Computational Physics Seminar
Wednesday 20th May, 2015
11:30, Rm. 620, Lidow Physics Building
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Image details on Prof. Selinger's webpage
From Topology to Morphology: Defects, Shape Evolution, and
Auto-origami in Soft Matter
Robin Selinger, Liquid Crystal Institute, Kent State University
We explore novel mechanisms of pattern formation in soft matter,
examining why a lipid membrane crumples during a phase transition
and how stimuli-responsive liquid crystal polymer films can be patterned
to induce programmed shape transformations. In both of these materials,
whose constituent molecules align to form orientationally
ordered phases, topological defects play a key role: they drive changes
in morphology by inducing curvature. In lipid membranes cooled through a
phase transition into the tilted “gel” phase, we theorize that defects
nucleate spontaneously and then coarsen via kinetic competition between
defect pair-annihilation and membrane shape evolution. We explore this
process via simulation using a coarse-grained model  and also
study membranes with nematic order . Next we examine the role of
defects in stimuli-responsive liquid crystal polymers, which flex when
exposed to light or a change of temperature. If a precise pattern of
defects is induced in the sample when it is cross-linked,
a process known as “blueprinting,” then under stimulus an initially
flat film will twist, curl, or fold into a complex shape, a form of
programmed auto-origami. We use 3-d nonlinear finite element simulation
studies to explore the mechanism by which the complete trajectory of
motion is encoded in the sample’s nematic director field,
and compare with relevant experiments .
Work supported by NSF-DMR 1106014, NSF-DMR-1409658, and NSF-CMMI 1436565.
 LS Hirst, A Ossowski, M Fraser, J Geng, JV Selinger,
and RLB Selinger, PNAS110, 3242 (2013).
 TS Nguyen, J Geng,
RLB Selinger, and JV Selinger, Soft Matter 9,8314-8326 (2013).
LT e Haan, V Gimenez-Pinto, A Konya, TS Nguyen, JMN Verjans,
Cs Sánchez-Somolinos, JV Selinger, RLB Selinger, DJ Broer, APHJ Schenning, Advanced Functional Materials 24, 1251 (2014).
Check this webpage at http://phycomp.technion.ac.il/~phr76ja/CPsem.html or the noticeboards outside Rm 603 or Rm 315
for updates and changes. View previous seminars in this series.