Piezoelectricity in ferroelectric liquid crystalline elastomers

Abstract

The direct and inverse piezoelectricity in single crystal ferroelectric liquid crystalline elastomers was measured by means of purpose-made experimental setups. As expected the observed effects depended strongly on temperature and the strength of the applied alternating electric field; additionally they could be strongly enhanced by a superimposed direct current electric field. The latter resulted from a molecular amplification of the polarization vector of the single smectic layers by inducing a rotational bias of the lateral distribution of the polar groups of the mesogens. This resulted in a pronounced magnification of the (macroscopic) piezoelectric effect. Backed also by X-ray measurements, a model is suggested, which interprets the observed piezoelectricity as caused by a field-induced change of the inclination of the tilted smectic layers. The strength of the observed electromechanical effects compares well with or exceeds that of classical materials, such as barium titanate or lead±zirconate±titanate or the polymer polyvinylidene fluoride.

Living free‐radical polymerization (reversible addition–fragmentation chain transfer) of 6‐[4‐(4′‐methoxyphenyl)phenoxy]hexyl methacrylate: A route to architectural control of side‐chain liquid‐crystalline polymers

“…Since the first introduction of SCLC polymers by Finkelmann and coworkers in 1978,3, 4 there have been many studies of the effects of the molecular structures of the polymer backbones, spacer groups, and mesogenic side chains on the thermal and physical properties of these polymers 5–10. Furthermore, many studies have been reported on the applications of such polymers in areas such as ferroelectric display devices,1, 11–13 nonlinear optics,14–17 optical storage data,18 pyroelectric detectors,19 and artificial muscles 1, 20, 21…”

Liquid crystal elastomers, networks and gels: advanced smart materials

“…This problem can be overcome by using ferroelectric LC gels. 66,69,[71][72][73][74] Fig. 17 illustrates the creation of a monodomain in a ferroelectric LC elastomer.…”

Molecular‐Level Devices and Machines

“…This enables to analyse in detail the reorientation of the single molecular moieties in the supramolecular system (angle of reorientation, time constant, phase relationship) in response to an external electric field. To measure the (inverse) piezoelectric effect interferometric and x-ray methods are used [4,5]. It is discovered that FLCE in a proper crosslinking density show the highest electrostrictive coefficients which were found up to now for any material.…”

“…It is discovered that FLCE in a proper crosslinking density show the highest electrostrictive coefficients which were found up to now for any material. A microscopic interpretation of the observed marcoscopic effects will be presented [5,6].…”

“…This allows, for instance, the detection of the immunomodulating and antitumor drug substance rViscumin, active in concentrations not detectable by conventional ELISA assays. Moreover, the oligomeric DNA-streptavidin networks can be converted to well-defined supramolecular nanocircles [3], applicable as modular building blocks for the generation of novel immunological reagents [4], the construction of nanometerscaled "soft material" standards for scanning probe microscopy [5], and other fields of nanobiotechnology. Another example concerns covalent conjugates of single-stranded DNA oligomers and streptavidin [6], which can be utilized as biomolecular adapters for the immobilization of biotinylated macromolecules on surfaces via nucleic acid hybridization.…”