Kyoto University researchers have designed a temperature-controllable copper-based material for sieving or storing different kinds of gases. The rationale used to design the material, described in the journal Science, could act as a blueprint for developing nanoporous materials with a wide variety of energy, medical and environmental applications.

The porous nanomaterials that are currently used for gas separation and storage are not tuneable: their pores are persistent and rigid. Susumu Kitagawa, Nobuhiko Hosono, and their colleagues of Kyoto University's Institute for Integrated Cell-Material Sciences (iCeMS) wanted to find a way to dynamically change pore sizes in this type of material.

They designed a porous coordination polymer that was formed of copper atoms linked by butterfly-shaped ligands made from isophthalic acid and phenothiazine-5,5-dioxide. The resultant material was comprised of tiny nanocages, each with eight protruding channels. At very low temperatures, the channels connecting the nanocages were so narrow that they were effectively closed. As the temperature was increased, the channels opened more and more, allowing gas molecules to move between the cages.

The team found that a gas could move or become locked within the material depending on the size of the gas's molecules and how wide the material's channels were at a given temperature. They also found that the material adsorbed a gas at high temperatures and held it in when ambient temperatures were applied, effectively storing the gas.

Furthermore, when the researchers applied gas mixtures to the material, they found they could separate the gases based on the temperature applied. For example, the material selectively adsorbed oxygen when a gas mixture of equal concentrations of oxygen and argon was applied for one hour at a temperature of -93 C and a pressure of one bar. The material selectively adsorbed oxygen even when the argon concentration in the mixture was significantly higher than that of the oxygen.

"The presented porous system that uses a robust framework with thermally active molecular functionality realizes temperature-regulated gas adsorption/desorption by design, in which local flexibility at the aperture plays a pivotal role," the researchers conclude.

Research paper

Related Links
Kyoto University
Space Technology News - Applications and Research

Tweet

Thanks for being here; We need your help. The Space Media Network continues to grow but revenues have never been harder to maintain. With the rise of Ad Blockers, and Facebook - our traditional revenue sources via quality network advertising continues to decline. And unlike so many other news sites, we don't have a paywall - with those annoying usernames and passwords. Our news coverage takes time and effort to publish 365 days a year. If you find our news sites informative and useful then please consider becoming a regular supporter or for now make a one off contribution.
SpaceMediaNetwork Contributor $5 Billed Once credit card or paypal		SpaceMediaNetwork Monthly Supporter $5 Billed Monthly paypal only

A new method developed to produce precursors for high-strength carbon fibers processing
Nizhny Novgorod, Russia (SPX) Jan 23, 2019
Carbon fiber is an important structural material of the 21st century. Due to its high strength, which is not inferior to metal alloys, in combination with low specific weight and high oxidative stability, it is an indispensable material for airspace and shipbuilding industry, construction, medicine, sports industry, and in other high-tech industry sectors. The main method of carbon fiber production involves heat treatment of synthetic fibers obtained from polymers based on acrylonitrile. The quali ... read more