The Experts below are selected from a list of 263835 Experts worldwide ranked by ideXlab platform
Philippe Poulin - One of the best experts on this subject based on the ideXlab platform.
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Nematic Liquid Crystals of graphene flakes
2016Co-Authors: Camilo Zamora-ledezma, Cécile Zakri, Eric Anglaret, Philippe Poulin, Christophe BlancAbstract:Liquid crystal ordering is an opportunity to develop novel materials and applications with spontaneouslyaligned anisotropic particles [1,2]. In this way, the organization of graphene flakes in Liquid Crystals provides new methodologies for the still challenging structural characterization of such materials. In this work, we will present a review of our recent results in the preparation and characterization of lyotropic LC made from concentrated aqueous suspensions based graphene oxide (GO) and/or reduced graphene oxide (RGO), and we will show some of ours preliminary approaches to achieve large and well-ordered domains of lyotropic Liquid Crystals. According with literature, for graphene, it is known that GO flakes easily disperse in water and spontaneously form Liquid Crystals at high concentrations. However, most of their electronic functionalities are lost during the oxidation treatments. RGO is of greater interest since a large part of functionalities are recovered but chemical reduction of GO in water generally results in the aggregation of the flakes. We recently showed how to obtain water-based RGO Liquid Crystals stabilized by surfactant molecules [3]. Structural and thermodynamic characterizations provide statistical information on the dimensions of the graphene flakes, which are found to be comparable with those of neat graphene oxide flakes. We have started to combined these new Liquid Crystals with nanoparticles, these graphene-based LC/Nanoparticles composites being useful to design coatings and functional materials. References [1] Yuan J.; Luna A.; Neri W.; Zakri C.; Schilling T.; Colin A.; Poulin, P. Graphene Liquid crystal retardedpercolation for new high-k materials. Nat. Commun. 6:8700 (2015) doi: 10.1038/ncomms9700 [2] Zakri, C.; Blanc, C.; Grelet, E.; Zamora-Ledezma, C.; Puech, N.; Anglaret, E.; and Poulin, P. Liquid Crystals ofcarbon nanotubes and graphene. Phil. Trans. R. Soc. A., 371, 20120499, pp 1-15 (2013) [3] Zamora-Ledezma, C.; Puech, N.; Zakri, C.; Grelet, E.; Moulton, S. E.; Wallace, G. G.; Gambhir, S.; Blanc, C.;Anglaret, E.; and Poulin, P. Liquid Crystallinity and Dimensions of Surfactant-Stabilized Sheets of ReducedGraphene Oxide. J. Phys. Chem. Lett., 3 (17), pp 2425–2430 (2012)
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Liquid Crystals of carbon nanotubes and graphene
Philosophical Transactions of the Royal Society A, 2013Co-Authors: Cécile Zakri, Christophe Blanc, Nicolas Puech, Eric Grelet, Camilo Zamora-ledezma, Eric Anglaret, Philippe PoulinAbstract:Liquid crystal ordering is an opportunity to develop novel materials and applications with spontaneously aligned nanotubes or graphene particles. Nevertheless, achieving high orientational order parameter and large monodomains remains a challenge. In addition, our restricted knowledge of the structure of the currently available materials is a limitation for fundamental studies and future applications. This paper presents recent methodologies that have been developed to achieve large monodomains of nematic Liquid Crystals. These allow quantification and increase of their order parameters. Nematic ordering provides an efficient way to prepare conductive films that exhibit anisotropic properties. In particular, it is shown how the electrical conductivity anisotropy increases with the order parameter of the nematic Liquid crystal. The order parameter can be tuned by controlling the length and entanglement of the nanotubes. In the second part of the paper, recent results on graphene Liquid Crystals are reported. The possibility to obtain water-based Liquid Crystals stabilized by surfactant molecules is demonstrated. Structural and thermodynamic characterizations provide indirect but statistical information on the dimensions of the graphene flakes. From a general point of view, this work presents experimental approaches to optimize the use of nanocarbons as Liquid Crystals and provides new methodologies for the still challenging characterization of such materials.
