Imaging liquid crystals dispersed in a ferroelectric polymer matrix by means of thermal-pulse tomography
- A new arrangement of the optical elements in a Thermal-Pulse-Tomography (TPT) setup allows to scan micrometer structures in composite and heterogeneous samples such as polymer-dispersed liquid crystals (PDLCs). The non-destructive TPT technique allows the determination of three-dimensional profiles of polarization and space charge in dielectrics. The samples under study were 12 mu m thick films of a copolymer of vinylidene fluoride with trifluoroethylene P(VDF- TrFE) (65/35) with embedded liquid-crystal droplets. The poling process was performed in direct contact well above the coercive field of the copolymer. The 3D map obtained from scanning with a 10 mu m wide spot shows elliptically shaped areas with liquid-crystal droplets. Considering the droplets as oblate spheroids, their major axis lies in the x-y plane, while their minor axis in the z direction measures 0.5 mu m or more. This result is in good agreement with scanning electron micrographs. It is believed that the major axis is overestimated due to imaging of liquid-crystalA new arrangement of the optical elements in a Thermal-Pulse-Tomography (TPT) setup allows to scan micrometer structures in composite and heterogeneous samples such as polymer-dispersed liquid crystals (PDLCs). The non-destructive TPT technique allows the determination of three-dimensional profiles of polarization and space charge in dielectrics. The samples under study were 12 mu m thick films of a copolymer of vinylidene fluoride with trifluoroethylene P(VDF- TrFE) (65/35) with embedded liquid-crystal droplets. The poling process was performed in direct contact well above the coercive field of the copolymer. The 3D map obtained from scanning with a 10 mu m wide spot shows elliptically shaped areas with liquid-crystal droplets. Considering the droplets as oblate spheroids, their major axis lies in the x-y plane, while their minor axis in the z direction measures 0.5 mu m or more. This result is in good agreement with scanning electron micrographs. It is believed that the major axis is overestimated due to imaging of liquid-crystal clusters.…
Author details: | Rosaura Flores SuárezGND, Lakshmi Meena Ganesan, Werner WirgesORCiD, Reimund GerhardORCiDGND, Axel MellingerORCiDGND |
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URL: | http://ieeexplore.ieee.org/servlet/opac?punumber=94 |
DOI: | https://doi.org/10.1109/TDEI.2010.5539683 |
ISSN: | 1070-9878 |
Publication type: | Article |
Language: | English |
Year of first publication: | 2010 |
Publication year: | 2010 |
Release date: | 2017/03/25 |
Source: | IEEE transactions on dielectrics and electrical insulation. - ISSN 1070-9878. - 17 (2010), 4, S. 1123 - 1127 |
Organizational units: | Mathematisch-Naturwissenschaftliche Fakultät / Institut für Physik und Astronomie |
Peer review: | Referiert |