2007 Fiscal Year Final Research Report Summary
STUDY OF THERMOMECHANICS OF SMC LIQUID-CRYSTALLINE ERASTOMERES
| Project/Area Number |
17550169
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Functional materials/Devices
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| Research Institution | Tokyo Polytechnic University |
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Principal Investigator |
HIRAOKA Kazuyuki Tokyo Polytechnic University, Faculty of engineering, Professor (50267530)
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| Co-Investigator(Kenkyū-buntansha) |
NOSE Takuhei TOKYO POLYTECHNIC UNIVERSITY, Faculty of engineering, Lecturer (20016405)
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| Project Period (FY) |
2005 – 2007
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| Keywords | liquid crystals / artificial muscles / crystal technology / polymer Physics / chemical physics / liquid-crystalline elastomers / liquid-crystalline polymers / actuators |
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| Research Abstract |
Liquid-crystalline elastomers have received increasing attention as a novel class of liquid-crystalline materials, because they develop new macroscopic features by combining the mechanical properties of polymer networks with the anisotropic structure of liquid-crystalline phases. In this year, the deformation behavior of uniaxially deformed smectic C^* elastomers has been investigated for two different types of crosslinker, namely, a hydroquinone-type crosslinker (V_<hq>) and a rod-like crosslinker (V_<rod>) to study the influence of the chemical constitution of the crosslinker on the molecular orientation and the shape memory effect. For the uniaxially deformed elastomer synthesized with the hydroquinone-type crosslinker (V_<hq>-crosslinked elastomer), the mesogens tilted at an angle of ±θM with respect to the layer normal oriented parallel to the uniaxial mechanical field, as mesogens were allowed to incline in a layer because of the flexible chemical structure of the crosslinker. According to molecular tilting, the elastomer elongated (shrank) with increasing (decreasing) temperature in the SmC^* phase. As for the uniaxially deformed elastomer synthesized with the rod-like crosslinker(V_<rod>-crosslinked elastomer), not molecular tilting but layer tilting occurred in the SmC^* phase, because the rod-like crosslinker V_<rod> was sufficiently rigid to disturb mesogens in tilting. The sample length of the V_<rod>-crosslinked elastomer was almost constant in the SmC^* phase, whereas the molecular rearrangement caused by layer tilting took place. By comparing both experimental results of the V_<hq>- and V_<rod>-crosslinked elastomers, we conclude that the reversible shape change of the elastomer is caused by the reversible change in molecular alignment, which was predominantly controlled by the crosslinking topology associated with the chemical constitution of the crosslinker.
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