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Dr. Gregor Skačej: Molecular modeling of liquid crystal elastomers

Date: 3. 10. 2012
Source: Monday physics colloquium
Ponedeljek, 8. oktobra 2012, ob 16:15 v predavalnici F1, FMF UL, Jadranska 19, Ljubljana

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Povzetek:

   Molecular modeling of liquid crystal elastomers

   Dr. Gregor Skačej, Fakulteta za matematiko in fiziko, Univerza v Ljubljani

Liquid crystal elastomers (LCE) are soft functional materials consisting of weakly crosslinked polymer networks with embedded liquid crystalline (mesogenic) molecules. Consequently, LCE are characterized by a pronounced coupling between macroscopic strain and orientational mesogenic order. As the latter can be controlled by external stimuli such as temperature, electric field, or ultraviolet light, LCE have great potential for application as sensors and actuators [1].

In this talk large-scale molecular simulations of swollen main-chain LCE will be presented. The simulated experiments include temperature scans, stress-strain runs, and the application of an external electric field. So far, isostress Monte Carlo simulations of LCE have been capable of reproducing isotropic, nematic and smectic phases, as well as a stress-induced isotropic-to-nematic transition [2]. Moreover, a transversal electric field has been seen to induce nematic director rotation resulting in orientational stripe domains [3].

The rather extensive simulation output can also be used to predict typical experimental observables, such as LCE sample dimensions, specific heat, deuterium magnetic resonance spectra, and scattered X-ray patterns.

[1] M. Warner and E. M. Terentjev, Liquid Crystal Elastomers (Oxford University Press, Oxford 2003)
[2] G. Skačej and C. Zannoni, Softmatter 7, 9983 (2011)
[3] G. Skačej and C. Zannoni, Proc. Natl. Acad. Sci. USA 109, 10193 (2012)