Claudine Noël
École Normale Supérieure
Network
Latest external collaboration on country level. Dive into details by clicking on the dots.
Publication
Featured researches published by Claudine Noël.
Liquid Crystals | 1986
G. Decobert; J. C. Dubois; S. Esselin; Claudine Noël
Abstract Three acrylate side-chain polymers in which the mesogenic moieties are based on the 4-n-alkoxyphenyl-4′-(4″-methylhexyloxy) benzoates have been characterized by differential scanning calorimetry, optical microscopy and X-ray diffraction. For shorter flexible spacers (n = 2) both smectic A and C* phases are observed thus making this polymer interesting for the fabrication of electro-optical devices based on ferroelectric properties (a smectic A phase is required for alignment purposes). For longer flexible spacers, (n = 6, 11) only the smectic A phase remains.
Molecular Crystals and Liquid Crystals | 1986
J. C. Dubois; Guy Decobert; Pierre Le Barny; Sophie Esselin; Claude Friedrich; Claudine Noël
Abstract Interest in liquid crystalline side-chain polymers has grown tremendously in recent years because of their theoretical aspects and their potential applications. Over the past few years, a considerable research effort has been made in electro-optic display using nematic or smectic. A mesogenic side-chain polymers. On the other hand, non linear optical effects have been obtained with a nematic side-chain copolymer doped with a molecule exhibiting an extremely large molecular hyperpolarizability β and poled with a D.C. electricfield.
Polymer Bulletin | 1986
Pierre Le Barny; Jean-Claude Dubols; Claude Friedrich; Claudine Noël
SummaryTwo acrylate side chain polymers in which the mesogenic moiety is a 4′-cyano-biphenyl-4-yl group have been synthesized and characterized by d.s.c., optical microscopy and X-ray diffraction. If the mesogenic moiety is linked to the polymer backbone by a -O-CO-(CH2)-5 group, the resultant polymer is nematic. For a -O-(CH2)-6 group, the unusual NSANre sequence is observed. X-ray diffraction has shown that the SA phase has a partially bilayer structure : the molecules are arranged in an antiparallel, overlapping interdigitated structure with a layer spacing of about 1.4 times the length of the side chains. Monolayer fluctuations are also observed in this SA phase.
Desalination | 1981
C. Friedrich; A. Driancourt; Claudine Noël; L. Monnerie
Abstract The concept of solubility parameter, developed by Hansen, has been applied to the determination of solubility diagram of polysulfone and sulfonated polysulfone. Data showing the effect of various parameters such as thermodynamic quality of the solvent, casting solution composition and viscosity, solvent evaporation period and precipitation bath composition, on membrane structure and performance have been presented. By adjusting these parameters a wide variety of sulfonated polysulfone membranes useful for both ultrafiltration and reverse osmosis applications could be obtained.
Polymer | 1984
Claudine Noël; Claude Friedrich; Françoise Lauprêtre; J. Billard; L. Bosio; C. Strazielle
Abstract Properties of a copolyester based on methylhydroquinone, pyrocatechol and terephthalic acid have been described. Light scattering data for the copolyester in chloroform and dichloroacetic acid are well represented by M w =220 000 while the intrinsic viscosity is 0.22 dl g−1, which implies a compact arrangement of the molecule in dilute solution. Differential scanning calorimetry (d.s.c.) traces show that the copolyester is essentially non-crystalline in character. Polarizing microscopy (texture observations, miscibility tests) provides definite proof as to the nematic structure of the melt. Well aligned samples can be produced either by subjecting nematic melt to a magnetic field (Hc = 0.6 T) or by suitable treatments of the slides between which the melt is observed. The conoscopic interference pattern corresponds to that of a uniaxial system showing an optically positive character. A structural model is proposed to account for the X-ray patterns obtained from oriented samples.