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Highly Ordered Carbon Nanotube Nematic Liquid Crystals
Journal of Physical Chemistry C, 2011Co-Authors: Nicolas Puech, Christophe Blanc, Eric Grelet, Camilo Zamora-ledezma, Maryse Maugey, Cécile Zakri, Eric Anglaret, Philippe PoulinAbstract:Liquid crystal ordering is an opportunity to develop novel materials and applications with carbon nanotubes spontaneously aligned on macroscopic scales. Nevertheless, achievement of large orientational order parameter and extended monodomains remains challenging. In this work, we show that shortening nanotubes allows the formation of Liquid Crystals that can easily be oriented under the form of large macroscopic monodomains. The orientational order parameter of single-wall nanotube Liquid Crystals measured by polarized Raman spectroscopy at the isotropic-nematic transition exceeds by far the value reported in previous experiments. The presently measured order parameter approaches the value theoretically expected for Liquid Crystals made of rigid rods in solution. This finding suggests that the production of highly ordered nanotubebased Liquid Crystals was presumably limited in earlier contributions by the length and waviness of long nanotubes. Both factors increase the material viscosity, can yield some elasticity, and stabilize topological defects.
Christophe Blanc - One of the best experts on this subject based on the ideXlab platform.
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Nematic Liquid Crystals of graphene flakes
2016Co-Authors: Camilo Zamora-ledezma, Cécile Zakri, Eric Anglaret, Philippe Poulin, Christophe BlancAbstract:Liquid crystal ordering is an opportunity to develop novel materials and applications with spontaneouslyaligned anisotropic particles [1,2]. In this way, the organization of graphene flakes in Liquid Crystals provides new methodologies for the still challenging structural characterization of such materials. In this work, we will present a review of our recent results in the preparation and characterization of lyotropic LC made from concentrated aqueous suspensions based graphene oxide (GO) and/or reduced graphene oxide (RGO), and we will show some of ours preliminary approaches to achieve large and well-ordered domains of lyotropic Liquid Crystals. According with literature, for graphene, it is known that GO flakes easily disperse in water and spontaneously form Liquid Crystals at high concentrations. However, most of their electronic functionalities are lost during the oxidation treatments. RGO is of greater interest since a large part of functionalities are recovered but chemical reduction of GO in water generally results in the aggregation of the flakes. We recently showed how to obtain water-based RGO Liquid Crystals stabilized by surfactant molecules [3]. Structural and thermodynamic characterizations provide statistical information on the dimensions of the graphene flakes, which are found to be comparable with those of neat graphene oxide flakes. We have started to combined these new Liquid Crystals with nanoparticles, these graphene-based LC/Nanoparticles composites being useful to design coatings and functional materials. References [1] Yuan J.; Luna A.; Neri W.; Zakri C.; Schilling T.; Colin A.; Poulin, P. Graphene Liquid crystal retardedpercolation for new high-k materials. Nat. Commun. 6:8700 (2015) doi: 10.1038/ncomms9700 [2] Zakri, C.; Blanc, C.; Grelet, E.; Zamora-Ledezma, C.; Puech, N.; Anglaret, E.; and Poulin, P. Liquid Crystals ofcarbon nanotubes and graphene. Phil. Trans. R. Soc. A., 371, 20120499, pp 1-15 (2013) [3] Zamora-Ledezma, C.; Puech, N.; Zakri, C.; Grelet, E.; Moulton, S. E.; Wallace, G. G.; Gambhir, S.; Blanc, C.;Anglaret, E.; and Poulin, P. Liquid Crystallinity and Dimensions of Surfactant-Stabilized Sheets of ReducedGraphene Oxide. J. Phys. Chem. Lett., 3 (17), pp 2425–2430 (2012)
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Carbon nanotubes and Liquid Crystals
2013Co-Authors: Christophe BlancAbstract:Carbon nanotubes and Liquid Crystals
