Researchers have created an unusual polymer that can change colour and return to its original colour 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 22 July issue and reproduced in a 25 July posting of Scientific American.
The base polymer is a polydiacetylene with peptide side chains introduced during a multi-step polymerisation 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 nanofibre that could be processed into various shapes. Fibres can be made by extrusion; membranes can be made by coating, and hydrogels may be formed by moulding.
Polymers that change colour are called thermochromic. Such polymers have been created before but they are slow to change colour 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 colour quickly even at temperatures up to 390° F.