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Understanding and Manipulating Helical Nanofilaments in Binary Systems with Achiral Dopants
Yu Cao1,2,3, Tianyi Tan1, David M Walba4
1Shaanxi International Research Center for Soft Matter, State Key Laboratory for Mechanical Behaviour of Materials, Xi'an Jiaotong University, Xi'an 710049, P.R. China.
Nano Letters
|May 18, 2022
Summary
We studied helical nanofilaments (HNFs) formed by NOBOW molecules. Adding 5CB dopant shortened the helical pitch, offering control for optical devices.
Area of Science:
- Materials Science
- Soft Matter Physics
- Liquid Crystals
Background:
- Bent-core molecules form helical nanofilament (HNF) liquid crystal phases.
- Understanding the relationship between dopant concentration and HNF structure is crucial for applications.
Purpose of the Study:
- To investigate the relationship between helical pitch of NOBOW HNFs and the concentration of achiral dopants (5CB and octane).
- To explore the influence of dopants on the HNF superstructure and molecular ordering.
Main Methods:
- Linearly polarized resonant soft X-ray scattering (RSoXS) was used for quantitative pitch determination.
- Theory-based simulations were employed to complement experimental observations and probe molecular helices.
Main Results:
- Helical pitch variation was directly correlated with 5CB concentration, independent of temperature.
- Doping with rodlike, immiscible 5CB shortened the helical pitch by up to 30% due to altered interfacial tension.
- A superstructure of helical 5CB, directed by the grooves of HNFs, was observed.
Conclusions:
- The study demonstrates a method to control helical pitch in HNF systems by adjusting dopant concentration.
- Findings provide insights into the phase behavior of binary liquid crystal systems.
- The ability to tune pitch length has potential applications in optical rotation devices, circularly polarized light emitters, and chirality transfer agents.
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