# Are there solid materials with controllable porosity?

+ 6 like - 0 dislike
119 views

In analogy to piezoelectric materials, where the application of an electrical field creates mechanical deformation in the material, I have the following question.

Are there solid materials whose porosity can be altered or controlled?

Of course, I have googled this. This lead me to a lot of websites where controllable porosity means that the porosity of a material is very-well defined when it is produced. This is not what I am looking for. I am looking for a material that can alter its porosity according to an external control quantity, such as electric voltage.

This post imported from StackExchange Physics at 2014-03-24 04:42 (UCT), posted by SE-user lomppi
asked Aug 6, 2013
Perhaps you can try googling "tunable" instead of "conytolled/-able"

This post imported from StackExchange Physics at 2014-03-24 04:43 (UCT), posted by SE-user Slaviks
I know porosity can be changed due to temperature or pressure, but as for controlling it with electricity or something that is as easily used, I am unsure. I feel that it's certainly possible though.

This post imported from StackExchange Physics at 2014-03-24 04:43 (UCT), posted by SE-user danielu13
I can imagine systems to solve the problem (porous plug under controlled pressure; dialing the temperature of a filter with nice linear expansion) and so on, but I don't know of anything as simple as the piezo response. Are there other constraints to make those kinds of idea infeasible?

This post imported from StackExchange Physics at 2014-03-24 04:43 (UCT), posted by SE-user dmckee

+ 4 like - 0 dislike

I would expect stimuli-responsive polymers to have what you're looking for, and the keyword "stimuli-responsive" may be a useful search term. The stimuli-responsive polymers undergo conformational changes in response to changes in their environment. The primary environmental control variables people use are temperature, pH, and ionic strength. But people have also looked at glucose, visible light, and electric and magnetic fields. Usually this happens in solution, but you can also make hydrogels out of these polymers. In that case, the hydrogels swell or deswell when you hit them with the stimulus.

I just found this paper, so I haven't read it, but it appears to describe exactly what you are looking for, by using stimuli-responsive polymers. The full citation is J. Mater. Chem., 2012,22, 19482-19487. I've heard of Sergiy Minko in the context of stimuli-responsive polymers, so he's probably a good person to look for.

This post imported from StackExchange Physics at 2014-03-24 04:43 (UCT), posted by SE-user Colin McFaul
answered Aug 6, 2013 by (60 points)
+ 4 like - 0 dislike

The credit should actually go to Slaviks for the wise suggestion of keywords to look for. Tunable porosity gives the following article:

• DOI:10.1002/ange.201201686 Prashant Tyagi et al. Dynamic Interactive Membranes with Pressure-Driven Tunable Porosity and Self-Healing Ability. Angewandte Chemie, 2012.

ABA triblock copolymer (pictured above) poly(styrene-co-acrylonitrile)-b-poly(ethylene oxide)-b-poly(styrene-co-acrylonitrile) (PSAN-b-PEO-b-PSAN) has been used to generate flower-like micelles.

Porosity tuning is done by changing water pressure which re-arranges the micelles.

This post imported from StackExchange Physics at 2014-03-24 04:43 (UCT), posted by SE-user Deer Hunter
answered Aug 6, 2013 by (40 points)
I agree, [Slavik]'s suggestion makes all the difference.

This post imported from StackExchange Physics at 2014-03-24 04:43 (UCT), posted by SE-user lomppi

 Please use answers only to (at least partly) answer questions. To comment, discuss, or ask for clarification, leave a comment instead. To mask links under text, please type your text, highlight it, and click the "link" button. You can then enter your link URL. Please consult the FAQ for as to how to format your post. This is the answer box; if you want to write a comment instead, please use the 'add comment' button. Live preview (may slow down editor)   Preview Your name to display (optional): Email me at this address if my answer is selected or commented on: Privacy: Your email address will only be used for sending these notifications. Anti-spam verification: If you are a human please identify the position of the character covered by the symbol $\varnothing$ in the following word:p$\hbar$ysicsOverf$\varnothing$owThen drag the red bullet below over the corresponding character of our banner. When you drop it there, the bullet changes to green (on slow internet connections after a few seconds). To avoid this verification in future, please log in or register.