Multi-functional protective nanocomposite coatings of modified graphene and hexagonal boron nitride nanoparticles on transparent plastics
Nanocoating is the result of a coating application of nanomaterials to build a consistent network of molecules in a coating or paint to protect a surface. Graphene is an allotrope of carbon in the two dimensional form, that is on an atomic scale, has a hexagonal lattice with extraordinary physical and chemical properties. Application of graphene in the coating show excellent performances. By adding functionalized graphene into paints or coatings, they will absorb the harmful UV part of sunlight; prevent coating degradation, and the impact of the environmental factors on the coatings to enhance longevity and durability. Boron Nitride (BN) has a similar structure of carbon lattice and excellent thermal and chemical stability. Boron nitride nanocoating is a thermally insulating material for heat dissipation. In this study, graphene and hexagonal BN (h-BN) were modified with [3- (2-Aminoethylamino) propyl] trimethoxysilane and uniformly added into the polyurethane paint with different amounts, such as 0.1wt %, 0.2wt%, 0.4wt%, and 0.8wt% to increase hardness, and water resistance, and decrease UV degradation. The samples were characterized by using Fourier Transform Infrared Spectroscopy (FTIR), UV Vis, Scanning Electron Microscope (SEM), Water contact angle, and Differential Scanning Calorimetry (DSC). Nanocoatings with h-BN showed very good water contact angle and only a small decrease after the UV chamber with an average amount of 1.30 degree average. The thickness of the coatings was degraded with a small amount of .0007” average, but the surface coating didn’t change color after 20 days in UV chamber. Unlike h-BN coating, the coating with graphene was affected by the UV light with a color change from clear to yellowish, coating thicknesses degraded after 20 days UV chamber with the rate of 0.0038” average. The water contact angle also changed with a larger amount of 1.33 degree compared to the nanocomposite coatings of h-BN inclusions.
Thesis (M.S.)--Wichita State University, College of Engineering, Dept. of Mechanical Engineering