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Liquid Crystals of carbon nanotubes and graphene
Philosophical Transactions of the Royal Society A, 2013Co-Authors: Cécile Zakri, Christophe Blanc, Nicolas Puech, Eric Grelet, Camilo Zamora-ledezma, Eric Anglaret, Philippe PoulinAbstract:Liquid crystal ordering is an opportunity to develop novel materials and applications with spontaneously aligned nanotubes or graphene particles. Nevertheless, achieving high orientational order parameter and large monodomains remains a challenge. In addition, our restricted knowledge of the structure of the currently available materials is a limitation for fundamental studies and future applications. This paper presents recent methodologies that have been developed to achieve large monodomains of nematic Liquid Crystals. These allow quantification and increase of their order parameters. Nematic ordering provides an efficient way to prepare conductive films that exhibit anisotropic properties. In particular, it is shown how the electrical conductivity anisotropy increases with the order parameter of the nematic Liquid crystal. The order parameter can be tuned by controlling the length and entanglement of the nanotubes. In the second part of the paper, recent results on graphene Liquid Crystals are reported. The possibility to obtain water-based Liquid Crystals stabilized by surfactant molecules is demonstrated. Structural and thermodynamic characterizations provide indirect but statistical information on the dimensions of the graphene flakes. From a general point of view, this work presents experimental approaches to optimize the use of nanocarbons as Liquid Crystals and provides new methodologies for the still challenging characterization of such materials.
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Highly Ordered Carbon Nanotube Nematic Liquid Crystals
Journal of Physical Chemistry C, 2011Co-Authors: Nicolas Puech, Christophe Blanc, Eric Grelet, Camilo Zamora-ledezma, Maryse Maugey, Cécile Zakri, Eric Anglaret, Philippe PoulinAbstract:Liquid crystal ordering is an opportunity to develop novel materials and applications with carbon nanotubes spontaneously aligned on macroscopic scales. Nevertheless, achievement of large orientational order parameter and extended monodomains remains challenging. In this work, we show that shortening nanotubes allows the formation of Liquid Crystals that can easily be oriented under the form of large macroscopic monodomains. The orientational order parameter of single-wall nanotube Liquid Crystals measured by polarized Raman spectroscopy at the isotropic-nematic transition exceeds by far the value reported in previous experiments. The presently measured order parameter approaches the value theoretically expected for Liquid Crystals made of rigid rods in solution. This finding suggests that the production of highly ordered nanotubebased Liquid Crystals was presumably limited in earlier contributions by the length and waviness of long nanotubes. Both factors increase the material viscosity, can yield some elasticity, and stabilize topological defects.
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Do lamellar Liquid Crystals flow like solids?
Philosophical Magazine Letters, 2005Co-Authors: Christophe Blanc, M Kleman, C. Meyer, S. Asnacios, I. Lelidis, J.-l. MartinAbstract:The role of dislocations in the deformation or flow of lamellar-phase Liquid Crystals is critically examined in the light of two studies. In the first, dislocation climb is directly observed under a compression normal to the layers. Two regimes of climb are evidenced. In the second study, lamellar phases are sheared in a rotating rheometer. Gliding screw dislocations carry a vorticity tensor component, which counterbalances plastically the applied vorticity. The similarities and differences between dislocation processes in solid and lamellar Liquid Crystals are discussed.
Anna Baldycheva - One of the best experts on this subject based on the ideXlab platform.
