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New structural model of a chiral cubic liquid crystalline phase
Nataša Vaupotič1, Mirosław Salamończyk, Joanna Matraszek
1Department of Physics, Faculty of Natural Sciences and Mathematics, University of Maribor, Koroška 160, 2000 Maribor, Slovenia. natasa.vaupotic@um.si.
Physical Chemistry Chemical Physics : PCCP
|May 30, 2020
Summary
Novel thermotropic mesogenic materials display unique chiral cubic and achiral double gyroid phases. The chiral phase features interconnected hexagonal networks on a minimal surface, explaining low energy transitions.
Area of Science:
- Materials Science
- Crystallography
- Soft Matter Physics
Background:
- Thermotropic mesogenic materials exhibit liquid crystal phases with ordered molecular arrangements.
- Cubic phases in mesogens are known for complex three-dimensional structures.
- Understanding phase transitions and structural properties is crucial for material design.
Purpose of the Study:
- To investigate the structural properties of novel thermotropic mesogenic materials.
- To elucidate the molecular arrangement within the chiral cubic phase.
- To correlate structural features with observed phase transition thermodynamics.
Main Methods:
- X-ray diffraction experiments to determine structural parameters.
- Computational modeling to support experimental findings and visualize structures.
- Analysis of molecular packing and symmetry within different mesophases.
Main Results:
- Identification of both achiral double gyroid (Ia3[combining macron]d) and chiral cubic (Im3[combining macron]m) phases.
- The chiral cubic phase consists of interconnected hexagonal micelles and channels.
- Structural analysis revealed these hexagons are embedded on a degenerate Neovius minimal surface.
- Elastic energy calculations showed similarity between chiral cubic and double gyroid phases.
- Chirality arises from non-planar hexagons and alternating molecular inclinations, amplified by steric effects.
Conclusions:
- The study provides a detailed structural model for the chiral cubic phase in thermotropic mesogens.
- The observed low enthalpy change during phase transition is explained by the similar elastic energies of the two phases.
- Molecular chirality is intrinsically linked to the non-planar hexagonal network and steric interactions.
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