I graduated from the University of Bordeaux (UB1, France) and received B.S. and M.S. degrees in Organic Chemistry, as well as a postgraduate degree in Polymer Chemistry.
I then conducted my doctoral research on the confinement effects into mesoporous silica and carbon nanostructures at the Intense Pulsed Neutron Source of Argonne National Laboratory (University of Chicago, USDOE) between 2003 and 2005 under the supervision of Professor M.L. Saboungi and received my Ph.D. degree in Chemistry (Materials Science) in 2006 from the University of Orleans (France).
In 2007 I joined the group of Professor J.L. Sauvajol at the University of Montpellier (UM2, France) for a postdoctoral position and I worked with Prof. J.L. Bantignies on the structural and physical properties of epoxy/functionalized carbon nanotubes composite materials.
In 2010 I joined the Advanced Technologies Laboratory Barcelona (ATLB) of Henkel AG & Co. at Universitat Autònoma de Barcelona (UAB, Spain) to work on polymer materials for adhesion applications.
HAL is a multi-disciplinary open access archive for the deposit and dissemination of sci-entific ... more HAL is a multi-disciplinary open access archive for the deposit and dissemination of sci-entific research documents, whether they are pub-lished or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L’archive ouverte pluridisciplinaire HAL, est destinée au dépôt et a ̀ la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d’enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.
"A radiation curable adhesive comprising (i) (meth)acrylic monomer(s) and/or oli... more "A radiation curable adhesive comprising (i) (meth)acrylic monomer(s) and/or oligomer(s), wherein said (meth)acrylic monomers or oligomers comprise 5 to 50 wt % of esters of (meth)acrylic acid with polyetherpolyols having the formula HO-((CH2)m-O)n-X , m = 2,3,4 ; n = 2 to 50 ; X = H, linear, branched or aromatic C1 to C12- alkyl, the ester having a molecular weight from 150 to 2000 g/mol; (ii) non-reactive (co)polymer(s) based on unsaturated monomers, wherein said unsaturated monomers are selected from vinyl esters, (meth) acrylate esters, C2 to C8 unsaturated olefins, (iso)butylene the (co)polymer having a molecular weight from 5000 g/mol to 500000g/mol, such adhesive can form a solid adhesive layer after being cross-linked by radiation, the layer has a non tacky surface but can be adhesively bonded under pressure to a second layer of the adhesive."
The main contribution for the adhesion between epoxy polymer and sulfonated polystyrene appears t... more The main contribution for the adhesion between epoxy polymer and sulfonated polystyrene appears to be an acid-base interaction/reaction rather than the previously proposed cation-π interaction, whose contribution may exist but cannot be considered dominant in the observed adhesion. Questions still remain concerning the very high tensile strength value obtained previously by for non-functionalized polystyrene and epoxy. One would have expected before the publication of GM results that no significant adhesion could be obtained considering only van der Waals force or other noncovalent interactions (CH-π, π-π, OH-π) if chain entanglement on the interface were excluded. Our own experiments consequently confirmed that no adhesion is present in this case, so the high value of 3.8 MPa is highly questionable. An epoxy polymer made of only BADGE epoxy resin and diamine curing agent in large excess gave the same result than an epoxy resin made of the same previous composition plus NGDE (or BDDE). It was possible to demonstrate that the method can work for commodity polymers (PS, SBR, and neoprene) but it requires a surface modification by a harsh acidic treatment or a lengthy two steps method.
The confinement of chalcogens is intensely studied because of the growing interest in nanostructu... more The confinement of chalcogens is intensely studied because of the growing interest in nanostructured semiconductors and the vast range of technical applications that exploit the photoconducting, thermochromic, thermoelectric or piezoelectric properties of selenium, tellurium and their compounds. The confinement within open frameworks provides a facile means of size control. The utilized matrices include crystalline molecular sieves like zeolites, the new mesoporous silicas of the MCM type, porous glasses like Vycor and the recently discovered carbon nanotubes and fullerenes.
A radiation curable adhesive comprising (i) monomer and / or oligomer or oligomers (meth) acrylic... more A radiation curable adhesive comprising (i) monomer and / or oligomer or oligomers (meth) acrylic, wherein said monomeric or oligomeric (meth) acrylic comprise from 5 to 50% by weight of esters of ( meth) acrylic polyether having the formula HO - ((CH2) mO) n, wherein m> = 2, 3, 4; n> = 2 to 50; X> = H, C1 to C12 linear, branched or aromatic, wherein the ester has a molecular weight of 150 to 2000 g / mol; (Ii) (co) polymer or (co) polymers based reactive unsaturated monomers, wherein said unsaturated monomers are selected from vinyl esters, esters of (meth) acrylate, olefins unsaturated C2 to C8 (iso) butylene and wherein the (co) polymer has a molecular weight of 5000 g / mol to 500000 g / mol.
