UV manipulation of order and macroscopic shape in nematic elastomers.

UV isomerisation in nematic elastomers as a route to photo-mechanical transducer.

The macroscopic shape of liquid-crystalline elastomers strongly depends on the order parameter of the mesogenic groups. This order can be manipulated if photo-isomerisable groups, e.g. containing N=N bonds, are introduced into the material. We have explored the large photo-mechanical response of such an azobenzene-containing nematic elastomer at different temperatures, using force and optical b...

Modeling liquid crystal elastomers: actuators, pumps, and robots

We model the dynamics of shape evolution of liquid crystal elastomers (LCE) in three dimensions using finite element elastodynamics. The model predicts the macroscopic mechanical response induced by changes in nematic order, e.g. by heating or cooling through the isotropic/nematic transition or, in azo-doped materials, by exposure to light. We model the performance of LCE actuator devices inclu...

Order and Disorder in Liquid-Crystalline Elastomers

Order and frustration play an important role in liquid-crystalline polymer networks (elastomers). The first part of this review is concerned with elastomers in the nematic state and starts with a discussion of nematic polymers, the properties of which are strongly determined by the anisotropy of the polymer backbone. Neutron scattering and X-ray measurements provide the basis for a description ...

Ribbon Formation in Twist-Nematic Elastomers

Nematic Elastomers (NEs) possess very interesting properties stemming from the interaction between liquid crystal order and rubber elasticity. For such materials, thermally-induced phase transition from the isotropic to the nematic phase may induce very large distortions, which in turn can affect the overall configuration of a macroscopic specimen. The behavior of NEs can be well modeled within...

Macroscopic Response of Nematic Elastomers via Relaxation of a Class of So(3)-invariant Energies