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Philippe Dubois - One of the best experts on this subject based on the ideXlab platform.

  • plasticized polylactide organo clay nanocomposites by in Situ Intercalative Polymerization
    Macromolecular Chemistry and Physics, 2005
    Co-Authors: Marieamelie Paul, Michael Alexandre, Cecile Delcourt, Philippe Degee, Fabien Monteverde, A Rulmont, Philippe Dubois
    Abstract:

    Both intercalated and exfoliated poly(L,L-lactide) (P(L,L-LA)/organomodified montmorillonite nanocomposites were synthesized by in Situ ring-opening Polymerization of L,L-lactide, in bulk, directly in the presence of the nano-filler. Intercalation of polyester chains was found to appear even for natural unmodified montmorillonite-Na + , while exfoliation occurred when the aluminosilicate layers were modified by ammonium cations bearing primary hydroxyl groups. Clay delamination was effectively triggered by the grafting reaction of the growing PLA chains onto the hydroxyl groups. Aluminium triisopropoxide, triethylaluminium, and stannous octoate, as initiating or co-initiating species, were compared in terms of Polymerization control. The influence of nanoclay content (from 1 to 10 wt.-% in inorganics) on morphology and thermal behavior was also studied. In parallel, a highly filled nanocomposite (called master-batch), prepared by in Situ Polymerization, was dispersed into a (plasticized) preformed polylactide matrix in the molten state, to reach a better clay delamination than that obtained by direct melt blending. Finally, L,L-lactide and α,ω-dihydroxylated poly(ethylene glycol) (PEG 1000) were copolymerized in presence of clay in order to study the behavior of the resulting triblocks towards nanocomposite formation.

  • Surface Characterization of Poly(ε-caprolactone)-Based Nanocomposites
    Langmuir, 2003
    Co-Authors: Pascal Viville, Michael Alexandre, Philippe Dubois, Roberto Lazzaroni, Eric Pollet, G. Borcia, Jean-jacques Pireaux
    Abstract:

    This work deals with the preparation and the surface characterization of biodegradable nanocomposites made of poly(e-caprolactone) (PCL) and a montmorillonite-type clay. Nanocomposites with different relative compositions of PCL and montmorillonite, either natural or organo-modified by various alkylammonium cations, are prepared by melt intercalation and in Situ Intercalative Polymerization. The goal of this study is to characterize the dispersion of the clay layers in PCL, which is a critical parameter governing the final physical properties of the obtained nanocomposites. Morphological studies of PCL nanocomposites are carried out by means of scanning probe microscopy techniques while surface analysis is performed both by X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy. The results demonstrate that the dispersion of the clay layers is strongly dependent on both the synthetic route and the type of alkylammonium chains used for the cationic exchange. Whereas the melt-intercala...

  • poly epsilon caprolactone clay nanocomposites by in Situ Intercalative Polymerization catalyzed by dibutyltin dimethoxide
    Macromolecules, 2002
    Co-Authors: Bénédicte Lepoittevin, Michael Alexandre, Nadège Pantoustier, Myriam Devalckenaere, Dana Kubies, Cédric Calberg, Robert Jérôme, Philippe Dubois
    Abstract:

    Poly(e-caprolactone)/clay nanocomposites were prepared by in-Situ ring-opening Polymerization of e-caprolactone by using dibutyltin dimethoxide as an initiator/catalyst. A nonmodified Na+−montmorillonite and two montmorillonites surface-modified by dimethyl 2-ethylhexyl (hydrogenated tallow alkyl) and methyl bis(2-hydroxyethyl) (hydrogenated tallow alkyl) ammonium cations, respectively, were used. The evolution of molecular weights was followed in relation to silicate surface modification and clay concentration. The alcohol-bearing organo-modified clay was a co-initiator for the Polymerization reaction and thus controlled the molecular weight of the PCL chains. Furthermore, the number-average molecular weight of the growing PCL chains linearly increased with the monomer conversion. Nanocomposites were analyzed by small-angle X-ray diffraction, transmission electron microscopy, and thermogravimetry. The clay dispersion depended on the structure of the alkylammonium used to make the clay more hydrophobic. E...