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2D Material Liquid Crystals for Optoelectronics and Photonics
2018 International Conference Laser Optics (ICLO), 2018Co-Authors: Anna BaldychevaAbstract:The merging of the materials science paradigms of Liquid Crystals and 2D materials promises superb new opportunities for the advancement of the fields of optoelectronics and photonics. In this paper, we summarise the development of 2D material Liquid Crystals by two different methods: dispersion of 2D materials in a Liquid crystalline host and the Liquid crystal phase arising from dispersions of 2D material flakes in organic solvents. The properties of Liquid crystal phases that make them attractive for optoelectronics and photonics applications are discussed. The processing of 2D materials to allow for the development of 2D material Liquid Crystals is also considered. An emphasis is placed on the applications of such materials; from the development of films, fibers and membranes to display applications, optoelectronic devices and quality control of synthetic processes.
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2D material Liquid Crystals for optoelectronics and photonics
Journal of Materials Chemistry C, 2017Co-Authors: Ben T. Hogan, Evgeniya Kovalska, Monica F. Craciun, Anna BaldychevaAbstract:The merging of the materials science paradigms of Liquid Crystals and 2D materials promises superb new opportunities for the advancement of the fields of optoelectronics and photonics. In this review, we summarise the development of 2D material Liquid Crystals by two different methods: dispersion of 2D materials in a Liquid crystalline host and the Liquid crystal phase arising from dispersions of 2D material flakes in organic solvents. The properties of Liquid crystal phases that make them attractive for optoelectronics and photonics applications are discussed. The processing of 2D materials to allow for the development of 2D material Liquid Crystals is also considered. An emphasis is placed on the applications of such materials; from the development of films, fibers and membranes to display applications, optoelectronic devices and quality control of synthetic processes.
Cécile Zakri - One of the best experts on this subject based on the ideXlab platform.
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Nematic Liquid Crystals of graphene flakes
2016Co-Authors: Camilo Zamora-ledezma, Cécile Zakri, Eric Anglaret, Philippe Poulin, Christophe BlancAbstract:Liquid crystal ordering is an opportunity to develop novel materials and applications with spontaneouslyaligned anisotropic particles [1,2]. In this way, the organization of graphene flakes in Liquid Crystals provides new methodologies for the still challenging structural characterization of such materials. In this work, we will present a review of our recent results in the preparation and characterization of lyotropic LC made from concentrated aqueous suspensions based graphene oxide (GO) and/or reduced graphene oxide (RGO), and we will show some of ours preliminary approaches to achieve large and well-ordered domains of lyotropic Liquid Crystals. According with literature, for graphene, it is known that GO flakes easily disperse in water and spontaneously form Liquid Crystals at high concentrations. However, most of their electronic functionalities are lost during the oxidation treatments. RGO is of greater interest since a large part of functionalities are recovered but chemical reduction of GO in water generally results in the aggregation of the flakes. We recently showed how to obtain water-based RGO Liquid Crystals stabilized by surfactant molecules [3]. Structural and thermodynamic characterizations provide statistical information on the dimensions of the graphene flakes, which are found to be comparable with those of neat graphene oxide flakes. We have started to combined these new Liquid Crystals with nanoparticles, these graphene-based LC/Nanoparticles composites being useful to design coatings and functional materials. References [1] Yuan J.; Luna A.; Neri W.; Zakri C.; Schilling T.; Colin A.; Poulin, P. Graphene Liquid crystal retardedpercolation for new high-k materials. Nat. Commun. 6:8700 (2015) doi: 10.1038/ncomms9700 [2] Zakri, C.; Blanc, C.; Grelet, E.; Zamora-Ledezma, C.; Puech, N.; Anglaret, E.; and Poulin, P. Liquid Crystals ofcarbon nanotubes and graphene. Phil. Trans. R. Soc. A., 371, 20120499, pp 1-15 (2013) [3] Zamora-Ledezma, C.; Puech, N.; Zakri, C.; Grelet, E.; Moulton, S. E.; Wallace, G. G.; Gambhir, S.; Blanc, C.;Anglaret, E.; and Poulin, P. Liquid Crystallinity and Dimensions of Surfactant-Stabilized Sheets of ReducedGraphene Oxide. J. Phys. Chem. Lett., 3 (17), pp 2425–2430 (2012)
