Structure of nematic liquid crystalline elastomers under uniaxial deformation.
We have used in situ x-ray diffraction and calorimetry to study liquid crystalline elastomers prepared using a one-step photopolymerization method. We used suspended weights to stretch free-standing crystalline elastomer films. With the mechanical stress parallel to the initial director, we observed a gradual nematic to isotropic transition with increasing temperature. The thermal evolution of the nematic order parameter on cooling, together with the observation of isotropic-nematic coexistence over a broad temperature range, suggests that the heterogeneity in the samples introduces a distribution of transition temperatures. With the mechanical stress perpendicular to the initial director, we observed both uniform director rotation and stripe formation, depending on the details of sample preparation.
Zhang
Fan
F
Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA.
Heiney
Paul A
PA
Srinivasan
Amritha
A
Naciri
Jawad
J
Ratna
Banahalli
B