  • Poly(epsilon-caprolactone)/clay nanocomposites by in-Situ Intercalative Polymerization catalyzed by dibutyltin dimethoxide
    Macromolecules, 2002
    Co-Authors: Bénédicte Lepoittevin, Michael Alexandre, Nadège Pantoustier, Myriam Devalckenaere, Dana Kubies, Cédric Calberg, Robert Jérôme, Philippe Dubois
    Abstract:

    Poly(epsilon-caprolactone)/clay nanocomposites were prepared by in-Situ ring-opening Polymerization of epsilon-caprolactone by using dibutyltin dimethoxide as an initiator/catalyst. A nonmodified Na+-montmorillonite and two montmorillonites surface-modified by dimethyl 2-ethylhexyl (hydrogenated tallow alkyl) and methyl bis(2-hydroxyethyl) (hydrogenated tallow alkyl) ammonium cations, respectively, were used. The evolution of molecular weights was followed in relation to silicate surface modification and clay concentration. The alcohol-bearing organo-modified clay was a co-initiator for the Polymerization reaction and thus controlled the molecular weight of the PCL chains. Furthermore, the number-average molecular weight of the growing PCL chains linearly increased with the monomer conversion. Nanocomposites were analyzed by small-angle X-ray diffraction, transmission electron microscopy, and thermogravimetry. The clay dispersion depended on the structure of the alkylammonium used to make the clay more hydrophobic. Exfoliated nanocomposites were formed when hydroxyl-containing alkylammonium. was used; otherwise, intercalated structures were reported. Thermogravimetric analyses showed a higher degradation temperature for the exfoliated structures than for the intercalated ones, both of them exceeding the degradation temperature of unfilled poly(epsilon-caprolactone).Peer reviewe

  • Polyethylene-layered silicate nanocomposites prepared by the Polymerization-filling technique: synthesis and mechanical properties
    Polymer, 2002
    Co-Authors: Michael Alexandre, Philippe Dubois, Tao Sun, Juan M. Garces, Robert Jérôme
    Abstract:

    Polyethylene-layered silicate nanocomposites were prepared by the in Situ Intercalative Polymerization of ethylene by the so-called Polymerization-filling technique and analyzed by transmission electron microscopy (TEM), X-ray diffraction analysis (XRD), differential scanning calorimetry, dynamic mechanical analysis and tensile testing. Non-modified montmorillonite and hectorite were first treated by trimethylaluminum-depleted methylaluminoxane before being contacted by a Ti-based constrained geometry catalyst. The nanocomposite was formed by addition and Polymerization of ethylene. In the absence of a chain transfer agent, ultra high molecular weight polyethylene was produced. The tensile properties of these nanocomposites were poor and essentially independent of the nature and content of the silicate. Upon hydrogen addition, the molecular weight of the polyethylene was decreased with parallel improvement of the tensile and shear moduli, in relation to the filler content. The exfoliation of the layered silicates was confirmed by XRD analysis and TEM observation. The mechanical kneading of the molten nanocomposites resulted in the partial collapse of the exfoliated structure driven by the thermodynamic stability of the layered filler.

Michael Alexandre - One of the best experts on this subject based on the ideXlab platform.

  • synthesis of polylactide clay nanocomposites by in Situ Intercalative Polymerization in supercritical carbon dioxide
    European Polymer Journal, 2009
    Co-Authors: Laetitia Urbanczyk, Michael Alexandre, Fred Ngoundjo, Christine Jerome, Christophe Detrembleur, Cédric Calberg
    Abstract:

    Abstract Polylactide (PLA)/clay nanocomposites have been prepared by in Situ ring-opening Polymerization in supercritical carbon dioxide. Depending on the type of organoclay used, polylactide chains can be grafted onto the clay surface, leading to an exfoliated morphology. Nanocomposites with high clay contents (30–50 wt.%), called masterbatches, have also been successfully prepared and were recovered as fine powders thanks to the unique properties of the supercritical fluid. Dilution of these masterbatches into commercial l -polylactide by melt blending has led to essentially exfoliated nanocomposites containing 3 wt.% of clay. The mechanical properties of these materials have been assessed by flexion and impact tests. Significant improvements of stiffness and toughness have been observed for the PLA/clay nanocomposites compared to the pure matrix, together with improved impact resistance.