Les proprietes physico-chimiques des materiaux confines sont modifiees parfois de maniere drastiq... more Les proprietes physico-chimiques des materiaux confines sont modifiees parfois de maniere drastique, a cause des effets quantiques apparaissant a des tailles aussi petites, mais aussi de par le confinement lui-meme. Le but des travaux effectues durant cette these est de montrer que la nature du materiau confinant et la taille des sites de confinement - autrement dit les pores ou cavites – ont une influence essentielle sur les proprietes des materiaux ou fluides confines. Nous avons ainsi tout d'abord demontre l'effet de la taille des pores de la silice mesoporeuse sur la temperature de transition de phase solide-solide d'un semi-conducteur aux proprietes de magnetoresistance exacerbees dans des conditions non-stœchiometriques, le seleniure d'argent. Il s'avere que plus les pores sont etroits, c'est-a-dire pour des diametres d'ouverture passant de 20 nm a environ 2 nm, cette temperature de transition de phase passe de 139oC a 146 oC, les forces directrices...
Composite materials made with polymer and carbon nanotubes (CNTs) are expected to have enhanced m... more Composite materials made with polymer and carbon nanotubes (CNTs) are expected to have enhanced mechanical, thermal and electrical properties, due to extraordinary properties exhibited by carbon nanotubes themselves. However due to their insolubility in common solvents, ...
Silver chalcogenides such as Ag2Se and Ag2Te are known to be non-magnetic semiconductors for temp... more Silver chalcogenides such as Ag2Se and Ag2Te are known to be non-magnetic semiconductors for temperatures below ~ 400 K, without significant magnetoresistance. Altering the stoichiometry by adding a small amount of silver, electrical resistance of Ag2+δSe and Ag2+δTe (with δ ...
Composite materials made with polymer and carbon nanotubes (CNTs) are expected to have enhanced m... more Composite materials made with polymer and carbon nanotubes (CNTs) are expected to have enhanced mechanical, thermal and electrical properties, due to extraordinary properties exhibited by carbon nanotubes themselves. However due to their insolubility in common solvents, ...
HAL is a multi-disciplinary open access archive for the deposit and dissemination of sci-entific ... more HAL is a multi-disciplinary open access archive for the deposit and dissemination of sci-entific research documents, whether they are pub-lished or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L’archive ouverte pluridisciplinaire HAL, est destinée au dépôt et a ̀ la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d’enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.
"A radiation curable adhesive comprising (i) (meth)acrylic monomer(s) and/or oli... more "A radiation curable adhesive comprising (i) (meth)acrylic monomer(s) and/or oligomer(s), wherein said (meth)acrylic monomers or oligomers comprise 5 to 50 wt % of esters of (meth)acrylic acid with polyetherpolyols having the formula HO-((CH2)m-O)n-X , m = 2,3,4 ; n = 2 to 50 ; X = H, linear, branched or aromatic C1 to C12- alkyl, the ester having a molecular weight from 150 to 2000 g/mol; (ii) non-reactive (co)polymer(s) based on unsaturated monomers, wherein said unsaturated monomers are selected from vinyl esters, (meth) acrylate esters, C2 to C8 unsaturated olefins, (iso)butylene the (co)polymer having a molecular weight from 5000 g/mol to 500000g/mol, such adhesive can form a solid adhesive layer after being cross-linked by radiation, the layer has a non tacky surface but can be adhesively bonded under pressure to a second layer of the adhesive."
The main contribution for the adhesion between epoxy polymer and sulfonated polystyrene appears t... more The main contribution for the adhesion between epoxy polymer and sulfonated polystyrene appears to be an acid-base interaction/reaction rather than the previously proposed cation-π interaction, whose contribution may exist but cannot be considered dominant in the observed adhesion. Questions still remain concerning the very high tensile strength value obtained previously by for non-functionalized polystyrene and epoxy. One would have expected before the publication of GM results that no significant adhesion could be obtained considering only van der Waals force or other noncovalent interactions (CH-π, π-π, OH-π) if chain entanglement on the interface were excluded. Our own experiments consequently confirmed that no adhesion is present in this case, so the high value of 3.8 MPa is highly questionable. An epoxy polymer made of only BADGE epoxy resin and diamine curing agent in large excess gave the same result than an epoxy resin made of the same previous composition plus NGDE (or BDDE). It was possible to demonstrate that the method can work for commodity polymers (PS, SBR, and neoprene) but it requires a surface modification by a harsh acidic treatment or a lengthy two steps method.
