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Probing and controlling liquid crystal helical nanofilaments.
Chenhui Zhu1, Cheng Wang1, Anthony Young1
1†Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States.
Nano Letters
|April 14, 2015
Summary
Researchers measured the helical pitch in bent-core liquid crystals for the first time. The helical half-pitch of NOBOW was 120 nm, tunable by adding guest molecules.
Area of Science:
- Materials Science
- Condensed Matter Physics
- Crystallography
Background:
- Bent-core liquid crystals exhibit unique B4 phases with helical nanofilaments.
- Understanding the helical pitch is crucial for their potential applications.
Purpose of the Study:
- To perform the first in situ measurement of the helical pitch in the B4 phase of bent-core liquid crystals.
- To investigate the temperature dependence and tunability of this helical structure.
Main Methods:
- Utilized linearly polarized, resonant soft X-ray scattering at the carbon K-edge.
- Analyzed anisotropic scattering peaks to determine the helical structure's half-pitch.
Main Results:
- Observed a strong, anisotropic scattering peak indicating the twisted smectic layer structure.
- Determined the equilibrium helical half-pitch of NOBOW to be 120 nm, largely independent of temperature.
- Demonstrated that the helical pitch can be tuned by incorporating guest organic molecules and thermal annealing.
Conclusions:
- Established a direct method for measuring helical pitch in bent-core liquid crystals.
- The helical pitch is a stable property but can be modified through molecular mixing and processing.
- Findings provide insights into the structure-property relationships of B4 phase liquid crystals.