  • plasticized polylactide organo clay nanocomposites by in Situ Intercalative Polymerization
    Macromolecular Chemistry and Physics, 2005
    Co-Authors: Marieamelie Paul, Michael Alexandre, Cecile Delcourt, Philippe Degee, Fabien Monteverde, A Rulmont, Philippe Dubois
    Abstract:

    Both intercalated and exfoliated poly(L,L-lactide) (P(L,L-LA)/organomodified montmorillonite nanocomposites were synthesized by in Situ ring-opening Polymerization of L,L-lactide, in bulk, directly in the presence of the nano-filler. Intercalation of polyester chains was found to appear even for natural unmodified montmorillonite-Na + , while exfoliation occurred when the aluminosilicate layers were modified by ammonium cations bearing primary hydroxyl groups. Clay delamination was effectively triggered by the grafting reaction of the growing PLA chains onto the hydroxyl groups. Aluminium triisopropoxide, triethylaluminium, and stannous octoate, as initiating or co-initiating species, were compared in terms of Polymerization control. The influence of nanoclay content (from 1 to 10 wt.-% in inorganics) on morphology and thermal behavior was also studied. In parallel, a highly filled nanocomposite (called master-batch), prepared by in Situ Polymerization, was dispersed into a (plasticized) preformed polylactide matrix in the molten state, to reach a better clay delamination than that obtained by direct melt blending. Finally, L,L-lactide and α,ω-dihydroxylated poly(ethylene glycol) (PEG 1000) were copolymerized in presence of clay in order to study the behavior of the resulting triblocks towards nanocomposite formation.

  • Surface Characterization of Poly(ε-caprolactone)-Based Nanocomposites
    Langmuir, 2003
    Co-Authors: Pascal Viville, Michael Alexandre, Philippe Dubois, Roberto Lazzaroni, Eric Pollet, G. Borcia, Jean-jacques Pireaux
    Abstract:

    This work deals with the preparation and the surface characterization of biodegradable nanocomposites made of poly(e-caprolactone) (PCL) and a montmorillonite-type clay. Nanocomposites with different relative compositions of PCL and montmorillonite, either natural or organo-modified by various alkylammonium cations, are prepared by melt intercalation and in Situ Intercalative Polymerization. The goal of this study is to characterize the dispersion of the clay layers in PCL, which is a critical parameter governing the final physical properties of the obtained nanocomposites. Morphological studies of PCL nanocomposites are carried out by means of scanning probe microscopy techniques while surface analysis is performed both by X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy. The results demonstrate that the dispersion of the clay layers is strongly dependent on both the synthetic route and the type of alkylammonium chains used for the cationic exchange. Whereas the melt-intercala...

  • poly epsilon caprolactone clay nanocomposites by in Situ Intercalative Polymerization catalyzed by dibutyltin dimethoxide
    Macromolecules, 2002
    Co-Authors: Bénédicte Lepoittevin, Michael Alexandre, Nadège Pantoustier, Myriam Devalckenaere, Dana Kubies, Cédric Calberg, Robert Jérôme, Philippe Dubois
    Abstract:

    Poly(e-caprolactone)/clay nanocomposites were prepared by in-Situ ring-opening Polymerization of e-caprolactone by using dibutyltin dimethoxide as an initiator/catalyst. A nonmodified Na+−montmorillonite and two montmorillonites surface-modified by dimethyl 2-ethylhexyl (hydrogenated tallow alkyl) and methyl bis(2-hydroxyethyl) (hydrogenated tallow alkyl) ammonium cations, respectively, were used. The evolution of molecular weights was followed in relation to silicate surface modification and clay concentration. The alcohol-bearing organo-modified clay was a co-initiator for the Polymerization reaction and thus controlled the molecular weight of the PCL chains. Furthermore, the number-average molecular weight of the growing PCL chains linearly increased with the monomer conversion. Nanocomposites were analyzed by small-angle X-ray diffraction, transmission electron microscopy, and thermogravimetry. The clay dispersion depended on the structure of the alkylammonium used to make the clay more hydrophobic. E...

  • Poly(epsilon-caprolactone)/clay nanocomposites by in-Situ Intercalative Polymerization catalyzed by dibutyltin dimethoxide
    Macromolecules, 2002
    Co-Authors: Bénédicte Lepoittevin, Michael Alexandre, Nadège Pantoustier, Myriam Devalckenaere, Dana Kubies, Cédric Calberg, Robert Jérôme, Philippe Dubois
    Abstract:

