Making a photo active fabric

[Daza]

Hi science guru's I'm doing some reaserch on photoactive fabrics that can change there composition when exposed to UV light. I'm in no way smart enough to know what I'm looking for so I was wondering if anyone could direct me. To give an Idea of what I'm looking for allow me to be more specific. I'm looking at fabric which can change from something that can let light throigh to something that can block light out with the transition being the disappearance of UV light turning the fabric solid.If anyone has done reaserch like this or knows where I can start my own reaserch into this there advice and help would be much appreciated.

[Sensei]

I assume you want it to be transparent/opaque in visible spectrum (so it will still be visible in IR/MW spectrum).

Even if you would find compound which reacts to UV light in the way you're interested, there still would be problem with refractive index not equal to 1.0. When light is entering medium which has different refractive index than air, beam of light is bended. e.g. we can see glass because of deformation of image behind it..

Check this video:

Why it has to react to UV light? Is it necessary? There are compounds which change light polarization when they're exposed to external electric and magnetic fields. Two such layers rotated 90 degrees (or one layer + polarization filter layer) and there is electronically controlled opaque/transparent window.

You can make crystal which is opaque and then turn transparent when you turn on/off electromagnet.

Did you hear about liquid crystals?

https://en.wikipedia.org/wiki/Liquid_crystal

 

Edited June 29, 2018 by Sensei

[Daza]

Hi Sensei,

Thanks for the vid and information. As to your questions above

On 6/29/2018 at 2:12 PM, Sensei said:

Why it has to react to UV light?

Im looking for the fabric to react to sunlight. When sun is up see through when sun down not see through.

On 6/29/2018 at 2:12 PM, Sensei said:

Did you hear about liquid crystals?

Someone mentioned that to me but for the size of the fabric im trying to create this would be way too expensive and not really practical.

The fabric doesn't need to let all light through so a colour change to something opaque would be practical.

[Endy0816]

There's photochromic pigments that might work.

Ex. Blue

Kind of cool, I have some project ideas for them myself

Best shot without something mechanical going on; changing thread spacing or releasing a gas between two layers.

Edited July 4, 2018 by Endy0816

[Daza]

Hi Endy0816,

What would you use to change the thread spacing obviously it would need to have elasticity to go back to a small thread spacing at a given time.

A gas between 2 layers seems interesting but the containment of the gas would mean the fabric would need to retain its shape and be very ridged. Im looking for the fabric to be able too move freely and be flowing.

[Endy0816]

Small motor could work. Look something like an old fashioned loom updated to allow spacing to change at a push of a button. Increase the dimensions and light will pass through easily.

I'd really look into the photochromic dyes though. Change color in the sun like you are asking. Are a bit pricey but probably the simplest option.

Edited July 4, 2018 by Endy0816

[Daza]

On 7/5/2018 at 1:25 AM, Endy0816 said:

I'd really look into the photochromic dyes though. Change color in the sun like you are asking. Are a bit pricey but probably the simplest option.

If the dye was applied to one side of the fabric would the change of the colour not alow it to be see through even if there is an alternate light source on the opposite side of the fabric?

 

[Endy0816]

Probably more translucent than transparent, but should work.