Chemistry

Like human beings, the so-called nanoporous materials are breathing… They can open or close under the effect of various factors such as pressure, temperature, light or in presence of gas or solvents. But if their “breathing” looks like the functioning of our lungs, these materials can inflate up to 230%! And they are able to capture and release gaseous or liquid chemicals, in a controlled way. That is to say the number of applications envisaged, for example for storing hydrogen and greenhouse gas or even targeting drug release.

An unexpected result

A major concern, these materials are far from having unveiled all their secrets! It is what has found a Franco-German team, including researchers from the Institut de recherche de Chimie Paris (CNRS/Chimie ParisTech) and from the Institut Charles Gerhardt de Montpellier (CNRS/Université de Montpellier/ENSCM), when developing one of these materials called DUT-49. Contrary to their belief, when pressure is increased for a sample of DUT-49 to absorb more gas, the material contracts suddenly and releases its contents. Exactly as if, when inhaling, the lungs contracted and expelled the air that they contained.

Experimentally observed, this unexpected result has been confirmed by other measurements, in particular numerical ones. A series of simulations has been performed on GENCI’s supercomputer Turing, operated at Idris, with the quantum chemistry code for solids CRYSTAL14 in its massively parallel version: “The calculations are made typically on 2,048 cores, by successive blocks of 20 hours”, François-Xavier Coudert, researcher at CNRS, explained. The global project (test phases, choice of the quantum computing methodology, technical and parallelization parameters) represented around 1 million core hours in 2015.

1 million core hours on Turing

“The main characteristic of DUT-49 is its very large size counting no less than 1,728 atoms in the crystalline mesh”, the scientist underlined. “With such a number of atoms all took into account in the quantum computing, our simulations would have been totally impossible to perform on a smaller architecture than the Turing’s one”.

The surprising physical properties of DUT-49, able to capture and store gas until a certain limit, could lead to developing nanometric switches and sensors. The material's deflation is a strong response to a small event triggered from an easily detected threshold value.

As an extension of this work, that has been published in Nature, on 6 April 2016, François-Xavier Coudert and his research team received 6 million core hours on the supercomputer Curie in the context of GENCI’s special session for studying same material family.

More information: http://www2.cnrs.fr/en/2737.htm

Matériau nanoporeux DUT-49

View of DUT-49
© S. Krause / Technische Universität Dresden