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Is there a way to make a liquid, such as a liquid crystal material, transition from cloudy or clear and vice-versa using only electric current?

By cloudy, I mean, similar to the effect that cholesterol or 5CB exhibits, thermally.

If so, where could this be obtained, and how quickly does it switch between states?

If not, how else might such an effect be achieved using electric current? I've read about the Kerr effect, but it didn't change opacity so much as refractive index, and it also appeared to use a great deal of electricity. I'm thinking something within the single volts.

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  • $\begingroup$ The would be sort of the reverse of what happens in a liquid crystal display pixel, so, it's possible. $\endgroup$ – Ben Norris Aug 18 '12 at 11:34
  • $\begingroup$ I expect that answer is "no, or at least, no any common". However, if one is interested in shutting light, he may use safe idea as in liquid crystal which can be both transparent by default and nontransparent by default. $\endgroup$ – permeakra Aug 23 '12 at 10:11
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I would expect this to exist. One major class of stimuli-responsive polymers is thermosensitive polymers. These have a sudden drop in solubility with an increase in temperature above a certain point. Depending on the particular polymer and the concentration, this transition can be accompanied by a clouding of the solution.

A review of stimuli-responsive polymers from Brent Sumerlin's group contains a section about electric field sensitive polymers. These are usually in the context of the field causing a mechanical response from the polymer. Sumerlin's review cites this paper from a Hungarian group discussing polymer gels that change shape under electric field. You would want the electric field to affect the solubility of the polymer. Sumerlin's review doesn't appear to directly mention anything exactly like that, but I would expect it to be possible.

I'm not as familiar with ionic liquids, but this paper uses an electric field to turn a hydrophobic ionic liquid hydrophilic. That's what happens with the thermosensitive polymers, and more what I was thinking of.

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  • $\begingroup$ Why was this answer voted down? I think it has merit, but I need more time to study what's been outlined here. :) $\endgroup$ – Hunter Aug 28 '12 at 1:17
  • $\begingroup$ Hmm... I'm willing to examine thermosensitive polymers for this application, provided the following: $\endgroup$ – Hunter Aug 28 '12 at 1:25
  • $\begingroup$ Hmm... I'm willing to examine thermosensitive polymers for this application, but it definitely complicates matters. I'd need a cooling jacket, and individual heating elements per cell. Further, it'd have to be a low enough temperature to not melt plastic, but not so low that I'd need refrigeration. It'd be nice if this material could be sourced easily and at low cost, also. ;) $\endgroup$ – Hunter Aug 28 '12 at 1:32
  • $\begingroup$ @CryptoQuick, the polymers I'm used to working with will undergo their transitions at temperatures below plastic melting (usually between room temperature and body temperature). Sourced easily and low cost are harder; most of these materials are still in the synthesize-it-yourself phase. $\endgroup$ – Colin McFaul Aug 28 '12 at 1:57
  • $\begingroup$ Colin, I don't suppose you'd have any updates? Perhaps something is on the shelf these days? $\endgroup$ – Hunter Jun 20 '13 at 18:17
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Electrochromic materials are produced for this purpose and are typically sold as “smart glass”.

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  • $\begingroup$ This is may be a good road to go down, and I believe Colin McFaul is providing more detail in another answer. I'm just curious if this property can be observed from all sides, or only from certain directions? $\endgroup$ – Hunter Aug 28 '12 at 1:22

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