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Dolganov PV, Spiridenko NA, Dolganov VK. Statics and dynamics of point boojums, line and modified Saturn ring topological defects in nematic confined geometry. Eur Phys J E Soft Matter 2023; 46:121. [PMID: 38057532 DOI: 10.1140/epje/s10189-023-00387-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/09/2023] [Accepted: 11/22/2023] [Indexed: 12/08/2023]
Abstract
In this paper we study the static structure and the dynamics of topological defects associated with isotropic droplets in nematic environment. Investigations were made in confined geometry of optical cells when the droplet size was of the order of or larger than the gap of the cell. We observed the coexistence of point boojums and Saturn ring or modified Saturn ring defects. We found transformation of the Saturn ring defect to two localized broad defects at increasing the droplet size. At droplet coalescence antipodes of point and localized broad defects were born and the dynamics of their annihilation with existing defects was investigated. We found strong difference in the process of annihilation of point and localized broad defects. Microscope images of isotropic droplets in nematic environment in a planar cell. The director orientation far from the droplets is in horizontal direction. The photographs were taken with crossed vertical and horizontal polarizers (a) and with a single horizontal polarizer (b). The cell thickness is 100 μm. Droplet diameter is less than the cell thickness. 1 and 2 are point boojums, L is the Saturn ring defect.
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Affiliation(s)
- P V Dolganov
- Osipyan Institute of Solid State Physics RAS, Chernogolovka, Moscow Region, Russia, 142432.
| | - N A Spiridenko
- Osipyan Institute of Solid State Physics RAS, Chernogolovka, Moscow Region, Russia, 142432
| | - V K Dolganov
- Osipyan Institute of Solid State Physics RAS, Chernogolovka, Moscow Region, Russia, 142432
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Dolganov PV, Baklanova KD, Dolganov VK. Peculiarities of focal conic structure formed near the cholesteric-isotropic phase transition. Phys Rev E 2022; 106:014703. [PMID: 35974502 DOI: 10.1103/physreve.106.014703] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2022] [Accepted: 06/17/2022] [Indexed: 06/15/2023]
Abstract
Focal conic structure formed near the transition from the cholesteric liquid crystal phase into isotropic liquid is studied in planar cells with a combination of optical methods. Employing a procedure with slow variation of temperature, we manage to obtain regions of periodic focal conic structure with two-dimensional square ordering in the plane of the cell. Using ordered samples and materials with selective reflection in the visible spectral range, we obtain spectral and microscopic optical data which deepen our knowledge of the focal conic structure.
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Affiliation(s)
- P V Dolganov
- Institute of Solid State Physics, Russian Academy of Sciences, 142432, Chernogolovka, Moscow Region, Russia
| | - K D Baklanova
- Institute of Solid State Physics, Russian Academy of Sciences, 142432, Chernogolovka, Moscow Region, Russia
- National Research University Higher School of Economics, 101000, Moscow, Russia
| | - V K Dolganov
- Institute of Solid State Physics, Russian Academy of Sciences, 142432, Chernogolovka, Moscow Region, Russia
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Dolganov PV, Zverev AS, Baklanova KD, Dolganov VK. Quasi-two-dimensional coalescence of nematic and isotropic droplets and Rayleigh-Plateau instability in flat optical cells. Soft Matter 2021; 18:126-136. [PMID: 34817480 DOI: 10.1039/d1sm01334c] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
We investigated the coalescence of nematic droplets in an isotropic environment and that of isotropic droplets in a nematic environment in quasi-two-dimensional geometry of a flat optical cell. Two different regimes of coalescence were found. In the circular meniscus between the nematic and isotropic regions both nematic and isotropic phases exist. As a result, two bridges form at coalescence: a nematic and an isotropic bridge. In this work, we focus on the situation when nematic wets the cell surface. The coalescence of nematic droplets starts near the cell surfaces where the droplet bridge from the nematic phase is formed. An outer bridge connecting the isotropic environment is localized in the middle of the cell. When the outer bridge gets thinner it becomes unstable and breaks up. A series of pinch-offs leads to the formation of satellite droplets. On the contrary, when isotropic droplets coalesce, the coalescence starts in the middle of the cell and breaking of the bridges occurs without instability and without the formation of satellite droplets. Breakup of the outer bridge is a new example of Rayleigh-Plateau instability in addition to actively studied transformation and breaking of filaments and stretched droplets.