The confinement of chalcogens is intensely studied because of the growing interest in nanostructu... more The confinement of chalcogens is intensely studied because of the growing interest in nanostructured semiconductors and the vast range of technical applications that exploit the photoconducting, thermochromic, thermoelectric or piezoelectric properties of selenium, tellurium and their compounds. The confinement within open frameworks provides a facile means of size control. The utilized matrices include crystalline molecular sieves like zeolites, the new mesoporous silicas of the MCM type, porous glasses like Vycor and the recently discovered carbon nanotubes and fullerenes.
A radiation curable adhesive comprising (i) monomer and / or oligomer or oligomers (meth) acrylic... more A radiation curable adhesive comprising (i) monomer and / or oligomer or oligomers (meth) acrylic, wherein said monomeric or oligomeric (meth) acrylic comprise from 5 to 50% by weight of esters of ( meth) acrylic polyether having the formula HO - ((CH2) mO) n, wherein m> = 2, 3, 4; n> = 2 to 50; X> = H, C1 to C12 linear, branched or aromatic, wherein the ester has a molecular weight of 150 to 2000 g / mol; (Ii) (co) polymer or (co) polymers based reactive unsaturated monomers, wherein said unsaturated monomers are selected from vinyl esters, esters of (meth) acrylate, olefins unsaturated C2 to C8 (iso) butylene and wherein the (co) polymer has a molecular weight of 5000 g / mol to 500000 g / mol.
Les proprietes physico-chimiques des materiaux confines sont modifiees parfois de maniere drastiq... more Les proprietes physico-chimiques des materiaux confines sont modifiees parfois de maniere drastique, a cause des effets quantiques apparaissant a des tailles aussi petites, mais aussi de par le confinement lui-meme. Le but des travaux effectues durant cette these est de montrer que la nature du materiau confinant et la taille des sites de confinement - autrement dit les pores ou cavites – ont une influence essentielle sur les proprietes des materiaux ou fluides confines. Nous avons ainsi tout d'abord demontre l'effet de la taille des pores de la silice mesoporeuse sur la temperature de transition de phase solide-solide d'un semi-conducteur aux proprietes de magnetoresistance exacerbees dans des conditions non-stœchiometriques, le seleniure d'argent. Il s'avere que plus les pores sont etroits, c'est-a-dire pour des diametres d'ouverture passant de 20 nm a environ 2 nm, cette temperature de transition de phase passe de 139oC a 146 oC, les forces directrices...
Composite materials made with polymer and carbon nanotubes (CNTs) are expected to have enhanced m... more Composite materials made with polymer and carbon nanotubes (CNTs) are expected to have enhanced mechanical, thermal and electrical properties, due to extraordinary properties exhibited by carbon nanotubes themselves. However due to their insolubility in common solvents, ...
Silver chalcogenides such as Ag2Se and Ag2Te are known to be non-magnetic semiconductors for temp... more Silver chalcogenides such as Ag2Se and Ag2Te are known to be non-magnetic semiconductors for temperatures below ~ 400 K, without significant magnetoresistance. Altering the stoichiometry by adding a small amount of silver, electrical resistance of Ag2+δSe and Ag2+δTe (with δ ...
Composite materials made with polymer and carbon nanotubes (CNTs) are expected to have enhanced m... more Composite materials made with polymer and carbon nanotubes (CNTs) are expected to have enhanced mechanical, thermal and electrical properties, due to extraordinary properties exhibited by carbon nanotubes themselves. However due to their insolubility in common solvents, ...