    Poly(epsilon-caprolactone)/clay nanocomposites were prepared by in-Situ ring-opening Polymerization of epsilon-caprolactone by using dibutyltin dimethoxide as an initiator/catalyst. A nonmodified Na+-montmorillonite and two montmorillonites surface-modified by dimethyl 2-ethylhexyl (hydrogenated tallow alkyl) and methyl bis(2-hydroxyethyl) (hydrogenated tallow alkyl) ammonium cations, respectively, were used. The evolution of molecular weights was followed in relation to silicate surface modification and clay concentration. The alcohol-bearing organo-modified clay was a co-initiator for the Polymerization reaction and thus controlled the molecular weight of the PCL chains. Furthermore, the number-average molecular weight of the growing PCL chains linearly increased with the monomer conversion. Nanocomposites were analyzed by small-angle X-ray diffraction, transmission electron microscopy, and thermogravimetry. The clay dispersion depended on the structure of the alkylammonium used to make the clay more hydrophobic. Exfoliated nanocomposites were formed when hydroxyl-containing alkylammonium. was used; otherwise, intercalated structures were reported. Thermogravimetric analyses showed a higher degradation temperature for the exfoliated structures than for the intercalated ones, both of them exceeding the degradation temperature of unfilled poly(epsilon-caprolactone).Peer reviewe

Stephane Bruzaud - One of the best experts on this subject based on the ideXlab platform.

  • elaboration of poly e caprolactone g tinbo5 nanocomposites via in Situ metal complex initiated Intercalative Polymerization
    Macromolecular Materials and Engineering, 2004
    Co-Authors: Stephane Bruzaud, Jean-françois Carpentier, Yves Grohens
    Abstract:

    The preparation of poly(e-caprolactone)-g-TiNbO 5 nanocomposites via in Situ Intercalative Polymerization of e-caprolactone initiated by an aluminium complex is described. These nanocomposites were obtained in the presence of HTiNbO 5 mineral pre-treated by AlMe 3 , but non-modified by tetraalkylammonium cations. These hybrid materials obtained have been characterized by Fourier transform infrared absorption spectroscopy, wide-angle X-ray scattering, scanning electron microscopy, and dynamic mechanical analysis. Layered structure delamination and homogeneous distribution of mineral lamellae in the poly-(e-caprolactone)(PCL) is figured out and strong improvement of the mechanical properties achieved. The storage modulus of the nanocomposites is enhanced as compared to pure PCL and increases monotonously with the amount of the filler in the range 3 to 10 wt.-%.

  • Elaboration of Poly(ε‐caprolactone)‐g‐TiNbO5 Nanocomposites via in Situ Metal Complex Initiated Intercalative Polymerization
    Macromolecular Materials and Engineering, 2004
    Co-Authors: Stephane Bruzaud, Jean-françois Carpentier, Yves Grohens
    Abstract:

    The preparation of poly(e-caprolactone)-g-TiNbO 5 nanocomposites via in Situ Intercalative Polymerization of e-caprolactone initiated by an aluminium complex is described. These nanocomposites were obtained in the presence of HTiNbO 5 mineral pre-treated by AlMe 3 , but non-modified by tetraalkylammonium cations. These hybrid materials obtained have been characterized by Fourier transform infrared absorption spectroscopy, wide-angle X-ray scattering, scanning electron microscopy, and dynamic mechanical analysis. Layered structure delamination and homogeneous distribution of mineral lamellae in the poly-(e-caprolactone)(PCL) is figured out and strong improvement of the mechanical properties achieved. The storage modulus of the nanocomposites is enhanced as compared to pure PCL and increases monotonously with the amount of the filler in the range 3 to 10 wt.-%.

  • polysiloxane g tinbo5 nanocomposites synthesis via in Situ Intercalative Polymerization and preliminary characterization
    Chemistry of Materials, 2002
    Co-Authors: Stephane Bruzaud, Guy Levesque
    Abstract:

    New organic−inorganic hybrid materials, prepared via in Situ Intercalative Polymerization of cyclosiloxanes in the presence of (R4N)xH1-xTiNbO5, are described. The polysiloxane-g-TiNbO5 nanocomposites were identified mainly by Fourier transform infrared absorption spectroscopy, X-ray diffraction, transmission electron microscopy, and differential scanning calorimetry. All of these techniques confirm the proposed structure and show exfoliation of the initial mineral sheets in the polymer matrix is largely achieved. Elemental analysis indicates that grafting yields lie in the range 100−200% (w/w), corresponding to nanocomposites in which the mineral phase occupies between 50 and 25% of the total volume.

Yves Grohens - One of the best experts on this subject based on the ideXlab platform.

