{"374591":{"#nid":"374591","#data":{"type":"news","title":"Electrochromic polymers create broad color palette for sunglasses, windows","body":[{"value":"\u003Cp\u003EArtists, print designers and interior decorators have long had access to a broad palette of paint and ink colors for their work. Now, researchers have created a broad color palette of electrochromic polymers, materials that can be used for sunglasses, window tinting and other applications that rely on electrical current to produce color changes.\u003C\/p\u003E\u003Cp\u003EBy developing electrochromic polymer materials in a range of primary and secondary colors and combining them in specific blends, the researchers have covered the color spectrum \u2013 even creating four shades of brown, a particularly difficult color combination. The materials could be used to make sunglasses that change from tinted to clear in a matter of seconds, at the press of a button. Other uses could include window tinting, signage and even greeting cards that change color through the application of low-voltage electrical current.\u003C\/p\u003E\u003Cp\u003ESupported by BASF, the research is reported in the journal \u003Cem\u003EACS Applied Materials \u0026amp; Interfaces\u003C\/em\u003E. The research was done in the laboratory of John Reynolds, a professor in the School of Chemistry and Biochemisty and the School of Materials Science and Engineering at the Georgia Institute of Technology.\u003C\/p\u003E\u003Cp\u003E\u201cWe\u2019ve demonstrated the ability to create virtually any color we want by mixing different electrochromic polymers, just like mixing paint,\u201d said Anna \u00d6sterholm, a research scientist in Georgia Tech\u2019s School of Chemistry and Biochemistry and the paper\u2019s first author. \u201cUsing a simple coating method or even inkjet printing, we can create films that change color with the application of a voltage.\u201d\u003C\/p\u003E\u003Cp\u003EThe many colors that have been developed by Reynolds\u2019 group over the years include magenta, cyan, yellow, orange, blue and green polymers that can be dissolved in common solvents. In addition, blends of these polymer solutions can be predictably mixed to target specific colors.\u003C\/p\u003E\u003Cp\u003ETo demonstrate the capabilities, the researchers created brown lenses for sunglasses using a five-layer sandwich of materials, including a film of the electrochromic material, a charge storage layer and a UV-curable electrolyte, with a cathode and anode layer on either side.\u003C\/p\u003E\u003Cp\u003EThe lenses can be switched between a colored and colorless state by applying a brief pulse of electrical current and do not need a continuous power supply. To maintain the colorless state, a brief refresh pulse needs to be applied approximately every 30 minutes; however, the colored state can be stable for up to several days. The materials can switch from about 10 percent transmittance to 70 percent transmittance \u2013 and back \u2013 in a few seconds.\u003C\/p\u003E\u003Cp\u003EThe brown shades are created by combining cyan and yellow primary colors with orange and periwinkle-blue secondary colors.\u003C\/p\u003E\u003Cp\u003EPhotochromic sunglasses, which darken in response to light using a silver halide reaction, are already on the market. But many of these lenses respond to ultraviolet wavelengths that are filtered out by automobile windshields, require several minutes to transition \u2013 and can\u2019t be controlled by users. The passive switching time can be problematic for pilots, drivers, security officers or others who move quickly between light and dark environments.\u003C\/p\u003E\u003Cp\u003E\u201cIn contrast, by using electrochromic polymers, we can create devices that by pushing a button, can be converted from dark to clear,\u201d said \u00d6sterholm. \u201cThey are completely user-controlled, and it doesn\u2019t matter whether they are being used indoors or outdoors, in a vehicle or an aircraft.\u201d\u003C\/p\u003E\u003Cp\u003EThe electrochromic materials rely on a reduction-oxidation (redox) reaction triggered by the application of an electrical potential provided by a simple coin battery: a positive one volt causes the glasses to be clear, while a minus one volt switches to the color. \u201cEssentially, we are just charging and discharging the device, which is what causes the color change,\u201d explained Eric Shen, a postdoctoral fellow in the Georgia Tech School of Chemistry and Biochemistry.