Molecular Crystals and Liquid Crystals | 1988
Sophie Esselin; Claudine Noël; Guy Decobert; J. C. Dubois
Abstract In the chiral smectic phase (i.e. the C phase), the molecules are arranged randomly in layers and tilted with respect to the normal layer. The symmetry plane of the ordinary smectic C structure is absent because the molecules are chiral. The only symmetry element is a twofold rotation axis which allows molecules to “flip-flop” head-to-tail. If there is any transverse electric molecular dipole moment, its component along this axis cannot be averaged to zero and so each Layer is spontaneously polarized. However, on passing from layer to layer the tilt direction of the molecules is turned through a small angle about an axis perpendicular to the layers and hence a helical structure is formed. The spontaneous polarization is rotated from one layer to the next about the helical axis and averages to zero in a bulk sample. Hence, the chiral smectic phase is ferroelectric only if the helical arrangement is suppressed.
Polymer | 1984
Claudine Noël; Françoise Lauprêtre; Claude Friedrich; B. Fayolle; L. Bosio
Details of the thermal behaviour of the following liquid-crystalline ‘backbone’ copolyester are reported: — [OCC6O]0.6+[OOCC6H4OCH2CH2OC2H4COOCH2CH2]0.4? Between 218° and 337°C, observations using a polarizing microscope indicate the formation of a birefringent melt that exhibits a Schlieren texture. From the observation of disclinations of strength ± 12, the mesophase can be identified as a nematic phase. The isobaric phase diagram of mixtures of copolyester and N,N′-di-(ρ-methoxy benzylidene)-α,α′-bi-ρ-toluidine and X-ray diffraction patterns provide definite proof as to the nematic structure of the birefringent melt. Addition of a chiral compound to the copolyester in the nematic state causes the formation of the typical textures of cholesterics. The temperature dependence of the order parameter has been determined from FTi.r. polarized spectra. At high temperature S is found to be 0.3. Such a result confirms the recent theory of Ronca and Yoon: the isotropic-nematic transition of semiflexible polymers does not entail a very high degree of order in the resultant nematic phase.
Polymer | 1984
Claudine Noël; Claude Friedrich; L. Bosio; C. Strazielle
Abstract Polyesters with the general formula: (n=1 (TO 5), 3 (TO 11), 9 (TO 29)) were characterized by differential scanning calorimetry, optical microscopy, miscibility tests and X-ray investigations. In polyesters TO 5 and TO 11 a smectic phase type C occurs. X-ray studies of oriented samples have suggested that the smectic C configuration is azimuthally disordered with the layers orientationally ordered. By contrast, above its melting point the polyester TO 29 shows distinct phases of liquid crystal and isotropic liquid. This is probably due to the polydispersity of the low molecular weight fraction of PEO used in preparing this polyester. A structural model is proposed to illustrate how the polyesters under investigation can adopt organizations compatible with all data known so far.
Polymer | 1993
S. Bensaad; B. Jasse; Claudine Noël
Abstract The orientation development that takes place during injection moulding of liquid crystalline polymer (LCP) is analysed by FT i.r. specular reflection. The LCP used is the commercial Hoechst-Celanese product Vectra B900 based on terephthalic acid, p -aminophenol and 6-hydroxy 2-naphthoic acid. Dichroic ratios were measured from the 1016 cm −1 absorption band which is associated with a vibration of the 1,4-disubstituted benzene rings. The results, which are in good agreement with previous photoacoustic measurements, show that orientation is maximum along the principal axis of the mould with two significant minima of orientation located approximately at 2 and 3.2 cm from the injection gate. Furthermore, as the sample position shifts along the transverse direction towards the mould edge, there is a marked fall-off in orientation and the orientation minima occur at positions closer to the gate.
Molecular Crystals and Liquid Crystals | 1984
P. Meurisse; F. Laupretre; Claudine Noël
Abstract PCILO conformational calculations have been carried out on several model compounds of thermotropic liquid crystalline polyesters [- OC-R1 -CO-O-R2]- where R1 = biphenyl, terphenyl and R2 = (-CH2-)3, -CH2-C(CH3)2-CH2–CH2-C(C2H5-) CH2-. The calculated structures can be compared to the X-ray crystallographic data. The conformational characteristics of the carboxyl groups are independent of the number of phenyl rings. The introduction of substituents into the flexible spacer results in a sharpening of the potential energy wells and an increase in the energy barriers.