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Affiliation(s)
- P V Dolganov
- Institute of Solid State Physics RAS, 142432, Chernogolovka, Moscow Region, Russia.
- National Research University Higher School of Economics, Moscow, 101000, Russia
| | - A S Zverev
- Institute of Solid State Physics RAS, 142432, Chernogolovka, Moscow Region, Russia.
| | - K D Baklanova
- Institute of Solid State Physics RAS, 142432, Chernogolovka, Moscow Region, Russia.
- National Research University Higher School of Economics, Moscow, 101000, Russia
| | - V K Dolganov
- Institute of Solid State Physics RAS, 142432, Chernogolovka, Moscow Region, Russia.
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Dolganov PV, Shuravin NS, Dolganov VK, Kats EI, Stannarius R, Harth K, Trittel T, Park CS, Maclennan JE. Transient hexagonal structures in sheared emulsions of isotropic inclusions on smectic bubbles in microgravity conditions. Sci Rep 2021; 11:19144. [PMID: 34580344 PMCID: PMC8476617 DOI: 10.1038/s41598-021-98166-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2021] [Accepted: 08/19/2021] [Indexed: 11/08/2022] Open
Abstract
We describe the collective behavior of isotropic droplets dispersed over a spherical smectic bubble, observed under microgravity conditions on the International Space Station (ISS). We find that droplets can form two-dimensional hexagonal structures changing with time. Our analysis indicates the possibility of spatial and temporal periodicity of such structures of droplets. Quantitative analysis of the hexagonal structure including the first three coordination circles was performed. A peculiar periodic-in-time ordering of the droplets, related to one-dimensional motion of droplets with non-uniform velocity, was found.
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Affiliation(s)
- P V Dolganov
- Institute of Solid State Physics, Russian Academy of Sciences (ISSP RAS), 142432, Chernogolovka, Moscow Region, Russia
| | - N S Shuravin
- Institute of Solid State Physics, Russian Academy of Sciences (ISSP RAS), 142432, Chernogolovka, Moscow Region, Russia
| | - V K Dolganov
- Institute of Solid State Physics, Russian Academy of Sciences (ISSP RAS), 142432, Chernogolovka, Moscow Region, Russia.
| | - E I Kats
- L.D. Landau Institute for Theoretical Physics, Russian Academy of Sciences, 142432, Chernogolovka, Moscow Region, Russia
| | - R Stannarius
- Institute of Physics, Otto von Guericke University, 39106, Magdeburg, Germany
| | - K Harth
- Institute of Physics, Otto von Guericke University, 39106, Magdeburg, Germany
| | - T Trittel
- Institute of Physics, Otto von Guericke University, 39106, Magdeburg, Germany
| | - C S Park
- Department of Physics, University of Colorado Boulder, Boulder, CO, 80309, USA
| | - J E Maclennan
- Department of Physics, University of Colorado Boulder, Boulder, CO, 80309, USA
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Dolganov PV, Zverev AS, Baklanova KD, Dolganov VK. Dynamics of capillary coalescence and breakup: Quasi-two-dimensional nematic and isotropic droplets. Phys Rev E 2021; 104:014702. [PMID: 34412240 DOI: 10.1103/physreve.104.014702] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2021] [Accepted: 06/04/2021] [Indexed: 11/07/2022]
Abstract
We observed the formation of small satellite droplets from the bridge at droplet coalescence. Investigations were made using a Hele-Shaw cell in the two-phase region at the nematic-isotropic phase transition. In previous works on coalescence it was considered that before the start of coalescence there exists a bridge between the outer fluid connecting regions on the two sides of the droplets (outer bridge). After the start of coalescence, a bridge connecting the two droplets appears (droplet bridge) and the outer bridge is broken. We have shown that there are coalescence processes where after the start of coalescence both the droplet bridge and the outer bridge can exist. This cardinally changes the coalescence process. During the first coalescence stage the size of the outer bridge decreases and the size of the droplet bridge increases. During the second stage the outer bridge becomes unstable which leads to pinch-off, formation of pointed end domains, secondary instability, splitting of pointed end domains, and formation of satellite droplets. We found the linear dependence of the minimum bridge radius on time near bridge breakup. This behavior confirms the capillary viscous regime of bridge breakup. Our work connects two areas of fluid dynamics: coalescence and breakup with formation of satellite droplets.
