Purely entropic self-assembly of the bicontinuous Ia3̅d gyroid phase in equilibrium hard-pear systems
| Autor: | Matthieu Marechal, Laurence Ellison, Philipp W. A. Schönhöfer, Gerd E. Schröder-Turk, Douglas J. Cleaver |
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| Jazyk: | angličtina |
| Rok vydání: | 2017 |
| Předmět: |
Materials science
Biomedical Engineering Biophysics Bioengineering 02 engineering and technology 01 natural sciences Biochemistry Biomaterials symbols.namesake Liquid crystal 0103 physical sciences Gaussian curvature 010306 general physics QC Phase diagram Minimal surface Isotropy Articles 021001 nanoscience & nanotechnology Condensed Matter::Soft Condensed Matter Chemical physics symbols Self-assembly 0210 nano-technology Voronoi diagram Biotechnology Gyroid |
| ISSN: | 2042-8898 |
| Popis: | We investigate a model of hard pear-shaped particles which forms the bicontinuous Ia d structure by entropic self-assembly, extending the previous observations of Barmes et al. (2003 Phys. Rev. E 68 , 021708. ( doi:10.1103/PhysRevE.68.021708 )) and Ellison et al. (2006 Phys. Rev. Lett. 97 , 237801. ( doi:10.1103/PhysRevLett.97.237801 )). We specifically provide the complete phase diagram of this system, with global density and particle shape as the two variable parameters, incorporating the gyroid phase as well as disordered isotropic, smectic and nematic phases. The phase diagram is obtained by two methods, one being a compression–decompression study and the other being a continuous change of the particle shape parameter at constant density. Additionally, we probe the mechanism by which interdigitating sheets of pears in these systems create surfaces with negative Gauss curvature, which is needed to form the gyroid minimal surface. This is achieved by the use of Voronoi tessellation, whereby both the shape and volume of Voronoi cells can be assessed in regard to the local Gauss curvature of the gyroid minimal surface. Through this, we show that the mechanisms prevalent in this entropy-driven system differ from those found in systems which form gyroid structures in nature (lipid bilayers) and from synthesized materials (di-block copolymers) and where the formation of the gyroid is enthalpically driven. We further argue that the gyroid phase formed in these systems is a realization of a modulated splay-bend phase in which the conventional nematic has been predicted to be destabilized at the mesoscale due to molecular-scale coupling of polar and orientational degrees of freedom. |
| Databáze: | OpenAIRE |
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