Of Graphene Oxide And Its Application In Waterborne Polyurethane Coatings

Because of its large sheet structure,graphene oxide has aexcellent blocking effect of corrosive substances,so graphene oxide has great application prospects in the field of anticorrosive coatings.However,due to the dispersion problem of graphene oxide in waterborne coatings,there are still some limitations of the application in coatings.The purpose of this research is to prepare a composite coating of modified graphene oxide and water-based coatings.The research contents mainly include the following two aspects:1.Graphene oxide is modified chemically to control the dispersibility of graphene oxide in waterborne polyurethane,and further prepare a composite coating of graphene oxide and waterborne polyurethane.In this part,?-(2,3-epoxypropoxy)propyltrimethoxysilane(KH560)functionalized nano-silica is first prepared to modify graphene oxide.Since the hydrophobicity of the functionalized nano-silica can be changed by adjusting the addition amount of KH560,the hydrophobicity of the modified graphene oxide can be indirectly adjusted without changing the properties of the graphene oxide.Furthermore,the hydrophobicity of graphene oxide is the key factor for the stable dispersion of graphene oxide in aqueous systems.Adjusting the addition amount of KH560 can effectively affect the dispersion of graphene oxide in waterborne polyurethane system.In addition,this method of regulating graphene oxide properties by preparing assisting "bridges"(like the functionalized nanosilica)provides a new idea for modification and future applications of graphene oxide.2.Properties of graphene oxide and waterborne polyurethane composite coatings were studied.In this part of research work,we tested the electrochemical impedance and polarization curves of the composite coatings through electrochemical workstation to characterize the corrosion resistance of the composite coating.The study results show that the relatively hydrophobicly modified graphene oxide has good corrosion resistance,while the relatively hydrophilic graphene oxide has poor corrosion resistance,and the excessively hydrophobic graphene oxide also decreases its corrosion resistance due to the decrease in dispersibility.Therefore,the change of the amount of KH560 also plays an important role in regulating the anticorrosive performance of composite coatings.By adjusting the amount of KH560 added,it is easy to find the balance between the dispersibility and corrosion resistance of graphene oxide.At the same time,the amount of graphene oxide can also affect the corrosion resistance of the coating.In addition,we also characterize the mechanical properties,wear resistance and other properties of the composite coating.The addition of graphene oxide can significantly improve the mechanical strength of the composite coating,but decreases the toughness of the corresponding composite coating.At the same time,the addition of graphene oxide also has a positive impact on the wear resistance of the composite coating.On the other hand,all the raw materials used in this subject are from industrial products,and the prepared water-based coatings are environmentally friendly.The active epoxy groups on the KH560 molecule can also provide reaction sites for the subsequent functionalization of coatings.These offer possibilities for the practice applications of the composite coatings.