Nov 22 2018
Ghent University scientists explored how so-called metal-organic frameworks breathe as it becomes colder or hotter. With the aid of advanced computer simulations, they learned that the temperature at which these materials unexpectedly expand or shrink is modifiable. Their results allow the design of thermostats that function at the molecular level.
The study was carried out at the Center for Molecular Modeling at Ghent University supervised by Prof. V. Van Speybroeck and in partnership with the University of Vienna. It has been published in Nature Communications recently.
Ingenious pores
Metal-organic frameworks are perforated with tiny pores, measuring not more than a billionth of a meter in diameter. In spite of this limited size, the pores provide opportunities for a broad array of innovative applications. Metal-organic frameworks have thus far gained attention for the detection of chemical weapons, the capture of greenhouse gases or the transport of drugs in blood.
Materials design through computer simulations
The scientists of the Center for Molecular Modeling concentrated on the breathing versions of metal-organic frameworks. The pores of these materials open or close when they heat up or cool down. This breathing behavior brings about an unexpected increase or decrease of the volume. The Ghent researchers currently showed that the temperature at which this phenomenon takes place relies on the composition of the metal-organic frameworks. Their molecular building blocks can, therefore, be picked as a function of the temperature at which a reaction is necessary. Specifically, the switching temperature results from an understated balance between the attraction between the pore walls and the mobility of the atoms.
Molecular thermostat
The study’s findings open new viewpoints for the design of thermostats limited to a few atoms. Such materials are essential to be able to deal with the ongoing miniaturization of numerous applications, ranging from electronics to biology. The conversion of heat into volume change furthermore offers possibilities for the manipulation of energy at the smallest length scales.