Mesophase behaviour of polyhedral particles

Translational and orientational excluded-volume fields encoded in particles with anisotropic shapes can lead to purely entropy-driven assembly of morphologies with specific order and symmetry. To elucidate this complex correlation, we carried out detailed Monte Carlo simulations of six convex space-...

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Bibliographic Details
Published in:Nature materials 2011-03, Vol.10 (3), p.230-235
Main Authors: Escobedo, Fernando A, Agarwal, Umang
Format: Article
Language:English
Subjects:
639/301/1034/1037
639/301/119/1002
639/301/923/919
Anisotropy
Biomaterials
Chemistry and Materials Science
Computer simulation
Condensed Matter Physics
Correlation
Crystallization
Crystals
Entropy
Liquids
Materials Science
Mesophase
Monte Carlo methods
Monte Carlo simulation
Nanotechnology
Optical and Electronic Materials
Phase transitions
Phases
Plastics
Rotational
Symmetry
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Summary:Translational and orientational excluded-volume fields encoded in particles with anisotropic shapes can lead to purely entropy-driven assembly of morphologies with specific order and symmetry. To elucidate this complex correlation, we carried out detailed Monte Carlo simulations of six convex space-filling polyhedrons, namely, truncated octahedrons, rhombic dodecahedrons, hexagonal prisms, cubes, gyrobifastigiums and triangular prisms. Simulations predict the formation of various new liquid-crystalline and plastic-crystalline phases at intermediate volume fractions. By correlating these findings with particle anisotropy and rotational symmetry, simple guidelines for predicting phase behaviour of polyhedral particles are proposed: high rotational symmetry is in general conducive to mesophase formation, with low anisotropy favouring plastic-solid behaviour and intermediate anisotropy (or high uniaxial anisotropy) favouring liquid-crystalline behaviour. It is also found that dynamical disorder is crucial in defining mesophase behaviour, and that the apparent kinetic barrier for the liquid–mesophase transition is much lower for liquid crystals (orientational order) than for plastic solids (translational order). Monte Carlo simulations are performed to study the assembly of polyhedrons into various mesophases and crystalline states. The formation of new liquid-crystalline and plastic-crystalline phases is predicted at intermediate volume fractions and, by correlating these results with particle anisotropy and rotational symmetry, guidelines for predicting phase behaviour are proposed.
ISSN:1476-1122
1476-4660
DOI:10.1038/nmat2959