1
|
Steroid-Based Liquid Crystalline Polymers: Responsive and Biocompatible Materials of the Future. CRYSTALS 2022. [DOI: 10.3390/cryst12071000] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Steroid-based liquid crystal polymers and co-polymers have come a long way, with new and significant advances being made every year. This paper reviews some of the recent key developments in steroid-based liquid crystal polymers and co-polymers. It covers the structure–property relationship between cholesterol and sterol-based compounds and their corresponding polymers, and the influence of chemical structure and synthesis conditions on the liquid crystalline behaviour. An overview of the nature of self-assembly of these materials in solvents and through polymerisation is given. The role of liquid crystalline properties in the applications of these materials, in the creation of nano-objects, drug delivery and biomedicine and photonic and electronic devices, is discussed.
Collapse
|
2
|
Kiselev AD, Chigrinov VG, Pasechnik SV, Dubtsov AV. Photoinduced reordering in thin azo-dye films and light-induced reorientation dynamics of the nematic liquid-crystal easy axis. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2012; 86:011706. [PMID: 23005436 DOI: 10.1103/physreve.86.011706] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/17/2012] [Indexed: 06/01/2023]
Abstract
We theoretically study the kinetics of photoinduced reordering triggered by linearly polarized (LP) reorienting light in thin azo-dye films that were initially illuminated with LP ultraviolet pumping beam. The process of reordering is treated as a rotational diffusion of molecules in the light intensity-dependent mean-field potential. The two-dimensional diffusion model which is based on the free energy rotational Fokker-Planck equation and describes the regime of in-plane reorientation is generalized to analyze the dynamics of the azo-dye order parameter tensor at varying polarization azimuth of the reorienting light. It is found that, in the photosteady state, the intensity of LP reorienting light determines the scalar order parameter (the largest eigenvalue of the order parameter tensor), whereas the steady state orientation of the corresponding eigenvector (the in-plane principal axis) depends solely on the polarization azimuth. We show that, under certain conditions, reorientation takes place only if the reorienting light intensity exceeds its critical value. Such threshold behavior is predicted to occur in the bistability region provided that the initial principal axis lies in the polarization plane of reorienting light. The model is used to interpret the experimental data on the light-induced azimuthal gliding of the liquid-crystal easy axis on photoaligned azo-dye substrates.
Collapse
Affiliation(s)
- Alexei D Kiselev
- Institute of Physics of National Academy of Sciences of Ukraine, prospekt Nauki 46, 03028 Kiev, Ukraine.
| | | | | | | |
Collapse
|
3
|
Kiselev AD, Chigrinov VG, Kwok HS. Kinetics of photoinduced ordering in azo-dye films: two-state and diffusion models. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2009; 80:011706. [PMID: 19658717 DOI: 10.1103/physreve.80.011706] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/05/2009] [Indexed: 05/28/2023]
Abstract
We theoretically study the kinetics of photoinduced ordering in azo-dye photoaligning layers and present the results of modeling performed using two different phenomenological approaches. A phenomenological two-state model is deduced from the master equation for the one-particle distribution functions of an ensemble of two-level molecular systems by specifying the angular redistribution probabilities and by expressing the order parameter correlation functions in terms of the order parameter tensor. Using an alternative approach that describes light-induced reorientation of azo-dye molecules in terms of a rotational Brownian motion, we formulate the two-dimensional diffusion model as the free energy Fokker-Planck equation simplified for the limiting regime of purely in-plane reorientation. The models are employed to interpret the irradiation time dependence of the absorption order parameters defined in terms of the principal extinction (absorption) coefficients. Using the exact solution to the light transmission problem for a biaxially anisotropic absorbing layer, these coefficients are extracted from the absorbance-vs-incidence angle curves measured at different irradiation doses for the probe light linearly polarized parallel and perpendicular to the plane of incidence. It is found that, in the azo-dye films, the transient photoinduced structures are biaxially anisotropic whereas the photosteady and the initial states are uniaxial.
