26 research outputs found
Structure of nanoscale-pitch helical phases: blue phase and twist-bend nematic phase resolved by resonant soft X-ray scattering
Periodic structures of phases with orientational order of molecules, but
homogenous electron density distribution: a short pitch cholesteric, blue phase
and twist-bend nematic phase, were probed by a resonant soft x-ray scattering
(RSoXS) at the carbon K-edge. The theoretical model shows that in case of a
simple heliconical nematic structure two resonant signals corresponding to the
full and half pitch band should be present, while only the full pitch band is
observed in experiment. This suggests that the twist-bend nematic phase has
complex structure with a double-helix, built of two interlocked, shifted
helices. We confirm that the helical pitch in the twist-bend nematic phase is
in a 10 nm range, for both, the chiral and achiral materials. We also show that
the symmetry of a blue phase can unambiguously be determined through a resonant
enhancement of x-ray diffraction signals, by including polarization effects,
which are found to be an important indicator in phase structure determination
Do the short helices exist in the nematic TB phase?
Dimeric compounds forming twist-bend nematic, Ntb, phase show unusual optical textures related to the formation of arrays of focal conic defects (FCDs). Some of the focal conics exhibit submicron internal structure with 8 nm periodicity, which is very close to that found in the crystalline phase of the material, that might suggest surface freezing
Supramolecular liquid crystals exhibiting a chiral twist-bend nematic phase
Funding The work was supported by the National Science Centre (Poland) under the grant no. 2016/22/A/ST5/00319. Acknowledgements RW gratefully thanks the Carnegie Trust for the Universities of Scotland for the award of a PhD Scholarship (2015–2018).Peer reviewedPublisher PD
Multi-level chirality in liquid crystals formed by achiral molecules
M.S., D.P., and N.V. acknowledge the support of the National Science Centre (Poland) under the grant no. 2016/22/A/ST5/00319. E.G. acknowledges the funding from the Foundation for Polish Science through the Sabbatical Fellowships Program. N.V. acknowledges the support of the Slovenian Research Agency (ARRS), through the research core funding no. P1-0055. R.W. gratefully acknowledges the Carnegie Trust for the Universities of Scotland for funding the award of a PhD scholarship. The beamline 11.0.1.2 at the Advanced Light Source at the Lawrence Berkeley National Laboratory is supported by the director of the Office of Science, Office of Basic Energy Sciences, of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231.Peer reviewedPublisher PD
Heliconical smectic phases formed by achiral molecules
M.S. acknowledges the support of the US National Science Foundation I2CAM International Materials Institute Award, Grant DMR-1411344 and NSF grant DMR-1307674. D.P., E.G. acknowledges the support of the National Science Centre (Poland) under the grant no. 2016/22/A/ST5/00319. R.W. gratefully acknowledges the Carnegie Trust for the Universities of Scotland for the award of a PhD studentship. The beamline 11.0.1.2 at the Advanced Light Source at the Lawrence Berkeley National Laboratory is supported by the Director of the Office of Science, Office of Basic Energy Sciences, of the U.S. Department of Energy under Contract No. DE-AC02- 05CH11231. Addendum: Heliconical smectic phases formed by achiral molecules Published: 17 July 2018, https://doi.org/10.1038/s41467-018-05334-x "We would like to make our readers aware of the related publications by S.P. Sreenilayam et al. (Nat. Commun. 7, 11369 (2016) and Phys. Rev. Mat. 1, 035604 (2017)), which report the spontaneous helix formation in a polar smectic liquid crystal phase made of achiral bent-core mesogens."Peer reviewedPublisher PD
Sulfur-linked cyanobiphenyl-based liquid crystal dimers and the twist-bend nematic phase
Acknowledgements EG and DP acknowledge the support of the National Science Centre (Poland): (Grant Number 2016/22/A/ST5/00319). We acknowledge the use of Beamline 5.3.1 and 11.0.1.2 of the Advanced Light Source supported by the Director of the Office of Science, Office of Basic Energy Science, of The U.S. Department of Energy under contract no. DE-AC02-05CH11231. We thank Alex Liebman-Pelaez for designing the heating stage used for TReXS measurement.Peer reviewedPostprin
Distinct differences in the nanoscale behaviors of the twist-bend liquid crystal phase of a flexible linear trimer and homologous dimer
This work was supported by National Science Foundation Materials Research Science and Engineering Center Grant DMR-1420736 and Grant DMR-1307674. M.R.T. acknowledges support from the Advanced Light Source Doctoral Fellowship in Residence offered by Lawrence Berkeley National Laboratory. M.S. acknowledges the support of the US National Science Foundation I2CAM International Materials Institute Award, Grant DMR-1411344. We acknowledge use of beamlines 11.0.1.2 and 7.3.3. of the Advanced Light Source supported by the Director of the Office of Science, Office of Basic Energy Sciences, of the US Department of Energy under Contract DE-AC02-05CH11231.Peer reviewedPublisher PD