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Affiliation(s)
- P V Dolganov
- Institute of Solid State Physics, Russian Academy of Sciences, 142432 Chernogolovka, Moscow district, Russia
| | - A S Zverev
- Institute of Solid State Physics, Russian Academy of Sciences, 142432 Chernogolovka, Moscow district, Russia
| | - K D Baklanova
- Institute of Solid State Physics, Russian Academy of Sciences, 142432 Chernogolovka, Moscow district, Russia.,National Research University Higher School of Economics, Moscow 101000, Russia
| | - V K Dolganov
- Institute of Solid State Physics, Russian Academy of Sciences, 142432 Chernogolovka, Moscow district, Russia
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Dolganov PV, Shuravin NS, Dolganov VK, Kats EI. Dynamics of island-meniscus coalescence in free-standing smectic films. Soft Matter 2020; 16:8506-8511. [PMID: 32840550 DOI: 10.1039/d0sm00791a] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
In free-standing smectic films islands (regions of larger thickness than the film) can be considered as two-dimensional analogues of liquid droplets in a three-dimensional medium. The dynamics of droplet coalescence is an important but up to now incompletely solved problem in non-equilibrium mechanics. Here, we report on our investigations of island coalescence with the film meniscus. This phenomenon is analogous to the coalescence of a 3D droplet with a flat liquid surface. We found that the time evolution of island dimension is described by universal power-law dependencies for different stages of coalescence. Limited agreement with existing theory was found. In particular, in the final stage of coalescence the domain dynamics differs from theoretical predictions.
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Affiliation(s)
- P V Dolganov
- Institute of Solid State Physics, Russian Academy of Sciences, Chernogolovka, Moscow Region 142432, Russia.
| | - N S Shuravin
- Institute of Solid State Physics, Russian Academy of Sciences, Chernogolovka, Moscow Region 142432, Russia.
| | - V K Dolganov
- Institute of Solid State Physics, Russian Academy of Sciences, Chernogolovka, Moscow Region 142432, Russia.
| | - E I Kats
- Landau Institute for Theoretical Physics, Russian Academy of Sciences, Moscow Region, 142432, Chernogolovka, Russia
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Dolganov PV, Shuravin NS, Dolganov VK. Coalescence of holes in two-dimensional free-standing smectic films. Phys Rev E 2020; 101:052701. [PMID: 32575317 DOI: 10.1103/physreve.101.052701] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2020] [Accepted: 03/31/2020] [Indexed: 06/11/2023]
Abstract
We investigate in free-standing smectic films coalescence of holes (circular regions with thickness smaller than the surrounding film). This process can be considered as a two-dimensional analog of coalescence of bubbles in a three-dimensional fluid. A high speed video camera was used to study the evolution of domains at different stages of coalescence. Special attention was given to investigations of the dependence of the size of the bridge between two holes at the initial stage of coalescence, which was considered in numerous theoretical works and bears information on the coalescence mechanism. It is established that the scaling law is applicable for the description of the transformation of bridges for holes of different radius R. We found that in the regime corresponding to the experimental situation the length of the bridge H increases with the scaling law H/R=(t/τ_{R})^{1/2}. The characteristic time τ_{R} determined from the scaling law is larger than the theoretical time, which can be connected with dissipation of energy both in the film and inside the holes.
