Shocking new way to create nanoporous materials revealed

Nov 27, 2011

Scientists have developed a new method of creating nanoporous materials with potential applications in everything from water purification to chemical sensors.

In order to produce a porous material it is necessary to have multiple components. When the minor component is removed, small are left in its place. Until now, creating nanoporous was limiting as it was believed the minor component had to be connected throughout the structure as well as to the outside in order for it to be removed.

However, new research published today (Sunday, 27 November) in the journal has demonstrated a much more effective, flexible method called collective osmotic shock (COS) for creating porous structures. The research, by scientists at the University of Cambridge, has shown how by using osmotic forces even structures with minor components entirely encapsulated in a matrix can be made porous (or nanoporous).

The lead author, Dr Easan Sivaniah from the University of Cambridge's Cavendish Laboratory, explains how the process works: "The experiment is rather similar to the classroom demonstration using a balloon containing . How does one release the salt from the balloon? The answer is to put the balloon in a bath of . The salt can't leave the balloon but the water can enter, and it does so to reduce the saltiness in the balloon. As more water enters, the balloon swells, and eventually bursts, releasing the salt completely.

"In our experiments, we essentially show this works in materials with these trapped minor components, leading to a series of bursts that connect together and to the outside, releasing the trapped components and leaving an open ."

The researchers have also demonstrated how the nanoporous materials created by the unique process can be used to develop filters capable of removing very small dyes from water.

Dr Sivaniah added: "It is currently an efficient filter system that could be used in countries with poor access to fresh potable water, or to remove heavy metals and industrial waste products from ground water sources. Though, with development, we hope it can also be used in making sea-water drinkable using low-tech and low-power routes."

Other applications were explored in collaboration with groups having expertise in photonics (Dr Hernan Miguez, University of Sevilla) and optoelectronics (Professor Sir Richard Friend, Cavendish Laboratory). Light-emitting devices were demonstrated using titania electrodes templated from COS materials whilst the novel stack-like arrangement of materials provide uniquely efficient photonic multilayers with potential applications as sensors that change colour in response to absorbing trace amounts of chemicals, or for use in optical components.

Dr Sivaniah added, "We are currently exploring a number of applications, to include use in light-emitting devices, solar cells, electrodes for supercapacitors as well as fuels cells."

Explore further: Nanoparticles give up forensic secrets

More information: The paper 'Collective osmotic shock in ordered materials' will be published in the 27 November 2011 edition of Nature Materials. DOI: 10.1038/nmat3179

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Sean_W
3 / 5 (2) Nov 27, 2011
A clever idea; it sounds very practical and could yield many new applications plus make current applications for nano-porous materials less expensive.
despinos
not rated yet Nov 28, 2011
Well, the process is not explained at all in the article. Just "osmotic forces" and a fancy name (collective osmotic shock) are mentioned, but nothing else.
eachus
not rated yet Nov 29, 2011
Well, the process is not explained at all in the article. Just "osmotic forces" and a fancy name (collective osmotic shock) are mentioned, but nothing else.

From the Free Dictionary:
os·mo·sis (z-mss, s-) n. pl. os·mo·ses (-sz)
1. a. Diffusion of fluid through a semipermeable membrane from a solution with a low solute concentration to a solution with a higher solute concentration until there is an equal concentration of fluid on both sides of the membrane.

(I skipped the definitions that did not apply.)

Now do you understand the description, which is perfectly clear? If you need more detail, grab a kitchen sponge (the artificial kind) and look how it is made. The major component is the sponge you are holding in your hand. The minor component was dissolved away to leave the holes (pores). This new process uses osmotic pressure to break open any completely encapsulated pores. That allows using less of the minor component, leading to smaller and narrower pores.
eachus
not rated yet Nov 29, 2011
Well, the process is not explained at all in the article. Just "osmotic forces" and a fancy name (collective osmotic shock) are mentioned, but nothing else.


From the Free Dictionary:
os mo sis (z-mss, s-) n. pl. os mo ses (-sz)
1. a. Diffusion of fluid through a semipermeable membrane from a solution with a low solute concentration to a solution with a higher solute concentration until there is an equal concentration of fluid on both sides of the membrane.
(I skipped the definitions that did not apply.)
Now do you understand the description, which is perfectly clear? If you need more detail, grab a kitchen sponge (the artificial kind) and look how it is made. The major component is the sponge you are holding in your hand. The minor component was dissolved away to leave the holes (pores). This new process uses osmotic pressure to break open any completely encapsulated pores. That allows using less of the minor component, leading to smaller and narrower pores.