NMR AND ELECTRON-MICROSCOPIC INVESTIGATION OF POLYMERIZED COATINGS PREPARED FROM METHACRYLATE-FUNCTIONALIZED SILICA IN AN ACRYLIC MONOMER MATRIX

Coating formulations comprised of ethacryloxy)propyl]trimethoxysilane- functionalized colloidal silica in hexanediol diacrylate can exhibit t wo problems that are detrimental to their application. Higher viscosit y, which hinders ease of application, has been found by transmission e lectron microscopy (TEM) to arise primarily from the presence of agglo merated colloidal silica. Gel formation also results in higher viscosi ty of the formulation. TEM and solid-state C-13 and Si-29 NMR spectros copy showed that gelation was due to polymerization of the acrylates, with reaction at the carbon-carbon double bond of the methacrylate mor e prevalent than reaction of the acrylate functionality.