Monodomain Liquid Crystal Main Chain Elastomers by Photocrosslinking
A new synthetic strategy for the preparation of macroscopically oriented smectic main chain liquid crystal elastomers (MC-LCE) by the photocrosslinking of laterally functionalized polyesters is presented. X-ray measurements proved the formation of the monodomain and allowed a quantitative determination of the order parameter. The thermo-actuation of our material at the phase transition from the liquid-crystalline to the isotropic phase was demonstrated by temperature dependent measurements of the sample length, showing a fully reversible shape change of � 40%. Mechanical measurements showed that the sample can be stretched by up to 60% along the smectic layer normal without any reorientatio…
Induced roughness in thin films of smectic-C* elastomers
The surface topography of a thin homeotropically oriented film of ferroelectric smectic-C* elastomer is studied by atomic force microscopy. We find that when the film is mechanically stretched, its surface becomes increasingly rough, in proportion to the applied strain. The effect depends strongly on the nature of crosslinks forming the elastomer network. The r.m.s. roughness correlations show a consistent trend [h(x) − h(0)]21/2 ~ (x/ξ)0.5. We introduce a theoretical model assuming that random disorder in the smectic tilt angle is induced by deformations via the coupling of mesogens to the elastic network. The model describes the observed power law and gives a prediction for the correlatio…