A thermally driven liquid crystalline elastomer bending actuator was prepared with extended cycling capabilities. This device operated with strain rates of 1 Hz displacement and 0.13 Hz recovery starting from 25.1 degree(s)C to a maximum of 150 degree(s)C. The device is a bending actuator having a multilaminated material structure. Observed displacements were lower than previous freestanding liquid crystalline elastomer films due to the constraints imposed on the liquid crystalline elastomer by the device architecture. A device operated with low power of less than 2 W and cycled over a 1000 times successfully.
Ordered liquid crystal elastomer films exhibit anisotropic deformations on macroscopic length scales on changing the orientational order of the liquid crystal group by external stimuli such as temperature and electric field. We have developed laterally attached side-chain nematic elastomers with mechanical properties approaching stress, strain and time scale of skeletal muscle activation. The mechanical and structural characterization has led to the ability to improve desired physical properties such as backbone extension and coupling between the backbone and liquid crystal side chain. We have studied the effect of the coupling length on the change in the conformational entropy of the backbone and the viscoelastic behavior. In this paper we discuss the results of our stress relaxation tests.
The growth of insoluble and intractable thin organic films is presently reported by a novel self-assembly technique. Bifunctional 8,8'-dihydroxy-5,5'-biquinoline is reactively self-assembly with diethyl zinc to form a linear coordination polymer. These films were characterized by FTIR, UV/VIS spectroscopy, profilometry, and photoluminescence measurements. The film growth on glass or indium-tin oxide coated substrates was monitored by increasing absorbance at 396.6 nm using UV/VIS spectroscopy and profilometry. FTIR spectroscopy indicated that the self- assembled films are polymeric in nature. The reduction of end-group hydroxyls and a significant red-shift of the photoluminescence emission spectrum with respect to zinc bisquinoline powder was attributed to an increase in conjugation length. Single layer light emitting diodes fabricated int his fashion exhibited an orange electroluminescence, consistent with the corresponding photoluminescence spectrum.
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