By Michael Lauzon
CORRESPONDENT
Published: July 30, 2014 9:51 am ET
Updated: July 30, 2014 9:54 am ET
Researchers have created an unusual polymer that can change color and return to its original color in less than a second by changing its temperature.
Such polymers could promise applications in biological sensors and smart windows that adjust sunlight or heat exchange, according to an article in Chemical World’s July 22 issue and reproduced in a July 25 posting of Scientific American.
The base polymer is a polydiacetylene with peptide side chains introduced during a multi-step polymerization of diacetylene in UV light. Peptides are chain-like molecules made of amino acids, the same building blocks in the proteins of living things.
Lead researcher Zhengzhong Shao of Fudan University in Shanghai said in an email that the new polymer is a nanofiber that could be processed into various shapes. Fibers can be made by extrusion; membranes can be made by coating, and hydrogels may be formed by molding.
Polymers that change color are called thermochromic. Such polymers have been created before but they are slow to change color and only work in a narrow temperature range. Zhengzhong and colleagues in China, Netherlands and United Kingdom were searching for better thermochromic polymers when they discovered the new type that changed color quickly even at temperatures up to 390° F. | 