The main contribution for the adhesion between epoxy polymer and sulfonated polystyrene appears t... more The main contribution for the adhesion between epoxy polymer and sulfonated polystyrene appears to be an acid-base interaction/reaction rather than the previously proposed cation-π interaction, whose contribution may exist but cannot be considered dominant in the observed adhesion. Questions still remain concerning the very high tensile strength value obtained previously by for non-functionalized polystyrene and epoxy. One would have expected before the publication of GM results that no significant adhesion could be obtained considering only van der Waals force or other noncovalent interactions (CH-π, π-π, OH-π) if chain entanglement on the interface were excluded. Our own experiments consequently confirmed that no adhesion is present in this case, so the high value of 3.8 MPa is highly questionable. An epoxy polymer made of only BADGE epoxy resin and diamine curing agent in large excess gave the same result than an epoxy resin made of the same previous composition plus NGDE (or BDDE). It was possible to demonstrate that the method can work for commodity polymers (PS, SBR, and neoprene) but it requires a surface modification by a harsh acidic treatment or a lengthy two steps method.
We have previously shown a method to functionalize carbon nanotubes (CNTs) surface to create a co... more We have previously shown a method to functionalize carbon nanotubes (CNTs) surface to create a covalent link with polymer matrix. In particular evidences for chemical functionalization have been demonstrated using characterization techniques such as XRD, FT Raman, TEM, XPS and NEXAFS. Two kind of polymers have been used – thermoset (epoxy) and thermoplastic (PEEK). While several attempts have been done in order to obtain a satisfying shaping method for PEEK-based composite material, mechanical and electrical tests have been performed on epoxy-based composite material, with different carbon nanotube weight fraction, and using functionalized and non-functionalized CNTs. In particular conductivity measurements have been done showing a spectacular increase in the case of composite made with 0.50 % in weight of functionalized nanotubes in epoxy.
Composite materials made with polymer and carbon nanotubes (CNTs) are expected to have enhanced m... more Composite materials made with polymer and carbon nanotubes (CNTs) are expected to have enhanced mechanical, thermal and electrical properties, due to extraordinary properties exhibited by carbon nanotubes themselves. However due to their insolubility in common solvents, homogeneous dispersion of CNTs in polymer matrix remains challenging. One way to overcome the problem is to functionalize their surface. In our work we used functionalization not only to modify solubility of nanotubes, but also to make covalent links between nanotubes surface and polymer by chemical reaction. Two kind of polymers have been used – thermoset (epoxy) and thermoplastic (PEEK) – and functionalization has been followed using different characterization techniques such as XRD, FT Raman, TEM, XPS and NEXAFS. Then mechanical and electrical tests have been performed.
Composite materials made with polymer and carbon nanotubes (CNTs) are expected to have enhanced m... more Composite materials made with polymer and carbon nanotubes (CNTs) are expected to have enhanced mechanical, thermal and electrical properties, due to extraordinary properties exhibited by carbon nanotubes themselves. However due to their insolubility in common solvents, homogeneous dispersion of CNTs in polymer matrix remains challenging. One way to overcome the problem is to functionalize their surface. In our work we used functionalization not only to modify solubility of nanotubes, but also to make covalent links between nanotubes surface and polymer by chemical reaction. Two kind of polymers have been used – thermoset (epoxy) and thermoplastic (PEEK) – and functionalization has been followed using different characterization techniques such as XRD, FT Raman, TEM, XPS and NEXAFS. Then mechanical and electrical tests have been performed. A functionalization method has been successfully applied to functionalize carbon nanotubes surface, then to graft polymer chains like SPEEK, making a composite material with covalent bond between the nanotubes and the polymer. Grafting has been evidenced using spectroscopy techniques such as NEXAFS, XPS or FT Raman. Nevertheless shaping of the PEEK/SPEEK-MWNTs composite sample in order to make mechanical or electrical measurements remains extremely difficult and so far no satisfying method has been found. However mechanical and electrical properties have been enhanced when mixing epoxy resin with functionalized carbon nanotubes. In particular it has been shown that conductivity increases drastically when nanotubes weight fraction increases.
Among many extraordinary properties, CNTs have a very high Young modulus, generally reported with... more Among many extraordinary properties, CNTs have a very high Young modulus, generally reported with a value of ~ 1 TPa, making this kind of material even stronger than diamond and carbon fiber. Moreover their very light weight makes them first choice materials for mechanical reinforcement of polymer matrices. Most of previous studies using CNTs deal with so-called physical mixing, meaning that there is no strong link between polymer and nanotube surface, resulting in a relatively poor enhancement of the composite Young’s modulus. In our study, we first investigated the functionalization of multi-walled carbon nanotubes (MWNTs) surface by sulfonated poly (ether ether ketone) SPEEK chains using a direct attachment reaction, PEEK being known as a very promising polymer especially in aerospace field for its particularly high glass transition and melting temperature, compared with most of polymer material.[1] MWNTs were oxidized by a nitric acid treatment to generate carboxyl groups on their surface, which then react with sulfonated groups of SPEEK using hexane diamine as an interlinking molecule.[2,3] Evidence of covalent functionalization of MWNTs by SPEEK macromolecules was given by near-edge X-ray absorption fine structure spectroscopy (NEXAFS) at the C K-edge, O K-edge, and N K-edge and X-ray photoelectron spectroscopy (XPS). Mechanical properties of the MWNT-SPEEK composite material were then tested to quantify the enhancement of Young’s modulus.