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Affiliation(s)
- P V Dolganov
- Institute of Solid State Physics, Russian Academy of Sciences, Chernogolovka, Moscow Region 142432, Russia
| | - N S Shuravin
- Institute of Solid State Physics, Russian Academy of Sciences, Chernogolovka, Moscow Region 142432, Russia
| | - V K Dolganov
- Institute of Solid State Physics, Russian Academy of Sciences, Chernogolovka, Moscow Region 142432, Russia
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Abstract
Freestanding smectic films give a unique possibility to study two-dimensional coalescence. We report experimental investigations in freestanding films and detailed analysis of coalescence of islands, circular regions of larger thickness than the surrounding film. The driving force of island coalescence is the dislocation tension on the boundary between the island and the film. The obtained experimental results enable one to perform complex analysis of two-dimensional coalescence in Stokes regime and compare it to theoretical predictions. The applicability of scaling arguments for the description of the peculiarities of domain dynamics is demonstrated. The whole process of coalescence is well described by the analytical solution adapted to our case of islands in freestanding smectic films.
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Affiliation(s)
- N S Shuravin
- Institute of Solid State Physics, Russian Academy of Sciences, Chernogolovka, Moscow Region 142432, Russia
| | - P V Dolganov
- Institute of Solid State Physics, Russian Academy of Sciences, Chernogolovka, Moscow Region 142432, Russia
| | - V K Dolganov
- Institute of Solid State Physics, Russian Academy of Sciences, Chernogolovka, Moscow Region 142432, Russia
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Shuravin NS, Dolganov PV, Dolganov VK. Erratum: Coalescence of viscous two-dimensional smectic islands [Phys. Rev. E 99, 062702 (2019)]. Phys Rev E 2019; 100:019901. [PMID: 31499913 DOI: 10.1103/physreve.100.019901] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2019] [Indexed: 06/10/2023]
Abstract
This corrects the article DOI: 10.1103/PhysRevE.99.062702.
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Dolganov PV, Shuravin NS, Dolganov VK, Fukuda A. Orientational action of edge dislocations on the director field in antiferroelectric smectic-C_{A}^{*} films. Phys Rev E 2017; 95:012711. [PMID: 28208509 DOI: 10.1103/physreve.95.012711] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2016] [Indexed: 11/07/2022]
Abstract
We report imaging of the director field near edge dislocations in thermotropic antiferroelecric smectic-C_{A}^{*} (SmC_{A}^{*}) liquid crystal. Measurements were made in freestanding films with thickness from two to ten smectic layers. We find two different orientations of the molecular tilt plane with respect to the edge dislocation line. The orientation is determined by the value of the Burgers vector of the dislocation. Elementary edge dislocation and dislocations with a Burgers vector equal to an odd number of layers orient the tilt plane perpendicular on the two sides of the dislocation. Dislocations with a Burgers vector equal to an even number of layers orient the molecular tilt plane parallel to the dislocation line. Difference in the orientation for an odd Burgers vector can be attributed to breaking of antiferroelectric symmetry by the edge dislocation.
