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(252) Production(s) de BLANC C.
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Synthesis via ATRP and Anchoring Properties of Ammonium-Terminated Monofunctional or Telechelic Polystyrenes 
Auteur(s): Toquer Guillaume, Monge Sophie , Antonova Krassimira, Blanc C., Nobili M., Robin Jean-Jacques
(Article) Publié:
Macromolecular Chemistry And Physics, vol. 208 p.94-102 (2007)
Texte intégral en Openaccess : 
Ref HAL: hal-00181383_v1
DOI: 10.1002/macp.200600475
WoS: 000244258300012
Exporter : BibTex | endNote
13 Citations
Résumé: Mono- and di-(trimethylammonium)-terminated polystyrenes with similar molar masses were synthesized. Bromopolystyrenes were first prepared by atom transfer radical polymerization (ATRP) using (N-Boc-propylamino)-2-bromoisobutyrate as initiator and Cu(I)Br/2,2-bipyridine as catalytic system in bulk at 110 °C. ,-Telechelic polymer with double molecular weight with respect to the starting polystyrene was then obtained under atom transfer radical coupling process using 2,2-bipyridine and copper(0) mediated reductive conditions in anisole. Final (trimethylammonium)-terminated polystyrenes were eventually obtained after removal of the tert-butyloxycarbonyl group and permethylation reactions. Intermediate and final polymers were characterized by 1H NMR. The aligning properties of the obtained polymers for liquid crystals have been investigated. Pretilt and zenithal anchorings on ITO/glass substrates were measured. Finally, the possibility for the telechelic polystyrene to form a network in an inverted microemulsion was also considered.
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Optical and confocal microscopy observations of screw dislocations in smectic-A liquid crystals
Auteur(s): Lelidis I., Blanc C., Kléman M.
(Article) Publié:
European Physical Education Review, vol. 74 p.051710 (2006)
Ref HAL: hal-01208105_v1
PMID 17279929
DOI: 10.1103/PhysRevE.74.051710
WoS: 000242408700067
Exporter : BibTex | endNote
10 Citations
Résumé: We present experimental evidence of the presence of isolated screw dislocations in smectic-A liquid crystals observed by polarizing microscopy. In a wedge-shaped homeotropic cell, the edge and screw dislocations interaction gives rise to a strong-enough optical contrast and makes visible their mutual intersections at temperatures close to the smectic-A to smectic-C phase transition temperature. The nature of the defects is confirmed by confocal microscopy observations. At large scale we observe a forest of screw dislocations, perpendicular to the smectic layers, across the thickness of the cell (end-on configuration). Their density varies between 109 and 1012m−2. In situ observations of dislocations under stress, in the optical microscope, provide quantitative information about the screw-edge dislocation interactions. The latter interaction is calculated in the unharmonic approximation and it gives rise to an observed yield stress.
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Anchoring and gliding of easy axis of 5CB on photoaligning PVCN-F surface
Auteur(s): Buluy O., Iljin A., Ouskova E., Reznikov Yu., Blanc C., Nobili M., Antonova K.
(Article) Publié:
Journal Of The Society For Information Display, vol. 14 p.603 (2006)
Texte intégral en Openaccess :
Ref HAL: hal-01208122_v1
DOI: 10.1889/1.2235686
WoS: 000244853200005
Exporter : BibTex | endNote
18 Citations
Résumé: Abstract— The photoaligning properties of the popular photoaligning material polyvinyl-4(fluorocinnamate) (PVCN-F) are presented. The aligning quality and azimuthal and zenithal anchoring energy were measured and the drift of the easy orientation axis (gliding effect) on the PVCN-F surface, depending on UV exposure, was studied. Special attention is paid to unraveling the contribution of the adsorption liquid-crystal molecules onto the aligning surface to the anchoring properties of PVCNF and measuring the drift of the easy orientation axis over the PVCN-F surface. It is shown that a relatively weak azimuthal anchoring energy (Waz ∼ 10−7 − 10−5 J/m2) leads to strong drift of the easy axis in the azimuthal plane that was observed in a moderate (∼0.1–0.3 T) magnetic field. A much stronger polar anchoring (Wzen ∼ 10−4 J/m2) allowed us to observe the essential gliding of the easy axis in the zenithal plane in a rather strong electric field (∼5 V/μm).
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Unusual X-ray signature of the antiferroelectric phase in a dimesogenic liquid crystal siloxane
Auteur(s): Goc F., Blanc C., Lorman V., Kuczynski W., Nobili M., Samaritani S., Galli G.
Conference: 21 th International liquid crystal conference (Keystone, FR, 2006-07-02)
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Anchoring and gliding of a nematic liquid crystal on photoaligned PVCN-F surfaces
Auteur(s): Buluy O, Iljin A., Ouskova E., Reznikov Y., Blanc C., Nobili M., Antonova K.
Conference: 21 th International Liquid Crystal Conference (Keystone, US, 2006-07-02)
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Dynamics of nematic disclinations under an external force
Auteur(s): Blanc C., Svensek D., Zumer S., Nobili M.
Conference: 21 th International Liquid Crystal Conference (Keystone, US, 2006-07-02)
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Lyotropic mesophases in the thermotropic 5CB liquid crystal
Auteur(s): Toquer Guillaume, Porte Grégoire, Nobili M., Appell Jacqueline, Blanc C.
Conference: 21 th International Liquid Crystal Conference (Keystone, USA, FR, 2006-07-02)
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