Nano-Structured Polymer Coatings for Ultraviolet Protection
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Nano-Structured Polymer Coatings for Ultraviolet Protection Phaneshwar Katangur, Steven B Warner, Prabir K Patra, Yong K Kim, Shamal K Mhetre, Autumn Dhanote. Department of Textile Science, University of Massachusetts Dartmouth, 285-Old Westport road, N. Dartmouth, MA 02747, USA. ABSTRACT Polymer materials such as Kevlar that are susceptible to UV degradation may be protected by appropriate coatings. We are using zinc oxide and titanium dioxide nanoparticles with an average particle size ranging from 25 to 70 nm. Five weight percent nanoparticles were dispersed in acrylic coatings, the dispersion is assisted by addition of a non-ionic surfactant, mechanical stirring and ultrasonication. The UV protective mechanism of nanoparticleembedded coatings is theoretically explained using Mie theory. We estimated the minimum thickness of a 5 weight % nanoparticle-embedded coatings that is required to prevent the UV radiation from reaching the base of the substrate. Results obtained from nanoparticle-embedded acrylic-coated Kevlar fabric and neat acrylic-coated Kevlar fabric after exposure to UV radiation in QUV weatherometer show that the nanoparticle coating offers protection. UV-visible spectroscopy was used to obtain quantitative results. INTRODUCTION Ultraviolet radiation, ranging from 280 - 400 nm, is about 5% of the total light reaching the earth’s surface [1]. The radiation has detrimental effects on synthetic polymers as well as on human skin, a natural polymer [1]. Polymers are protected from photo-degradation by using various chemical and physical UV absorbers [2]. Physical absorbers like TiO2 and ZnO pigments of micron size have been used for decades in coating formulations, but they require a large filler content to instill UV protection [3, 5]. Cosmetic products were some of the first commercial products to incorporate nanotechnology, i.e., nanoscale powders (
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