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Affiliation(s)
- P V Dolganov
- Institute of Solid State Physics, Russian Academy of Sciences, Chernogolovka, Moscow Region 142432, Russia
| | - N S Shuravin
- Institute of Solid State Physics, Russian Academy of Sciences, Chernogolovka, Moscow Region 142432, Russia.,Moscow Institute of Physics and Technology, Dolgoprudny, Moscow Region 141700, Russia
| | - V K Dolganov
- Institute of Solid State Physics, Russian Academy of Sciences, Chernogolovka, Moscow Region 142432, Russia
| | - Atsuo Fukuda
- Trinity College, Department of Electronic and Electrical Engineering, University of Dublin, Dublin 2, Ireland
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Dolganov PV, Zhilin VM, Dolganov VK, Kats EI. Field-induced transitions between multilayer phases of polar smectic liquid crystals. Phys Rev E Stat Nonlin Soft Matter Phys 2012; 86:020701. [PMID: 23005711 DOI: 10.1103/physreve.86.020701] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/17/2012] [Indexed: 06/01/2023]
Abstract
Recently Wang et al. [Phys. Rev. Lett. 104, 027801 (2010)] reported the discovery of a novel multilayer phase in polar liquid crystals. The phase was unambiguously assigned to a six-layer antiferroelectric structure (Sm-C(d6)(*)) by resonant x-ray diffraction. This discovery lead to essential progress in understanding the nature of polar phases. However, more recently, Chandani et al. [Liq. Cryst. 38, 663 (2011)] in the same material clearly identified the novel phase as a ferrielectric five-layer structure (Sm-C(d5)(*)) by the electric-field-induced birefringence. This contradiction seemed to be a mystery. In this paper we show that the two experiments are in agreement. Phenomenological Landau theory of the phase transitions shows that both phases (Sm-C(d6)(*) and Sm-C(d5)(*)) exist and transform into each other in a relatively low electric field.
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Affiliation(s)
- P V Dolganov
- Institute of Solid State Physics, Russian Academy of Sciences, 142432 Chernogolovka, Moscow Region, Russia
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Dolganov PV, Zhilin VM, Dolganov VK, Kats EI. Manifold of polar smectic liquid crystals with spatial modulation of the order parameter. Phys Rev E 2011; 83:061705. [PMID: 21797385 DOI: 10.1103/physreve.83.061705] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2011] [Revised: 04/27/2011] [Indexed: 11/06/2022]
Abstract
We revisit a theoretical approach based on the discrete Landau model of polar smectic liquid crystals. Treating equilibrium structures on many length scales, we have analyzed different periodically modulated polar smectic phases. Besides already known smectic structures, we have obtained a number of other phases which are stable in a narrow range (that is why the phases can be termed as microphases) of model parameters and thermodynamic conditions. The sequence of microphases represents a so-called "harmless staircase" of structures with oscillating periods. We anticipate that the range of stabilities for various microphases can be extended (and therefore the microphases can be easier to detect experimentally) by applying external electric fields or/and investigating freestanding smectic films.
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Affiliation(s)
- P V Dolganov
- Institute of Solid State Physics Russian Academy of Sciences, Chernogolovka, Moscow Region, Russia
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Dolganov PV, Zhilin VM, Dolganov VK, Kats EI. Commensurate polar smectic structures with a two-component order parameter. Phys Rev E 2011; 82:040701. [PMID: 21230230 DOI: 10.1103/physreve.82.040701] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2010] [Indexed: 11/07/2022]
Abstract
Recently Wang [Phys. Rev. Lett. 104, 027801 (2010)] discovered a novel smectic-C* liquid-crystal commensurate structure with six-layer period. Challenged by this discovery, we show that the observed novel structure and the unusual sequence of polar phases can be explained in the framework of the discrete Landau model of phase transitions with a two-component order parameter. Peculiarities of the six-layer phase and the influence of short-range and long-range interactions on the formation of different phases and phase sequences are discussed.
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Affiliation(s)
- P V Dolganov
- Institute of Solid State Physics RAS, 142432 Chernogolovka, Moscow district, Russia
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Dolganov PV, Nguyen HT, Joly G, Dolganov VK, Cluzeau P. Different mechanisms of nucleation and self-organization of droplets in ferroelectric smectic membranes. Eur Phys J E Soft Matter 2008; 25:31-37. [PMID: 18264663 DOI: 10.1140/epje/i2007-10261-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/12/2007] [Accepted: 12/20/2007] [Indexed: 05/25/2023]
Abstract
New mechanisms of droplet nucleation and self-organization in ferroelectric membranes are described. The droplets may be accompanied by different number of topological defects (zero, one, two) whose location may be on the droplet boundary or in the membrane. Nucleation and self-organization of droplets with total topological charge S = 0 , S = + 1 and S = - 1 were investigated. We found that an S = - 1 topological defect may be the center of both droplet nucleation and chain formation. This mechanism of chaining drastically differs from the droplet self-organization described earlier which is realized by attraction of droplet-defect pairs. Our observations demonstrate new possibilities for manipulating the inclusions and their self-organization in smectic membranes.