Collapse
Affiliation(s)
- Alexei D Kiselev
- Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong.
| | | | | |
Collapse
|
4
|
Affiliation(s)
- Michel Dumont
- a Institut d'Optique Théorique et Appliquée, Bǎt 503 , BP 147, 91403 , ORSAY cedex , France Fax:
| |
Collapse
|
5
|
Kiselev AD, Chigrinov V, Huang DD. Photoinduced ordering and anchoring properties of azo-dye films. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2005; 72:061703. [PMID: 16485960 DOI: 10.1103/physreve.72.061703] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/23/2005] [Indexed: 05/06/2023]
Abstract
We study both theoretically and experimentally the anchoring properties of photoaligning azo-dye films in contact with a nematic liquid crystal depending on the photoinduced ordering of azo-dye molecules. In the mean field approximation, we found that the bare surface anchoring energy depends linearly on the azo-dye order parameter and the azimuthal anchoring strength decays to zero in the limit of vanishing photoinduced ordering. From the absorption dichroism spectra measured in azo-dye films that are prepared from an azo-dye derivative with polymerizable terminal groups we obtain the dependence of the dichroic ratio on the irradiation dose. We also measure the polar and azimuthal anchoring strengths in nematic liquid crystal (NLC) cells aligned by the azo-dye films and derive the anchoring strengths as functions of the dichroic ratio, which is proportional to the photoinduced order parameter. Although linear fitting of the experimental data for both anchoring strengths gives reasonable results, it, predicts vanishing of the azimuthal anchoring strength at some nonzero value of the azo-dye order parameter, in contradiction with theory. By using a simple phenomenological model we show that this discrepancy can be attributed to the difference between the surface and bulk order parameters in the films. The measured polar anchoring energy is found to be an order of magnitude higher than the azimuthal strength. Our theory suggests that the quadrupole term of the spherical harmonics expansion for the azo-dye-NLC intermolecular potential might be of importance for the understanding of this difference.
Collapse
Affiliation(s)
- Alexei D Kiselev
- Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong.
| | | | | |
Collapse
|
6
|
Wang Y, Hu JS, Zhang BY, Jiang TY. New thermochromic liquid-crystalline polymer: Synthesis and phase behavior. J Appl Polym Sci 2005. [DOI: 10.1002/app.22040] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
|
7
|
Hu JS, Zhang BY, Wang Y, Meng FB. Synthesis and phase behavior of side-chain liquid-crystalline polymers containing malachite green lactone groups. ACTA ACUST UNITED AC 2004. [DOI: 10.1002/pola.20266] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
|
8
|
Yaroshchuk OV, Kiselev AD, Zakrevskyy Y, Bidna T, Kelly J, Chien LC, Lindau J. Photoinduced three-dimensional orientational order in side chain liquid crystalline azopolymers. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2003; 68:011803. [PMID: 12935167 DOI: 10.1103/physreve.68.011803] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/25/2003] [Indexed: 05/24/2023]
Abstract
We apply experimental technique based on the combination of methods dealing with principal refractive indices and absorption coefficients to study the photoinduced three-dimensional (3D) orientational order in the films of liquid crystalline (LC) azopolymers. The technique is used to identify 3D orientational configurations of trans azobenzene chromophores and to characterize the degree of ordering in terms of order parameters. We study two types of LC azopolymers which form structures with preferred in-plane and out-of-plane alignment of azochromophores, respectively. Using irradiation with the polarized light of two different wavelengths, we find that the kinetics of photoinduced anisotropy can be dominated by either photoreorientation (angular redistribution of trans chromophores) or photoselection (angular selective trans-cis isomerization) mechanisms depending on the wavelength. At the early stages of irradiation, the films of both azopolymers are biaxial. This biaxiality disappears on reaching a state of photosaturation. In the regime of photoselection, the photosaturated state of the film is optically isotropic. But, in the case of the photoreorientation mechanism, anisotropy of this state is uniaxial with the optical axis dependent on the preferential alignment of azochromophores. We formulate the phenomenological model describing the kinetics of photoinduced anisotropy in terms of the isomer concentrations and the order parameter tensor. We present the numerical results for absorption coefficients that are found to be in good agreement with the experimental data. The model is also used to interpret the effect of changing the mechanism with the wavelength of the pumping light.
