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Pigment and Nanofiller Photoreactivity Database



Stephanie S. Watson, I-Hsiang Tseng, Tarek Marray, Bastien T. Pellegrin


The service life and durability of nanocomposites that contain fillers are affected by photocatalytic properties of these fillers, particularly narrow band gap metal oxides (NBMOs) such as titanium dioxide (TiO2). When illuminated with ultraviolet (UV) radiation, NBMOs produce electrons and other species that are capable of causing rapid degradation of organic materials with which they contact. Electrons and holes (positively charged species) migrate to the surface and react with species to generate various free radicals. Measurement science tools for characterizing TiO2 photoreactivity using electron paramagnetic resonance (EPR) methods have been developed by the Engineering Laboratory (EL) at the National Institute of Standards and Technology (NIST) and a linkage between EPR measurements and current industrial methods has been established. EPR, which measures unpaired electron species such as free radicals, was used to elucidate the mechanisms involved in the UV response of TiO2. EPR analyses were completed on a set of TiO2 specimens in the solid state (dry powder) as well as in liquid suspensions with spin traps. Since different spin traps target specific radical species, the use of a carefully selected set of EPR spin traps allows for a comprehensive understanding of specific radicals generated for a given material. Correlations were drawn between specific particle characteristics (size and size distribution, surface physical and chemical properties, crystal phase, etc.) and the nature/quantity of free radicals generated. A database of TiO2 photoreactivity values and other data measured via the EPR methods and industrial assays has been compiled and will be accessed through a searchable software database in the NIST Standard Reference Database program ( The database will provide fundamental photoreactivity data that can be used for product selection and development purposes to enable more reliable assessments of
Journal of Coatings Technology


pigment, nanoparticle, photoreactivity, EPR, free radical


Watson, S. , Tseng, I. , Marray, T. and Pellegrin, B. (2012), Pigment and Nanofiller Photoreactivity Database, Journal of Coatings Technology (Accessed May 20, 2024)


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Created July 2, 2012, Updated February 19, 2017