| 1. |
- Drevensek-Olenik, I., et al.
(författare)
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Ferroelectric switching of electrically commanded alignment layers for liquid crystal displays
- 2006
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Ingår i: J.Appl.Phys.. - : AIP Publishing. - 0021-8979. ; 100
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Tidskriftsartikel (refereegranskat)abstract
- Optical second harmonic generation (SHG) was used to probe the structural and dynamic properties of electrically commanded alignment layers for liquid crystal displays. The layers were 200 nm thick and were made of siloxane-based side chain ferroelectric liquid crystal polymer (FLCP). The effect of an external dc electric field in the range of 0–2 V/µm on the SHG signal was probed in an empty sandwich cell and in a cell filled with an isotropic liquid (hexadecane). In both cases the nonlinear induced polarization shows characteristics of the "V-shaped" switching, which is associated with a relatively minor reorientational perturbation of the film. This signifies a presence of domain structure, which is strongly pinned to the substrates. The values of switching times deduced from the SHG response are two orders of magnitude larger from the values obtained by optical birefringence measurements. This observation suggests that in the top surface layer of the FLCP, which is mainly responsible for the birefringence and also for the so-called electrically commanded surface effect, the reorientation of the polymer side chains takes place much faster than in the regions close to the substrate. ©2006 American Institute of Physics
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| 2. |
- Kunstelj, K, et al.
(författare)
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Switching of Electrically Commanded Alignment Layers Probed by Optical Second Harmonic Generation
- 2006
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Ingår i: Molecular Crystals and Liquid Crystals. - : Informa UK Limited. - 1563-5287 .- 1542-1406 .- 1058-7276. ; 450:1, s. 127/[327] - 139/[339]
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Tidskriftsartikel (refereegranskat)abstract
- Optical second harmonic generation (SHG) was used to probe the response of a 200 nm thick electrically commanded alignment layer made of ferroelectric liquid crystal polymer (FLCP) film to an external DC electric field. The results show that for the field magnitudes in the range 0-2 V/ m the field induced reorientation effects represent only a relatively minor structural perturbation of the film. The switching process is monostable and shows characteristics of the "V-shaped" switching. The response time of the SHG signal is relatively longer than what is measured for the bulk FLCP. Several mechanisms are considered as possible reasons for that.
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| 3. |
- Licen, M., et al.
(författare)
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Correlation between structural properties and iridescent colors of cellulose nanocrystalline films
- 2016
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Ingår i: Cellulose. - : Springer Science and Business Media LLC. - 0969-0239 .- 1572-882X. ; 23:6, s. 3601-3609
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Tidskriftsartikel (refereegranskat)abstract
- We investigate the effect of shear flow applied during the drying of aqueous suspension of cellulose nanocrystals on optical reflective properties and structural characteristics of the resulting solidified films. Shear flow can significantly improve internal structural homogeneity of the films, while its effect on optical reflective properties is relatively minor. The measured width of the selective reflection peak is an order of magnitude larger than expected for an ideal helically modulated structure, which reflects a distribution of pitch values and possibly also of regimes of distorted helical modulation. We attribute these imperfections to the broad size distribution of the cellulose nanocrystals.
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