Among many extraordinary properties, Carbon nanotubes (CNTs) have a very high Young modulus, gene... more Among many extraordinary properties, Carbon nanotubes (CNTs) have a very high Young modulus, generally reported with a value of ~ 1 TPa, making this kind of material even stronger than diamond and carbon fiber. Moreover their very light weight makes them first choice materials for mechanical reinforcement of polymer matrices. Most of previous studies using CNTs deal with so-called physical mixing, meaning that there is no strong link between polymer and nanotube surface, resulting in a relatively poor enhancement of the composite Young’s modulus. In our study, we first investigated the functionalization of multi-walled carbon nanotubes (MWNTs) surface by sulfonated poly (ether ether ketone) (SPEEK) chains using a direct attachment reaction, PEEK being known as a very promising polymer especially in aerospace field for its particularly high glass transition and melting temperature, compared with most of polymer material. MWNTs were oxidized by a nitric acid treatment to generate carboxyl groups on their surface, which then react with sulfonated groups of SPEEK using hexane diamine as an interlinking molecule. Characterization of covalent functionalization of MWNTs by SPEEK macromolecules was obtained by electron microscopy, infra-red spectroscopy and near-edge X-ray absorption fine structure spectroscopy (NEXAFS) at O K-edge. Mechanical properties of the MWNT-SPEEK composite material have to be tested to quantify the enhancement of Young’s modulus.
Single-walled carbon nanohorns (SWNH) are graphitic structures formed out of a single-walled grap... more Single-walled carbon nanohorns (SWNH) are graphitic structures formed out of a single-walled graphene sheet with an average size of 2-3 nm. They adopt a horn-like shape and aggregate to form flower-like structures with sizes of about 80 - 100 nm. These nanostructures exhibit very large surface areas [1] and are therefore attractive candidates for gas and liquid storage [2]. Moreover, no metal catalyst is required for their synthesis thus enabling low-cost, large-scale production of high-purity samples. In the present work, the effects of confining olecular hydrogen within SWNHs are studied via high-resolution quasielastic and inelastic neutron spectroscopies. Both sets of data are remarkably different from those obtained in bulk samples in the liquid and crystalline states. At temperatures where bulk hydrogen is liquid, the spectra of the confined sample show an elastic component indicating a significant proportion of immobile molecules as well as distinctly narrower quasielastic line widths and a strong distortion of the line shape of the para-ortho rotational transition. The results show that hydrogen binds far more strongly to these carbonous structures than it does to carbon nanotubes, suggesting that SWNHs and related nanostructures may offer significantly better prospects as light-weight media for hydrogen storage aplications. References [1] H. Wang et al., Nanotechnology 15, 546 (2004); D. Kasuya et al., J. Phys. Chem. B 106, 4947 (2002). [2] V. Leon, Ph.D. Thesis, Univ Orleans (France) 2006; P. Kowalczyk et al., J. Phys. Chem. B 109, 14174 (2005); R.A. Trasca et al., Phys. Rev. B 67, 035410 (2003).
Silver chalcogenides such as Ag2Se and Ag2Te are known to be non-magnetic semiconductors for temp... more Silver chalcogenides such as Ag2Se and Ag2Te are known to be non-magnetic semiconductors for temperatures below ~ 400 K, without significant magnetoresistance. Altering the stoichiometry by adding a small amount of silver, electrical resistance of Ag2+δSe and Ag2+δTe (with δ = 0.01) become very sensitive to magnetic field up to 60 Teslas. Furthermore, this giant magnetoresistance presents a near-linear increase of the resistance with the applied magnetic field, without saturation. Thus silver chalcogenides appear to be attractive as magnetic-field sensors. Our work is to confine this kind of material in an inorganic matrix to make a composite material. The choice of mesoporous silica is the most appropriate one since silica is chemically inert and it presents an ordered array of interconnected pores with a diameter of about 2 nm. The method used to confine nanosized Ag2Se inside silica is the synthesis of silver chalcogenide directly inside the pores. Using synchrotron radiation X-ray diffraction we studied the effect of confinement on the β-α phase transition of Ag2Se characterizing a change of structure, from orthorhombic at low temperature to cubic at a temperature above 400 K, leading to a superionic behavior.