\u003C\/p\u003E\u003Cp\u003EThe electrochromic materials represent years of work by the Reynolds Laboratory to synthesize polymers whose repeat-unit structures provide the desired palette of colors. Because they can be dissolved in the same solvents, additional colors can be created by combining specific quantities of the primary and secondary colors.\u003C\/p\u003E\u003Cp\u003E\u201cAnything that you would want to have change color at the push of a button would be an application for these,\u201d said Shen. \u201cWe have shown that we can switch them on and off thousands of times, and that we can shine strong light on them without causing degradation of the color.\u201d\u003C\/p\u003E\u003Cp\u003EThe researchers have used simple spray and blade-coating techniques to create films of the colorful materials. They now are using ink-jet printing to create patterns and mix the polymers to create colors.\u003C\/p\u003E\u003Cp\u003E\u201cThe ink-jetting is very versatile when you want to make patterns or very fine features with these materials,\u201d Shen said. \u201cThe fact that the polymers are so soluble makes it quite easy to process them using anything that would spread an ink.\u201d\u003C\/p\u003E\u003Cp\u003EIn addition to the researchers already mentioned, the paper\u2019s co-authors include Justin Kerszulis and Rayford Bulloch from Georgia Tech, Michael Kuepfert from BASF in Tarrytown, New York; and Aubrey Dyer from Clayton State University in Morrow, Georgia.\u003C\/p\u003E\u003Cp\u003E\u003Cstrong\u003ECITATION\u003C\/strong\u003E: Anna M. \u00d6sterholm, et al., \u201cFour Shades of Brown: Tuning of Electrochromic Polymer Blends Toward High-Contrast Eyewear,\u201d (ACS Applied Materials \u0026amp; Interfaces, 2015). \u003Ca href=\u0022http:\/\/www.dx.doi.org\/10.1021\/am507063d\u0022\u003Ehttp:\/\/www.dx.doi.org\/10.1021\/am507063d\u003C\/a\u003E\u003C\/p\u003E\u003Cp\u003E\u003Cstrong\u003EResearch News\u003C\/strong\u003E\u003Cbr \/\u003E\u003Cstrong\u003EGeorgia Institute of Technology\u003C\/strong\u003E\u003Cbr \/\u003E\u003Cstrong\u003E177 North Avenue\u003C\/strong\u003E\u003Cbr \/\u003E\u003Cstrong\u003EAtlanta, Georgia 30332-0181 USA\u003C\/strong\u003E\u003C\/p\u003E\u003Cp\u003E\u003Cstrong\u003EMedia Relations Contacts\u003C\/strong\u003E: John Toon (404-894-6986) (\u003Ca href=\u0022mailto:jtoon@gatech.edu\u0022\u003Ejtoon@gatech.edu\u003C\/a\u003E) or Brett Israel (404-385-1933) (\u003Ca href=\u0022mailto:brett.israel@comm.gatech.edu\u0022\u003Ebrett.israel@comm.gatech.edu\u003C\/a\u003E).\u003C\/p\u003E\u003Cp\u003E\u003Cstrong\u003EWriter\u003C\/strong\u003E: John Toon\u003C\/p\u003E","summary":null,"format":"limited_html"}],"field_subtitle":"","field_summary":[{"value":"\u003Cp\u003EResearchers have created a broad color palette of electrochromic polymers, materials that can be used for sunglasses, window tinting and other applications that rely on electrical current to produce color changes. The materials could allow sunglasses that change from clear to colored in seconds, at the push of a button.\u003C\/p\u003E","format":"limited_html"}],"field_summary_sentence":[{"value":"Researchers have created a broad color palette of electrochromic polymers, materials that can be used for sunglasses, window tinting and other applications that rely on electrical current to produce color changes."}],"uid":"27303","created_gmt":"2015-02-09 13:51:27","changed_gmt":"2016-10-08 03:01:50","author":"John Toon","boilerplate_text":"","field_publication":"","field_article_url":"","dateline":{"date":"2015-02-09T00:00:00-05:00","iso_date":"2015-02-09T00:00:00-05:00","tz":"America\/New_York"},"extras":[],"hg_media":{"374521":{"id":"374521","type":"image","title":"Creating films of electrochromic polymers","body":null,"created":"1449246194","gmt_created":"2015-12-04 16:23:14","changed":"1475894265","gmt_changed":"2016-10-08 02:37:45","alt":"Creating films of electrochromic 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