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SUMMARY:Hard and soft elasticity of polydomain liquid crystal elastomers -
  Biggins\, J (University of Cambridge)
DTSTART:20130627T080000Z
DTEND:20130627T084500Z
UID:TALK45942@talks.cam.ac.uk
CONTACT:Mustapha Amrani
DESCRIPTION:Liquid crystal elastomers are solids that resist deformation w
 ith an elastic modulus appropriate for rubber. However\, some special larg
 e deformations that induce the liquid-crystal order to rotate though the e
 lastomer can be imposed at almost zero stress. These deformations are said
  to be soft. Soft elasticity is now well understood in monodomain liquid c
 rystal elastomers (in which the liquid crystal order points in the same di
 rection throughout the sample) but such samples are rather difficult to pr
 epare\, especially in anything but a thin film. If a liquid crystal polyme
 r is simply crosslinked to make an elastomer\, the results will be a polyd
 omain. We model each domain of a polydomain as a small monodomain and ask 
 whether such polydomains exhibit global soft elasticity. We show that the 
 fabrication history of the sample is critical. Elstomers crosslinked in an
  isotropic state then cooled to a nematic state whilst a solid have global
  soft modes while those cooled to a nematic state then crosslinked do not.
  The addition of smectic phases allows more complicated fabrication histor
 ies with a variety of soft and hard behaviour. Finally\, I will consider w
 hether any of these polydomains can be used to build actuators. \n
LOCATION:Centre for Mathematical Sciences\, Meeting Room 2
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