Microphase separation driven transitions in macromolecular liquid crystals by computer simulations
Seminar Room 1, Newton Institute
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 . 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 . 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 .
 J.M.Ilnytskyi, M.Saphiannikova, D.Neher, M.P.Allen, Soft Matter (2012), DOI: 10.1039/c2sm26499d  J.M.Ilnytskyi, J.S.Lintuvuori, M.R.Wilson, Condens. Matter Phys. 13, 33001 (2010).  J.M.Ilnytskyi, M.Schoen, M.R.Wilson, in preparation.