Anti-scratch and adhesion properties of photo-curable polymer/clay nanocomposite coatings based on methacrylate monomers

Different types of polymer/clay nanocomposite were prepared and evaluated for their application as hard and anti-scratch coating materials. Photo-curable nanocomposites, based on 2,2-bis[4-(methacryloxypropoxy)-phenyl]propane (Bis-GMA (2,2-bis[4-(methacryloxypropoxy)-phenyl]propane)) and tri (ethylene glycol)dimethacrylate (TEGDMA (tri(ethylene glycol)dimethacrylate)) (50/50 wt%) were prepared using three types of clay at different loading levels. The adhesion properties and scratch resistivity of the coatings on polymethymethacrylate slabs were investigated. The results were correlated with the clay dispersion state, determined by a transmission electron microscopy, X-ray diffraction and the surface morphology by atomic force microscopy. It was concluded that exfoliation or intercalation plays an important role, primarily in surface roughness, which in turn affects adhesion by changing the characteristics of the coating-substrate interface. The highest scratch resistivity with appropriate adhesion quality was obtained for a sample containing 1 wt% of more compatible clay, Cloisite® 30B in the nanocomposite resin mixture.