Collapse
Affiliation(s)
- O V Yaroshchuk
- Institute of Physics of NASU, prospekt Nauki 46, 03028 Kyïv, Ukraine.
| | | | | | | | | | | | | |
Collapse
|
9
|
Affiliation(s)
- Almeria Natansohn
- Department of Chemistry, Queen's University, Kingston, Ontario, Canada
| | | |
Collapse
|
10
|
Delaire JA, Nakatani K. Linear and Nonlinear Optical Properties of Photochromic Molecules and Materials. Chem Rev 2000; 100:1817-1846. [PMID: 11777422 DOI: 10.1021/cr980078m] [Citation(s) in RCA: 1026] [Impact Index Per Article: 42.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Jacques A. Delaire
- Laboratoire de Photophysique et de Photochimie Supramoléculaires et Macromoléculaires (PPSM, UMR 8531 of CNRS), Ecole Normale Supérieure de Cachan, 94235 Cachan Cedex, France
| | | |
Collapse
|
11
|
|
12
|
Hattori H, Uryu T. Synthesis and properties of photochromic liquid-crystalline copolymers containing both spironaphthoxazine and cholesteryl groups. ACTA ACUST UNITED AC 2000. [DOI: 10.1002/(sici)1099-0518(20000301)38:5<887::aid-pola13>3.0.co;2-g] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
|
13
|
Yamada K, Yamada S. Structural Effects on the Interaction between cis-Dialkoxyazobenzene and a Pyridinium Compound at the Glass-Heptane Interface as Studied by in Situ Second Harmonic Generation. J Colloid Interface Sci 1999; 216:440-443. [PMID: 10421755 DOI: 10.1006/jcis.1999.6338] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The in situ optical second harmonic generation (SHG) technique was applied to the direct investigation of interactions between cis-dialkoxyazobenzene and a pyridinium compound at the glass-heptane interface. The SHG response due to noncentrosymmetric adsorption of the SHG-active cis-isomer was profoundly dependent on the structure of the pyridinium compound preadsorbed at the glass surface. It is suggested that the cis-isomer can interact preferentially with a bipyridinium compound in which the two pyridinium moieties are spatially separated to be able to interact snugly with the two phenoxy moieties of cis-dialkoxyazobenzene. Copyright 1999 Academic Press.
Collapse
Affiliation(s)
- K Yamada
- Department of Materials Physics and Chemistry, Kyushu University, Hakozaki, Fukuoka, 812-8581, Japan
| | | |
Collapse
|
14
|
Dumont M, El Osman A. On spontaneous and photoinduced orientational mobility of dye molecules in polymers. Chem Phys 1999. [DOI: 10.1016/s0301-0104(99)00096-8] [Citation(s) in RCA: 111] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
|
15
|
Blinov LM, Kozlovsky MV, Cipparrone G. Photochromism and holographic grating recording on a chiral side-chain liquid crystalline copolymer containing azobenzene chromophores. Chem Phys 1999. [DOI: 10.1016/s0301-0104(99)00104-4] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
|
16
|
Yamada K, Yonemura H, Matsuo T, Yamada S. Second harmonic generation measurements of azobenzene desorption and photochemistry at the interface between an alkane solvent and a glass plate modified with a pyridinium compound. J Photochem Photobiol A Chem 1998. [DOI: 10.1016/s1010-6030(98)00223-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
|
17
|
Schönhoff M, Mertesdorf M, Lösche M. Mechanism of Photoreorientation of Azobenzene Dyes in Molecular Films. ACTA ACUST UNITED AC 1996. [DOI: 10.1021/jp952052u] [Citation(s) in RCA: 93] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Monika Schönhoff
- Max-Planck-Institute of Colloid and Interface Science, Rudower Chaussée 5, D-12489 Berlin, Germany
| | - Michael Mertesdorf
- Max-Planck-Institute of Colloid and Interface Science, Rudower Chaussée 5, D-12489 Berlin, Germany
| | - Mathias Lösche
- Institute of Experimental Physics I, Leipzig University, Linnéstrasse 5, D-04103 Leipzig, Germany
| |
Collapse
|