Modeling Sm-A LCEs with defects
Seminar Room 1, Newton Institute
AbstractSm-A LCEs are known to exhibit very different responses to stretching parallel and perpendicular to the smectic layer normal.
Side-chain Sm-A LCE films in particular have been extensively studied both theoretically and experimentally since the work of Nishikawa and Finkelmann in 1999. Typically a drastic drop in the elastic modulus after a critical stress can be observed when stretching parallel to the layer normal. Adams and Warner (2005) derived a model for Sm-A LCEs that explains this softening behaviour by the onset of microstructure also theoretically. The simplest of these microstructures consists in a fine scale buckling of layers. However, more complex microstructures are possible, as was shown in (Adams, Conti, DeSimone, & Dolzmann, 2008).
Our aim is to adapt this theory to try to understand the recent experimental results of Komp and Finkelmann (2007), whose Sm-A LCE films show different optical behaviour and behaviour of the order parameter on stretching parallel to the director when compared with the response of the original Nishikawa and Finkelmann LCE. We believe that the difference may be related to the presence of defects in the sample, as suggested by Komp and Finkelmann: the difficulty lies in how to model this situation.