| 1. |
- Lagerwall, J. P. F., et al.
(författare)
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Chiral smectic C subphases induced by mixing a bistereogenic antiferroelectric liquid crystal with a non-chiral liquid crystal
- 2005
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Ingår i: Ferroelectrics. - : Informa UK Limited. - 0015-0193 .- 1563-5112. ; 315, s. 221-230
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Tidskriftsartikel (refereegranskat)abstract
- By mixing a bistereogenic antiferroelectric liquid crystal (AFLC) compound, exhibiting only the SmQ* and SmC a * mesophases, with the achiral N-SmC liquid crystal HOAB we could induce all three AFLC SmC-type subphases, SmC α *, SmC β * and SmC γ *. This seems to be in contradiction with two recent postulations regarding the subphase stability, one of which suggests that the subphases appear as a result of strong chiral interactions, the other that these phases require high smectic order, something one would generally not expect in mixtures. We have studied the helical pitch, optical tilt angle, spontaneous polarization and the x-ray diffraction due to the smectic layering, as a function of mixing ratio in order to better understand the relation between phase sequence and mixture composition. The smectic layer spacing shows a strongly non-linear behavior, suggesting that the basic structure of the pure AFLC substance is retained up to a HOAB content of about 75%.
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| 2. |
- Liang, H. L., et al.
(författare)
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Tuning the defect configurations in nematic and smectic liquid crystalline shells
- 2013
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Ingår i: Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences. - : The Royal Society. - 1364-503X .- 1471-2962. ; 371:1988
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Tidskriftsartikel (refereegranskat)abstract
- Thin liquid crystalline shells surrounding and surrounded by aqueous phases can be conveniently produced using a nested capillary microfluidic system, as was first demonstrated by Fernandez-Nieves et al. in 2007. By choosing particular combinations of stabilizers in the internal and external phases, different types of alignment, uniform or hybrid, can be ensured within the shell. Here, we investigate shells in the nematic and smectic phases under varying boundary conditions, focusing in particular on textural transformations during phase transitions, on the interaction between topological defects in the director field and inclusions in the liquid crystal (LC), and on the possibility to relocate defects within the shell by rotating the shell in the gravitational field. We demonstrate that inclusions in a shell can seed defects that cannot form in a pristine shell, adding a further means of tuning the defect configuration, and that shells in which the internal aqueous phase is not density matched with the LC will gently rearrange the internal structure upon a rotation that changes the influence of gravity. Because the defects can act as anchor points for added linker molecules, allowing self-assembly of adjacent shells, the various arrangements of defects developing in these shells and the possibility of tuning the result by modifying boundary conditions, LC phase, thickness and diameter of the shell or applying external forces make this new LC configuration very attractive.
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| 3. |
- Trollsås, M., et al.
(författare)
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The influence of the molecular structure on the second-order nonlinear optical properties of pyroelectric liquid crystalline polymers
- 1998
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Ingår i: American Chemical Society Symposium Series (ACS). - Washington, DC : American Chemical Society. - 0097-6156 .- 1947-5918. ; 695, s. 315-327
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Tidskriftsartikel (refereegranskat)abstract
- Pyroelectric Liquid Crystal Polymers (PLCP), a novel class of material with intrinsic polar order developed in our laboratory, are discussed. Thin films (2-4µm) of PLCP were prepared by photopolymerization of ferroelectric liquid crystalline monomers in the chiral smectic C (SmC*) phase. The poly(acrylate) materials have been structurally modified in order to improve their nonlinear optical and thermal properties. Further are their longterm nonlinear optical properties discussed based on results from second harmonic generation (SHG), spontaneous polarization (Ps), and dielectric spectroscopy.
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| 4. |
- Lagerwall, J. P. F., et al.
(författare)
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Vätskekristallin mjuk materia
- 2009
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Ingår i: Fysikaktuellt. ; :3, s. 18-19
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)
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| 5. |
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