  • Elaboration of Poly(ε‐caprolactone)‐g‐TiNbO5 Nanocomposites via in Situ Metal Complex Initiated Intercalative Polymerization
    Macromolecular Materials and Engineering, 2004
    Co-Authors: Stephane Bruzaud, Jean-françois Carpentier, Yves Grohens
    Abstract:

    The preparation of poly(e-caprolactone)-g-TiNbO 5 nanocomposites via in Situ Intercalative Polymerization of e-caprolactone initiated by an aluminium complex is described. These nanocomposites were obtained in the presence of HTiNbO 5 mineral pre-treated by AlMe 3 , but non-modified by tetraalkylammonium cations. These hybrid materials obtained have been characterized by Fourier transform infrared absorption spectroscopy, wide-angle X-ray scattering, scanning electron microscopy, and dynamic mechanical analysis. Layered structure delamination and homogeneous distribution of mineral lamellae in the poly-(e-caprolactone)(PCL) is figured out and strong improvement of the mechanical properties achieved. The storage modulus of the nanocomposites is enhanced as compared to pure PCL and increases monotonously with the amount of the filler in the range 3 to 10 wt.-%.

  • elaboration of poly e caprolactone g tinbo5 nanocomposites via in Situ metal complex initiated Intercalative Polymerization
    Macromolecular Materials and Engineering, 2004
    Co-Authors: Stephane Bruzaud, Jean-françois Carpentier, Yves Grohens
    Abstract:

    The preparation of poly(e-caprolactone)-g-TiNbO 5 nanocomposites via in Situ Intercalative Polymerization of e-caprolactone initiated by an aluminium complex is described. These nanocomposites were obtained in the presence of HTiNbO 5 mineral pre-treated by AlMe 3 , but non-modified by tetraalkylammonium cations. These hybrid materials obtained have been characterized by Fourier transform infrared absorption spectroscopy, wide-angle X-ray scattering, scanning electron microscopy, and dynamic mechanical analysis. Layered structure delamination and homogeneous distribution of mineral lamellae in the poly-(e-caprolactone)(PCL) is figured out and strong improvement of the mechanical properties achieved. The storage modulus of the nanocomposites is enhanced as compared to pure PCL and increases monotonously with the amount of the filler in the range 3 to 10 wt.-%.

Yoon-bong Hahn - One of the best experts on this subject based on the ideXlab platform.

  • preparation of polystyrene montmorillonite nanocomposites using a new radical initiator montmorillonite hybrid via in Situ Intercalative Polymerization
    European Polymer Journal, 2004
    Co-Authors: Periyayya Uthirakumar, Kee Suk Nahm, Yoon-bong Hahn
    Abstract:

    Polystyrene/montmorillonite (PS/MMT) nanocomposites were prepared by in Situ free radical Intercalative Polymerization, using 1, 3 and 5 wt% of a new cationic radical initiator-MMT hybrid. The corresponding nanocomposites were designated as PS/MMT-1, PS/MMT-3 and PS/MMT-5, respectively. The silicate layers were well exfoliated and randomly dispersed in the PS/MMT-1 and PS/MMT-3, but were less exfoliated in the PS/MMT-5, due to the predominant extra-gallery Polymerization over the intra-gallery Polymerization. The unique properties of nanocomposites resulted from the strong interactions between the nano-sized silicate layer surfaces and the polymer chains. The onset temperature of thermal degradation, and the glass transition temperature, increased with increasing hybrid content, up to 3 wt%. The molecular weights of the PS in the PS/MMT-1 and PS/MMT-3 were less than those calculated theoretically, due to the predominant intra-gallery Polymerization.

  • Preparation of polystyrene/montmorillonite nanocomposites using a new radical initiator-montmorillonite hybrid via in Situ Intercalative Polymerization
    European Polymer Journal, 2004
    Co-Authors: Periyayya Uthirakumar, Kee Suk Nahm, Yoon-bong Hahn, Youn-sik Lee
    Abstract:

    Polystyrene/montmorillonite (PS/MMT) nanocomposites were prepared by in Situ free radical Intercalative Polymerization, using 1, 3 and 5 wt% of a new cationic radical initiator-MMT hybrid. The corresponding nanocomposites were designated as PS/MMT-1, PS/MMT-3 and PS/MMT-5, respectively. The silicate layers were well exfoliated and randomly dispersed in the PS/MMT-1 and PS/MMT-3, but were less exfoliated in the PS/MMT-5, due to the predominant extra-gallery Polymerization over the intra-gallery Polymerization. The unique properties of nanocomposites resulted from the strong interactions between the nano-sized silicate layer surfaces and the polymer chains. The onset temperature of thermal degradation, and the glass transition temperature, increased with increasing hybrid content, up to 3 wt%. The molecular weights of the PS in the PS/MMT-1 and PS/MMT-3 were less than those calculated theoretically, due to the predominant intra-gallery Polymerization.