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Microphase separation driven transitions in macromolecular liquid crystals by computer simulations

Wednesday 20th March 2013 - 16:00 to 16:50
INI Seminar Room 1
We present the results of some recent simulations of macromolecular liquid crystal systems that undergo order-disorder transitions driven by a microphase separation. Molecular dynamics simulations are performed to study a liquid crystal elastomer of a side-chain architecture crosslinked in the SmA phase. Several effects have been observed: (i) the increase of the SmA-I transition temperature as the result of crosslinking; (ii) memory effects in liquid crystallinity and shape when the elastomer is driven through the Sm-I transition; (iii) both cases of homogeneous director reorientation and stripe formation when the load is applied along the nematic director [1]. In another set of results we consider bulk self-assembly of liquid crystal dendrimers studied by means of coarse-grained molecular dynamics simulations. We discuss the details of the modelling and its application to polymer-modified gold nanoparticles. The particular model dendrimer being studied demonstrates conforma tional bistability, with both rod-like and disc-like conformations stable at lower temperatures. Each conformation can be induced by the external field of appropriate symmetry, promoting further self-assembly of macromolecules into a bulk monodomain SmA or a columnar phase, respectively [2]. The domains of both phases are found to coexist and influence the system properties in a broad temperature interval including transition to the macroscopically isotropic phase. We also discuss the effect of surface anchoring on the self-assembly of these macromolecules [3].

[1] J.M.Ilnytskyi, M.Saphiannikova, D.Neher, M.P.Allen, Soft Matter (2012), DOI: 10.1039/c2sm26499d [2] J.M.Ilnytskyi, J.S.Lintuvuori, M.R.Wilson, Condens. Matter Phys. 13, 33001 (2010). [3] J.M.Ilnytskyi, M.Schoen, M.R.Wilson, in preparation.
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Presentation Material: 
University of Cambridge Research Councils UK
    Clay Mathematics Institute London Mathematical Society NM Rothschild and Sons