Novel Hybrid Inorganic-Organic Abrasion-Resistant Coatings Prepared by a Sol-Gel Process

Novel abrasion-resistant coatings prepared by a sol-gel process have been developed and applied on the polymeric substrate Bisphenol A polycarbonate. In general, coatings utilize either 4,4′-diaminodiphenyl sulfone (DDS) or diethylenetriamine (DETA) that are then functionalized at their amine groups with 3-isocyanatopropyltriethoxysilane. Following functionalization, these coating materials are then spin coated onto bisphenol A polycarbonate sheet and cured. These reactants undergo a comparable sol-gel reaction similar to typical metal alkoxide chemistry, thereby producing an insoluble network material containing a good dispersion of the functionalized organic along with the hydrolyzed and condensed silicon alkoxide groups. The final coating is transparent and of a few microns in thickness. Following curing, an index of the abrasion resistance is assessed by an optical method, and the adhesion behavior of the coatings is investigated and quantified. It is demonstrated that these thin transparent coatings do provide considerable abrasion resistance over and above that of the uncoated polymeric substrate.