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Liquid Crystals of carbon nanotubes and graphene
Philosophical Transactions of the Royal Society A, 2013Co-Authors: Cécile Zakri, Christophe Blanc, Nicolas Puech, Eric Grelet, Camilo Zamora-ledezma, Eric Anglaret, Philippe PoulinAbstract:Liquid crystal ordering is an opportunity to develop novel materials and applications with spontaneously aligned nanotubes or graphene particles. Nevertheless, achieving high orientational order parameter and large monodomains remains a challenge. In addition, our restricted knowledge of the structure of the currently available materials is a limitation for fundamental studies and future applications. This paper presents recent methodologies that have been developed to achieve large monodomains of nematic Liquid Crystals. These allow quantification and increase of their order parameters. Nematic ordering provides an efficient way to prepare conductive films that exhibit anisotropic properties. In particular, it is shown how the electrical conductivity anisotropy increases with the order parameter of the nematic Liquid crystal. The order parameter can be tuned by controlling the length and entanglement of the nanotubes. In the second part of the paper, recent results on graphene Liquid Crystals are reported. The possibility to obtain water-based Liquid Crystals stabilized by surfactant molecules is demonstrated. Structural and thermodynamic characterizations provide indirect but statistical information on the dimensions of the graphene flakes. From a general point of view, this work presents experimental approaches to optimize the use of nanocarbons as Liquid Crystals and provides new methodologies for the still challenging characterization of such materials.
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Highly Ordered Carbon Nanotube Nematic Liquid Crystals
Journal of Physical Chemistry C, 2011Co-Authors: Nicolas Puech, Christophe Blanc, Eric Grelet, Camilo Zamora-ledezma, Maryse Maugey, Cécile Zakri, Eric Anglaret, Philippe PoulinAbstract:Liquid crystal ordering is an opportunity to develop novel materials and applications with carbon nanotubes spontaneously aligned on macroscopic scales. Nevertheless, achievement of large orientational order parameter and extended monodomains remains challenging. In this work, we show that shortening nanotubes allows the formation of Liquid Crystals that can easily be oriented under the form of large macroscopic monodomains. The orientational order parameter of single-wall nanotube Liquid Crystals measured by polarized Raman spectroscopy at the isotropic-nematic transition exceeds by far the value reported in previous experiments. The presently measured order parameter approaches the value theoretically expected for Liquid Crystals made of rigid rods in solution. This finding suggests that the production of highly ordered nanotubebased Liquid Crystals was presumably limited in earlier contributions by the length and waviness of long nanotubes. Both factors increase the material viscosity, can yield some elasticity, and stabilize topological defects.
Camilo Zamora-ledezma - One of the best experts on this subject based on the ideXlab platform.
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Nematic Liquid Crystals of graphene flakes
2016Co-Authors: Camilo Zamora-ledezma, Cécile Zakri, Eric Anglaret, Philippe Poulin, Christophe BlancAbstract:Liquid crystal ordering is an opportunity to develop novel materials and applications with spontaneouslyaligned anisotropic particles [1,2]. In this way, the organization of graphene flakes in Liquid Crystals provides new methodologies for the still challenging structural characterization of such materials. In this work, we will present a review of our recent results in the preparation and characterization of lyotropic LC made from concentrated aqueous suspensions based graphene oxide (GO) and/or reduced graphene oxide (RGO), and we will show some of ours preliminary approaches to achieve large and well-ordered domains of lyotropic Liquid Crystals. According with literature, for graphene, it is known that GO flakes easily disperse in water and spontaneously form Liquid Crystals at high concentrations. However, most of their electronic functionalities