Jaroslav Ilnytskyi, Institute for Condensed Matter Physics
Abstract: Polymeric liquid crystals combine the features of both the polymer and liquid crystal. Their fine-tuning is possible on the stage of synthesis which leads to a number of practical applications (high strength plastics, displays, optical data storage).
We present some recent results in molecular dynamics simulations of such systems. Liquid crystalline dendrimer is studied in isotropic, nematic and smectic A solvent and we concentrate on orientational relaxation of the macromolecule and its equilibrium shape depending on the phase of the solvent and the way the terminal mesogens are attached to the dendritic core. The results are relevant in a view of the relation between the molecular shape and bulk phase.
The second problem addresses the origin of photo-induced deformations in azobenzene-containing polymer films. We reproduced the opposite sign of the deformations under uniform linearly polarized light in liquid crystalline and amorphous films, respectively. The simulations shed some more light on underlying microscopic mechanisms of these deformations.
The third problem is the memory effects in liquid crystalline elastomers that are potentially attractive for the application as artificial muscles. In our molecular dynamics simulations we reproduce the reversibility of the shape of lightly crosslinked melt of polymer liquid crystal when driven via the smectic-isotropic transition.
The examples presented demonstrate the potential of molecular dynamics simulations in clarification of the microscopic mechanism behind various effects and are a starting point for simulation driven predictions of the properties of new materials.
Presented at PSSM Workshop on Liquid Crystals and Colloidal Dispersions
http://www.icmp.lviv.ua/statphys2009/pssm/
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