| Budget Amount *help |
¥2,200,000 (Direct Cost: ¥2,200,000)
Fiscal Year 2005: ¥600,000 (Direct Cost: ¥600,000)
Fiscal Year 2004: ¥1,600,000 (Direct Cost: ¥1,600,000)
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| Research Abstract |
Liquid crystal elastomers (LCEs) are unusual and complex materials that couple the elastic property with the anisotropy of the director orientation. In general, they consist of cross-linked networks of polymers with side-chain mesogens. Owing to this structure any external stimulus such as temperature, radiation or electric/magnetic fields on the polymer network gives rise to change in orientation order, and this resulting change induces shape and/or dimension deformation of LCEs. In particular, nematic LCE films exhibit strong uniaxial deformations due to their anisotropic properties. Due to the anisotropy of LCEs, the network elongates in the direction of the optical (or director) axis of the nematic below the nematic-isotropic transition temperature T_<NI>, while it behaves similarly to a conventional rubber above T_<NI>. Such a thermo-mechanical effect has much potential for useful applications such as microactuators, artificial muscles and switching devices. In the early studies o
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f LCEs, researchers focused on physical properties through the phase transition between the nematic and isotropic states.
In this research, we experimentally investigate electro-mechanical effects in LCEs previously swollen with low-molecular -weight liquid crystals (LMWLCs). Both polydomain (POLY) and monodomain (MONO) LCEs were studied. After swelling POLY and MONO LCEs with 5CB, shape changes were measured by recording the displacement of the edge of the swollen LCE at different voltages, V, and temperature. In particular, we note that, compared to unswollen LCEs, a dramatic 〜200 times decrease of the threshold field was found for electro-mechanical effects in swollen LCEs. The inverse of the response time when the field was switched on in both POLY and MONO was proportional to E^2, which is the same field dependence as the response time of LMWLCs. When the field was switched off, the relaxation time showed a field dependence different from that of LMWLCs that we attribute to relaxation of the LCE network. Less
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