16th June 2008 - 10:33 PM
Ferroelectric materials behave as piezoelectric ones do, but more efficiently, once they have been polarized. More interesting for a cloth, as I expect PVDF to be easily spun and woven - though it is uncommon. More comfortable than a ceramic, probably.
I have read for less than 6 months that some manufacturer of military batteries had made a material with controllable porosity - to separate electrodes from the electrolyte and unite them when needed? Forgotten who, where, when, and worse, how. It was discussed on this forum. Have a look at MIT's Technology Review also?
If you can choose the liquid, the answer is definitely yes. They are called ferrofluids - and an electric equivalent exists - and get some stiffness if you apply a magnetic field, because this aligns the magnetic particles they contain. Used to actively adjust the effectiveness of car dampers.
Apart from piezo- and ferroelectricity, whose effect is small, you may consider shape memory alloys http://en.wikipedia.org/wiki/Shape_memory
. Parts made from them take one from two shapes depending on the temperature. If you want to make active clothes that regulate the skin temperature, maybe. But they are metals.
Maybe you can tell more? Porous to which gas or fluid, at what temperature, how much porous, what kind of control power you have?