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Affiliation(s)
- P V Dolganov
- Institute of Solid State Physics, Russian Academy of Sciences, 142432, Chernogolovka, Moscow district, Russia.
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Dolganov PV, Nguyen HT, Kats EI, Dolganov VK, Cluzeau P. Rearrangement of topological defects and anchoring on the inclusion boundary in ferroelectric smectic membranes. Phys Rev E Stat Nonlin Soft Matter Phys 2007; 75:031706. [PMID: 17500710 DOI: 10.1103/physreve.75.031706] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/17/2006] [Indexed: 05/15/2023]
Abstract
We report experiments on a ferroelectric membrane and droplets with tunable surface properties. In smectic membranes the configuration of the c -director field near inclusions may be rearranged drastically with temperature. The transformation of the c -director field results from the competition between the elastic and polar properties of the membranes. We demonstrate that anchoring conditions on the inclusion boundary are not fixed but depend on the temperature. A dipolar c -director configuration near droplets can evolve to a mixed configuration and to a quadrupolar one. These modifications of the c -director field near the inclusions lead to a change of the interaction between the inclusions, their self-organization, and even to the destruction of structures already formed by the inclusions. Our observations open new possibilities for manipulating inclusions and controlling their self-organization.
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Affiliation(s)
- P V Dolganov
- Institute of Solid State Physics, Russian Academy of Sciences, 142432 Chernogolovka, Moscow District, Russia
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Dolganov PV, Dolganov VK. Director configuration and self-organization of inclusions in two-dimensional smectic membranes. Phys Rev E Stat Nonlin Soft Matter Phys 2006; 73:041706. [PMID: 16711826 DOI: 10.1103/physreve.73.041706] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/03/2005] [Revised: 01/24/2006] [Indexed: 05/09/2023]
Abstract
The behavior of isolated inclusions (nematic droplets, smectic islands) and formation of chains and clusters from inclusions in oriented smectic membranes have been studied. Investigations of inclusions were performed in membranes in which the molecular ordering was oriented by an external magnetic field. At planar boundary conditions on the interface between the membrane and inclusions different configurations of the c-director field were observed: Coulombic, dipolar, quadrupolar, and mixed. The observed orientation of inclusions and their interactions and self-organization correlate with the predictions of the theory based on the electromagnetic analogy. Chaining and formation of superstructures differ in oriented and nonoriented membranes.
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Affiliation(s)
- P V Dolganov
- Institute of Solid State Physics, Russian Academy of Sciences, 142432 Moscow Region, Chernogolovka, Russia
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Dolganov PV, Cluzeau P, Joly G, Dolganov VK, Nguyen HT. Interaction of surfaces in smectic membranes and their instability near thinning transitions. Phys Rev E Stat Nonlin Soft Matter Phys 2005; 72:031713. [PMID: 16241466 DOI: 10.1103/physreve.72.031713] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/22/2005] [Indexed: 05/05/2023]
Abstract
We report measurements of the interaction between surfaces of the presmectic membrane above the temperature of transition to the phase without layer ordering. Investigations were performed employing cholesteric droplets embedded in the membrane in the temperature range of thinning transitions. Upon heating, the difference between the membrane tension and surface tension of the bulk sample decreases sufficiently, which leads to membrane instability. After the thinning transition, the membrane returns to a stable state with a larger value of surface interaction.
