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Smart Liquid Goes Dark in the Heat

posted by chromas on Thursday April 04 2019, @04:00PM   
from the heat-me dept.

upstart writes:

Submitted via IRC for Bytram

Smart liquid goes dark in the heat

A smart liquid that darkens dramatically in response to rising temperature has been developed by researchers at A*STAR. The nanowire-based thermochromic liquid's tunable color-changing behavior was retained even after hundreds of heat-cool cycles.

[...] Previous thermochromic liquids have usually been based on organic dyes or liquid crystals. Although amenable to industrial-scale production, organic dyes tend to degrade upon exposure to light, while liquid crystals require encapsulation to avoid degradation in air. A thermochromic liquid that overcomes these limitations has been discovered by Wen-Ya Wu and her colleagues from the A*STAR Institute of Materials Research and Engineering, in collaboration with researchers at the National University of Singapore.

Wu's research is focused on semiconductor nanocrystals, which form a colloidal suspension in certain solvents, and which are known for their broad light absorption and high photostability. "While exploring the synthesis of colloidal antimony selenide (Sb2Se3) nanoparticles, we serendipitously discovered that they formed crystalline nanowires upon heating and dissolved into their molecular precursors upon cooling, in a certain mixture of solvents," Wu says.

Thanks to their broad light-absorbing behavior, a vial of Sb2Se3 nanowires formed by heating can appear very dark. But a solution of their molecular precursors, which the nanowires revert to upon cooling, are relatively transparent. "This phenomenon formed the basis for developing these materials as liquid-based thermochromics," Wu says.

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Original Submission

• Re:use case Re:use case (Score: 4, Insightful) by RamiK on Thursday April 04 2019, @04:34PM (1 child)

  by RamiK (1813) on Thursday April 04 2019, @04:34PM (#824577)

  The obvious mention was smart windows - It gets hot, darken the outside windows so they don't let the sunlight in.

  The team showed that the thermochromic liquid's color-changing behavior is long-lived and robust. A solution of the molecular precursors was stable even after two years in ambient conditions, and could be heated and cooled hundreds of times without any loss of performance. An additional advantage was that the color change transition temperature could be tuned to be anywhere between 35 and 140 degrees Celsius by simply adding a small amount of tin chloride to the mixture.

  Isn't 35°C a bit too high? I would even guess the reason they ended up doing two years worth of experimentation on it was over trying and failing to lower it by 10-20°C...

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• Re:use case (Score: 1) by RandomFactor on Thursday April 04 2019, @04:41PM

  by RandomFactor (3682) on Thursday April 04 2019, @04:41PM (#824583) Journal

  Sure seems like it would be.

  Unless there is an efficient mechanism to retain heat such that the glass is consistently warmer than the environment.

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