Abstract
We study theoretically the molecular origins of the fascinating, and still debated, nematic-nematic phase transition exhibited by symmetric, statistically achiral, mesogenic dimers. A simple molecular model that mimics the key features and symmetry (C2V) of this class of mesogens is presented. In the mean-field approximation, the model yields up to three positionally disordered phases, one isotropic and two nematic. The low temperature nematic phase (NX) has a local two-fold symmetry axis, which is also a direction of molecular polar ordering and is tightly twisted about a macroscopic phase axis. The onset of polar ordering generates spontaneous chiral symmetry breaking and the formation of chiral domains of opposite handedness, manifested primarily by the twisting of the polar director. Within these domains the statistical balance between the enantiomer conformations is slightly shifted and the principal axes of the ordering tensors of the molecular segments twist at constant tilt angles with the helical axis. Key experimental results on the NX phase of liquid crystalline dimers are discussed in the light of the theoretical predictions of the model, which are also contrasted with the predictions of the twist-bend nematic model.
References
Apr 13, 1987·Physical Review Letters·J S Patel, R B Meyer
Apr 20, 2004·Physical Review Letters·L A MadsenE T Samulski
Sep 27, 2006·The Journal of Chemical Physics·Jorge PeónJacqueline Quintana-H
Jan 15, 2011·Physical Review Letters·V P PanovG H Mehl
Nov 9, 2011·Physical Review. E, Statistical, Nonlinear, and Soft Matter Physics·M CestariH Zimmermann
Jun 12, 2012·The Journal of Physical Chemistry. B·Laetitia BeguinHerbert Zimmermann
Jun 19, 2013·Physical Review. E, Statistical, Nonlinear, and Soft Matter Physics·Shaikh M ShamidJonathan V Selinger
Aug 27, 2013·Physical Review Letters·C MeyerI Dozov
Sep 6, 2013·Proceedings of the National Academy of Sciences of the United States of America·Dong ChenNoel A Clark
Nov 6, 2013·Nature Communications·V BorshchO D Lavrentovich
Nov 16, 2013·Physical Review. E, Statistical, Nonlinear, and Soft Matter Physics·V L GoloD O Sinitsyn
Feb 4, 2014·Physical Review. E, Statistical, Nonlinear, and Soft Matter Physics·Stavros D PeroukidisDemetri J Photinos
Jul 16, 2014·Physical Review. E, Statistical, Nonlinear, and Soft Matter Physics·P K ChallaA Jákli
Oct 24, 2014·Soft Matter·Cristina GrecoAlberta Ferrarini
Jan 13, 2015·Soft Matter·Anke HoffmannDemetri J Photinos
Apr 23, 2015·Chemistry : a European Journal·Richard J MandleJohn W Goodby
Aug 19, 2015·Soft Matter·Craig T ArchboldJohn W Goodby
Sep 24, 2015·The Journal of Chemical Physics·Raffaele TavaroneHolger Stark
Oct 16, 2015·Physical Review. E, Statistical, Nonlinear, and Soft Matter Physics·G BarberoI Lelidis
Nov 10, 2015·Physical Review Letters·Cristina Greco, Alberta Ferrarini
Citations
Nov 8, 2016·Scientific Reports·Richard J MandleJohn W Goodby
May 18, 2017·Physical Chemistry Chemical Physics : PCCP·W D StevensonG H Mehl
Oct 27, 2016·Chemphyschem : a European Journal of Chemical Physics and Physical Chemistry·Taizo MoriWaka Nakanishi
Mar 13, 2018·Soft Matter·Emily E PocockJohn W Goodby
Mar 17, 2016·Physical Chemistry Chemical Physics : PCCP·J W EmsleyG H Mehl
Jul 5, 2016·Physical Chemistry Chemical Physics : PCCP·N SebastiánA Eremin
Oct 17, 2018·Soft Matter·Anamarija KneŽevićAndreja Lesac
Apr 28, 2016·The European Physical Journal. E, Soft Matter·M A Osipov, G Pajak
Dec 21, 2019·Chemistry : a European Journal·Anne LehmannCarsten Tschierske
Oct 19, 2017·Scientific Reports·Richard J MandleJohn W Goodby
Sep 23, 2019·The Journal of Chemical Physics·K MerkelG H Mehl
Sep 9, 2016·Soft Matter·Wojciech TomczykLech Longa
Oct 6, 2016·Chemistry : a European Journal·Richard J Mandle, John W Goodby
Oct 13, 2018·Proceedings of the National Academy of Sciences of the United States of America·Grzegorz PająkAgnieszka Chrzanowska
Dec 25, 2019·Physical Review. E·Epifanio G Virga
Feb 20, 2020·Physical Review. E·M P RossetoR S Zola
Apr 19, 2016·Soft Matter·Shokir A PardaevS Sprunt
Oct 11, 2016·Soft Matter·Richard J Mandle
Jan 20, 2018·Physical Review. E·J W EmsleyH Zimmermann
Feb 20, 2020·Physical Review. E·Andrea Pedrini, Epifanio G Virga
Feb 11, 2021·Physical Chemistry Chemical Physics : PCCP·Katarzyna MerkelAntoni Kocot
Feb 16, 2021·Physical Chemistry Chemical Physics : PCCP·R SahaA Jákli
Oct 25, 2017·The Journal of Physical Chemistry. B·Anant KumarDemetri J Photinos