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Affiliation(s)
- P V Dolganov
- Institute of Solid State Physics, Russian Academy of Sciences, 142432 Chernogolovka, Moscow Region, Russia
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Dolganov PV, Demikhov EI, Dolganov VK, Bolotin BM, Krohn K. Collective behavior of light-induced droplets in smectic membranes. Eur Phys J E Soft Matter 2003; 12:593-597. [PMID: 15007756 DOI: 10.1140/epje/e2004-00031-6] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Collective behavior and organization of droplets in thin smectic membranes were investigated using polarized light microscopy. Droplets were nucleated in membranes by light illumination. We observed the formation of periodic hexagonal and square lattice structures from droplets at large droplet concentration. Nearly linear dependence between period of structure and droplet size was found. We observed that droplets are nucleated on dislocations and periodic chain of droplets may be formed along a dislocation.
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Affiliation(s)
- P V Dolganov
- Institute of Solid State Physics, Russian Academy of Sciences 142432 Moscow Region, Chernogolovka, Russia.
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Dolganov PV, Zhilin VM, Dolganov VK, Kats EI. Structures and phase transitions in polar smectic liquid crystals. Phys Rev E Stat Nonlin Soft Matter Phys 2003; 67:041716. [PMID: 12786386 DOI: 10.1103/physreve.67.041716] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/16/2002] [Indexed: 05/24/2023]
Abstract
A discrete phenomenological model of antiferroelectric liquid crystals is used to study the structures and phase transitions in bulk samples and thin films. An important ingredient of our investigations is minimization of the free energy with respect to the phase and modulus of the order parameter. A simple version of the free energy, which contains only the nearest-neighbor and the next-nearest-neighbor layer interactions gives a complete phase diagram with all the observed smectic-C* (SmC*) variant phases. In thin free-standing films, surface ordering may lead to suppression of the bulk SmC(*)(alpha) helix and to formation of planar structures. Transitions between these structures are accompanied by the 90 degrees reorientation of the polarization direction. We also discuss the influence of chirality on subphase structures.
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Affiliation(s)
- P V Dolganov
- Institute of Solid State Physics, Russian Academy of Sciences, 142432 Moscow Region, Chernogolovka, Russia
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Cluzeau P, Joly G, Nguyen HT, Gors C, Dolganov VK. Formation of string defects at thinning transitions in smectic-C* free-standing films. Phys Rev E Stat Phys Plasmas Fluids Relat Interdiscip Topics 2000; 62:R5899-902. [PMID: 11102010 DOI: 10.1103/physreve.62.r5899] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/16/2000] [Indexed: 11/07/2022]
Abstract
The layer thinning transitions in freely suspended smectic-C* films have been investigated. The defect structure formed by stringlike lines was observed just before the thinning transitions. The string defects disappear after the thinning transition and appear again near the temperature of the next thinning transition. These results clearly indicate that thin free-standing films at the thinning transitions are slightly below the melting temperature of the interior layers.
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Affiliation(s)
- P Cluzeau
- Laboratoire de Dynamique et de Structure des Materiaux Moleculaires, ESA CNRS 8024, Universite de Lille I, 59655 Villeneuve d'Ascq Cedex, France
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Demikhov EI, Dolganov VK, Meletov KP. Step-by-step thinning of free-standing films above the smectic-A-nematic phase transition. Phys Rev E Stat Phys Plasmas Fluids Relat Interdiscip Topics 1995; 52:R1285-R1287. [PMID: 9963650 DOI: 10.1103/physreve.52.r1285] [Citation(s) in RCA: 68] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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Dolganov VK, Fouret R, Gors C, More M. Macroscopic and local orientational orders in nematic glass. Phys Rev E Stat Phys Plasmas Fluids Relat Interdiscip Topics 1994; 49:5230-5233. [PMID: 9961847 DOI: 10.1103/physreve.49.5230] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
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Meletov KP, Dolganov VK, Zharikov OV, Kremenskaya IN, Ossipyan YA. Absorption spectra of crystalline fullerite 60 at pressures up to 19 GPa. ACTA ACUST UNITED AC 1992. [DOI: 10.1051/jp1:1992270] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
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