Distinct differences in the nanoscale behaviors of the twist–bend liquid crystal phase of a flexible linear trimer and homologous dimer

We synthesized the liquid crystal dimer and trimer members of a series of flexible linear oligomers and characterized their microscopic and nanoscopic properties using resonant soft X-ray scattering and a number of other experimental techniques. On the microscopic scale, the twist–bend phases of the...

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Published inProceedings of the National Academy of Sciences - PNAS Vol. 116; no. 22; pp. 10698 - 10704
Main Authors Tuchband, Michael R., Paterson, Daniel A., Salamończyk, Mirosław, Norman, Victoria A., Scarbrough, Alyssa N., Forsyth, Ewan, Garcia, Edgardo, Wang, Cheng, Storey, John M. D., Walba, David M., Sprunt, Samuel, Jákli, Antal, Zhu, Chenhui, Imrie, Corrie T., Clark, Noel A.
Format Journal Article
LanguageEnglish
Published United States National Academy of Sciences 28.05.2019
National Academy of Sciences, Washington, DC (United States)
SeriesPNAS Plus
Subjects
CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS
Dimers
heliconical
Homology
liquid crystal
Liquid crystals
Oligomers
Physical Sciences
PNAS Plus
RSoXS
Soft x rays
Temperature dependence
trimer
Trimers
twist–bend nematic
X-ray scattering
RSoXS
heliconical
trimer
liquid crystal
twist–bend nematic
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Summary:We synthesized the liquid crystal dimer and trimer members of a series of flexible linear oligomers and characterized their microscopic and nanoscopic properties using resonant soft X-ray scattering and a number of other experimental techniques. On the microscopic scale, the twist–bend phases of the dimer and trimer appear essentially identical. However, while the liquid crystal dimer exhibits a temperature-dependent variation of its twist–bend helical pitch varying from 100 to 170 Å on heating, the trimer exhibits an essentially temperature-independent pitch of 66 Å, significantly shorter than those reported for other twist–bend forming materials in the literature. We attribute this to a specific combination of intrinsic conformational bend of the trimer molecules and a sterically favorable intercalation of the trimers over a commensurate fraction (two-thirds) of the molecular length. We develop a geometric model of the twist–bend phase for these materials with the molecules arranging into helical chain structures, and we fully determine their respective geometric parameters.
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USDOE Office of Science (SC), Basic Energy Sciences (BES)
National Science Foundation (NSF)
ALS Doctoral Fellowship in Residence; AC02-05CH11231; DMR-1420736; DMR-1307674
Author contributions: M.R.T., A.J., C.Z., C.T.I., and N.A.C. designed research; M.R.T., D.A.P., M.S., V.A.N., E.F., and N.A.C. performed research; D.A.P., A.N.S., E.G., J.M.D.S., D.M.W., and C.T.I. contributed new reagents/analytic tools; M.R.T., D.A.P., M.S., E.G., C.W., S.S., A.J., C.Z., C.T.I., and N.A.C. analyzed data; C.W. provided experiment support; and M.R.T., S.S., A.J., C.T.I., and N.A.C. wrote the paper.
Edited by Frank S. Bates, University of Minnesota, Minneapolis, MN, and approved April 11, 2019 (received for review January 27, 2019)
ISSN:0027-8424
1091-6490
DOI:10.1073/pnas.1821372116