Discovery of a new fluidic phase
23 marca 2018
An article on a discovery of a new fluidic phase with a helical structure – SmCTB – has been published recently. The discovery has been made by scientists from University of Warsaw Faculty of Chemistry, University of Aberdeen and a multidisciplinary science laboratory in California – Lawrence Berkeley National Laboratory.
What do liquid crystals and Japan nunchaku have in common? Their structure. Nanchaku is a traditional Japan martial arts weapon consisting of two wooden sticks connected at one end by a chain. Mesogenic materials, which are similar to nunchaku in their structure, are built of two rigid mesogenic moieties linked by a flexible spacer, normally an alkyl chain. Such materials can exhibit a number of fluidic phases that belong to the group of nematics (that are used, for example, to build LCD displays) and smectics (that are characterized by high viscosity and rigidity of the structure due to layer structure).
Scientists from UW Faculty of Chemistry Laboratory of Physicochemistry of Dielectrics and Magnetics – prof. Ewa Górecka, dr hab. Damian Pociecha i dr Mirosław Salamończyk – in cooperation with scientists from University of Aberdeen and Lawrence Berkeley National Laboratory have identified, among smectic phases, a phase with properties that have been unknown so far.
Optical and structural X-ray studies have shown that this phase has a helical structure – over 3-4 layers molecules form a helix (spiral). It’s been the first time when such a structure was discovered in achiral meterials. This means that the scientists have obtained chiral structure out of achiral objects. The helical turn, which is the structural part repeating itself, is just 10-20 nanometers long. The name of the newly discovered fluidic phase is smectic CTB (SmCTB, TB meaning twist-bend).
The studied homologous series has also formed another lamellar phase, so called hexatic I (HexI), which has been known for many years. However, the study has shown that the structure of this phase is not as simple as it has been known so far. Achiral molecules form a double chiral structure on nano– and submikrometer level.
Here you can find out more about the discovery: Nature Communications
Source: www.uw.edu.pl