are lost during the oxidation treatments. RGO is of greater interest since a large part of functionalities are recovered but chemical reduction of GO in water generally results in the aggregation of the flakes. We recently showed how to obtain water-based RGO Liquid Crystals stabilized by surfactant molecules [3]. Structural and thermodynamic characterizations provide statistical information on the dimensions of the graphene flakes, which are found to be comparable with those of neat graphene oxide flakes. We have started to combined these new Liquid Crystals with nanoparticles, these graphene-based LC/Nanoparticles composites being useful to design coatings and functional materials. References [1] Yuan J.; Luna A.; Neri W.; Zakri C.; Schilling T.; Colin A.; Poulin, P. Graphene Liquid crystal retardedpercolation for new high-k materials. Nat. Commun. 6:8700 (2015) doi: 10.1038/ncomms9700 [2] Zakri, C.; Blanc, C.; Grelet, E.; Zamora-Ledezma, C.; Puech, N.; Anglaret, E.; and Poulin, P. Liquid Crystals ofcarbon nanotubes and graphene. Phil. Trans. R. Soc. A., 371, 20120499, pp 1-15 (2013) [3] Zamora-Ledezma, C.; Puech, N.; Zakri, C.; Grelet, E.; Moulton, S. E.; Wallace, G. G.; Gambhir, S.; Blanc, C.;Anglaret, E.; and Poulin, P. Liquid Crystallinity and Dimensions of Surfactant-Stabilized Sheets of ReducedGraphene Oxide. J. Phys. Chem. Lett., 3 (17), pp 2425–2430 (2012)
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Liquid Crystals of carbon nanotubes and graphene
Philosophical Transactions of the Royal Society A, 2013Co-Authors: Cécile Zakri, Christophe Blanc, Nicolas Puech, Eric Grelet, Camilo Zamora-ledezma, Eric Anglaret, Philippe PoulinAbstract:Liquid crystal ordering is an opportunity to develop novel materials and applications with spontaneously aligned nanotubes or graphene particles. Nevertheless, achieving high orientational order parameter and large monodomains remains a challenge. In addition, our restricted knowledge of the structure of the currently available materials is a limitation for fundamental studies and future applications. This paper presents recent methodologies that have been developed to achieve large monodomains of nematic Liquid Crystals. These allow quantification and increase of their order parameters. Nematic ordering provides an efficient way to prepare conductive films that exhibit anisotropic properties. In particular, it is shown how the electrical conductivity anisotropy increases with the order parameter of the nematic Liquid crystal. The order parameter can be tuned by controlling the length and entanglement of the nanotubes. In the second part of the paper, recent results on graphene Liquid Crystals are reported. The possibility to obtain water-based Liquid Crystals stabilized by surfactant molecules is demonstrated. Structural and thermodynamic characterizations provide indirect but statistical information on the dimensions of the graphene flakes. From a general point of view, this work presents experimental approaches to optimize the use of nanocarbons as Liquid Crystals and provides new methodologies for the still challenging characterization of such materials.
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Highly Ordered Carbon Nanotube Nematic Liquid Crystals
Journal of Physical Chemistry C, 2011Co-Authors: Nicolas Puech, Christophe Blanc, Eric Grelet, Camilo Zamora-ledezma, Maryse Maugey, Cécile Zakri, Eric Anglaret, Philippe PoulinAbstract:Liquid crystal ordering is an opportunity to develop novel materials and applications with carbon nanotubes spontaneously aligned on macroscopic scales. Nevertheless, achievement of large orientational order parameter and extended monodomains remains challenging. In this work, we show that shortening nanotubes allows the formation of Liquid Crystals that can easily be oriented under the form of large macroscopic monodomains. The orientational order parameter of single-wall nanotube Liquid Crystals measured by polarized Raman spectroscopy at the isotropic-nematic transition exceeds by far the value reported in previous experiments. The presently measured order parameter approaches the value theoretically expected for Liquid Crystals made of rigid rods in solution. This finding suggests that the production of highly ordered nanotubebased Liquid Crystals was presumably limited in earlier contributions by the length and waviness of long nanotubes. Both factors increase the material viscosity, can yield some elasticity, and stabilize topological defects.
