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UV timer inspired by the human skin: A polymer composite based on photochromes

Wednesday (07.06.2017)
17:30 - 17:50 Förde II
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Most smart materials that were produced and investigated in the past decade were inspired by the nature. A very efficient UV sensor existing in the nature is the human skin. To protect the human skin from sun burns several solutions were put forth such as UV protection cream, UV repellent upholstery. Set back with these solutions is that the sun screening layer wear off leaving the skin exposed to the radiation. Inspired by the human skin a polymer composite based on a photochromic derivative of spirooxazine is presented work. Photochrome used here is a molecule that undergo a well known spiro-mero reversible isomerization under UV light indicated by a color change. The isomerization is either reversed by the visible light illumination or by thermal relaxation. The polymer matrix utilized is the solvent free polythiourethane (PTU). The polymer composite is produced by dispersing a photochromic derivative of spirooxazines (purchased from Smart Physik) into the PTU. The concentration of the photochrome is kept at 0.5 wt% of PTU. When the photochromic polymer composite is exposed to the direct sunlight it turns purple. The PTU/photochrome composite was completely covered with a sunscreen spray (SPF 50+) and is placed under the sunlight. As the sunscreen fade the colorless polymer composite turns purple indicating the area exposed to UV irradiation. Additionally, an outlook on the employment of such photochromic species in industrially relevant materials such as glass fiber reinforced polymer composites will be presented.


Sindu Shree
Kiel University