In the last decade there was a great interest in the investigation of interaction of hydrogen gas... more In the last decade there was a great interest in the investigation of interaction of hydrogen gas with different carbon nano-materials. Molecular hydrogen adsorbed in fullerenes, single wall carbon nanotubes (SWNT), carbon nano-fibers, etc. as well as chemically bound hydrogen were studied by different methods in order to get information on the properties of the adsorbed hydrogen and to develop an effective hydrogen storage material. The first publications on hydrogen storage in SWNT estimated a possible high hydrogen storage capacity for purified tubes at room temperature and ambient pressure. However further intense studies on a variety of nanocarbons showed variety of results that were often nonreproducible by independent measurements. Critical reviews have identified the major factor underlying the discrepancy, besides sample impurity, to be the lack of fundamental understanding of the local configurations of the adsorbed hydrogen and its physical/electronic interactions with the nanostructure environment. The most direct and complete information on hydrogen adsorption can be obtained by using inelastic neutron scattering (INS) method, because of very high neutron scattering cross-section of hydrogen (82.02 barns) compared to carbon (5.55 barns) atoms. Also, neutrons can easily penetrate different sample-container and environment walls that make possible to do INS experiments in situ, during charging/discharging the sample with hydrogen under high pressure at low or high temperatures. Up to now INS was mainly used for investigation of hydrogen uptake in pure SWNT. In this work we present INS study of hydrogen adsorption/desorption behavior in a variety carbon nano-materials.
Silver chalcogenides such as Ag2Se and Ag2Te are known to be non-magnetic semiconductors for temp... more Silver chalcogenides such as Ag2Se and Ag2Te are known to be non-magnetic semiconductors for temperatures below ~400K, without significant magnetoresistance. Altering the stoichiometry by adding a small amount of silver, electrical resistance of Ag2+δSe and Ag2+δTe (with δ = 0.01) become very sensitive to magnetic field up to 60 Teslas. Furthermore, this giant magnetoresistance presents a near-linear increase of the resistance with the applied magnetic field, without saturation. Thus silver chalcogenides appear to be attractive as magnetic-field sensors. Our work is to confine this kind of material in an inorganic matrix to make a composite material. The choice of silica is the most appropriate since silica is chemically inert and it has been shown in the case of selenium based particles that interactions between silica and selenium are very weak and that confinement preserves their semi-conducting properties. The method we have used to confine nanoparticles inside silica is the synthesis of silver chalcogenide directly inside the pores of mesoporous silica, presenting an ordered array of pores, with a diameter of about 2 nm. In the case of Ag2Se, after impregnation of a silver ions solution into silica, a selenium ions solution is introduced. The existence of nanocrystalline silver selenide has been confirmed using synchrotron radiation X-ray diffraction. The observed diffraction peaks correspond well to the standard powder diffraction data set of the orthorhombic structure of Ag2Se.
The confinement of chalcogens is intensely studied because of the growing interest in nanostructu... more The confinement of chalcogens is intensely studied because of the growing interest in nanostructured semiconductors and the vast range of technical applications that exploit the photoconducting, thermochromic, thermoelectric or piezoelectric properties of selenium, tellurium and their compounds. The confinement within open frameworks provides a facile means of size control. The utilized matrices include crystalline molecular sieves like zeolites, the new mesoporous silicas of the MCM type, porous glasses like Vycor and the recently discovered carbon nanotubes and fullerenes.
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Papers by Vincent Leon
While several attempts have been done in order to obtain a satisfying shaping method for PEEK-based composite material, mechanical and electrical tests have been performed on epoxy-based composite material, with different carbon nanotube weight fraction, and using functionalized and non-functionalized CNTs. In particular conductivity measurements have been done showing a spectacular increase in the case of composite made with 0.50 % in weight of functionalized nanotubes in epoxy.
In our work we used functionalization not only to modify solubility of nanotubes, but also to make covalent links between nanotubes surface and polymer by chemical reaction. Two kind of polymers have been used – thermoset (epoxy) and thermoplastic (PEEK) – and functionalization has been followed using different characterization techniques such as XRD, FT Raman, TEM, XPS and NEXAFS. Then mechanical and electrical tests have been performed.