title: Structure of nematic liquid crystalline elastomers under uniaxial deformation.
abstract: 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.
authors.affiliation: Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA.
authors.forename: Fan
authors.initials: F
authors.lastname: Zhang
authors.forename: Paul A
authors.initials: PA
authors.lastname: Heiney
authors.forename: Amritha
authors.initials: A
authors.lastname: Srinivasan
authors.forename: Jawad
authors.initials: J
authors.lastname: Naciri
authors.forename: Banahalli
authors.initials: B
authors.lastname: Ratna