The Experts below are selected from a list of 174 Experts worldwide ranked by ideXlab platform

Brigitte Voit - One of the best experts on this subject based on the ideXlab platform.

  • Synthesis of nanocomposites by in situ Metallocene-Catalyzed Polymerization of propene
    European Polymer Journal, 2015
    Co-Authors: S. Zakrzewska, A.c. Dos Ouros, N. Schramm, Dieter Jehnichen, Liane Häussler, Doris Pospiech, Brigitte Voit, Ulrich Schulze, Heloise O. Pastore
    Abstract:

    Abstract Organo-modified aluminophosphate with kanemite-like structure was used for the in situ synthesis of polypropylene (PP) nanocomposites performed by Metallocene-Catalyzed Polymerization. The filler exhibits a layered structure with different organic pending groups arranged in the interlayer space. Melt-compounded composites with the same filler were prepared for comparison. X-ray diffraction (XRD) and transmission electron microscopy (TEM) proved exfoliation of the filler in the PP matrix and formation of nanocomposite after in situ synthesis. In contrast, in the melt-composites the filler is agglomerated and only microcomposites are obtained.

  • Synthesis of Allyl-Terminated Polar Macromonomers by Metallocene-Catalyzed Polymerizations of 10-Undecene-1-ol
    ACS Macro Letters, 2012
    Co-Authors: Matthias Johannsen, Ulrich Schulze, Hartmut Komber, Karin Sahre, Brigitte Voit
    Abstract:

    Poly(10-undecene-1-ol) macromonomers were synthesized by Metallocene-Catalyzed Polymerization using vinyl chloride as a chain transfer agent. Using this technique, predominantly allyl terminated polymers could be obtained, which was verified by NMR spectroscopy and matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF-MS). By means of the mass spectra, a detailed interpretation of the nature of the head and end groups of these polymers was possible.

  • Synthesis of Allyl-Terminated Polar Macromonomers by Metallocene-Catalyzed Polymerizations of 10-Undecene-1-ol
    2012
    Co-Authors: Matthias Johannsen, Ulrich Schulze, Hartmut Komber, Karin Sahre, Brigitte Voit
    Abstract:

    Poly­(10-undecene-1-ol) macromonomers were synthesized by Metallocene-Catalyzed Polymerization using vinyl chloride as a chain transfer agent. Using this technique, predominantly allyl terminated polymers could be obtained, which was verified by NMR spectroscopy and matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF-MS). By means of the mass spectra, a detailed interpretation of the nature of the head and end groups of these polymers was possible

  • Thermal properties and crystalline structure of poly(10-undecene-1-ol)
    European Polymer Journal, 2011
    Co-Authors: Matthias Johannsen, Dieter Jehnichen, Liane Häussler, Ulrich Schulze, Brigitte Voit
    Abstract:

    Abstract Atactic and isotactic-rich poly(10-undecene-1-ol)s were synthesized by Metallocene-Catalyzed Polymerization. The thermal properties and the crystalline structure of the poly(10-undecene-1-ol)s were characterized using Dynamic Scanning Calorimetry (DSC), Temperature-Modulated DSC (MDSC), Fourier Transform Infrared Spectroscopy (FTIR), and Wide-Angle X-ray Scattering (WAXS). It was found that the polymers crystallize primarily at their side chains, which is indicated by similar arrangement of both isotactic-rich and atactic polymers. The polymers form smectic layer structures independent on their tacticity, however, for the isotactic-rich polymers, higher crystallinities were observed than for the atactic polymers in terms of higher melting enthalpies.

  • dsc and waxs investigations of polar macromonomers synthesized by Metallocene Catalyzed Polymerization
    2011
    Co-Authors: Matthias Johannsen, Dieter Jehnichen, Brigitte Voit, Ulrich Schulze, Polymerforschung Dresden
    Abstract:

    1the synthesis of poly(10-undecene-1-ol) using varied catalyst type, Polymerization temperature and monomer concentration as well as the characterization of the chemical structure was described. Here, in continuation, we report on the thermal properties and the crystalline structure of poly(10-undecene-1-ol) as an interesting new macromonomer. Experimental Materials, Polymerization conditions and the characterization of the chemical structure of poly(10-undecene-1-ol) were described recently in detail. 1 Poly(1-undecene)s were synthesized in the similar manner as described for the poly(10-undecene-1-ol)s. The poly(1-undecene)s are precipitated in an acidified mixture of 1L ethanol and 1L water and after separation the organic phase was washed with ethanol before drying at 55 °C under vacuum. Instrumentation. The Differential Scanning Calorimetry (DSC) data were acquired using a TA Instruments DSC Q 1000 calorimeter. Samples were subjected to a cycle of first heating, cooling and second heating with a scan

Ulrich Schulze - One of the best experts on this subject based on the ideXlab platform.

  • Synthesis of nanocomposites by in situ Metallocene-Catalyzed Polymerization of propene
    European Polymer Journal, 2015
    Co-Authors: S. Zakrzewska, A.c. Dos Ouros, N. Schramm, Dieter Jehnichen, Liane Häussler, Doris Pospiech, Brigitte Voit, Ulrich Schulze, Heloise O. Pastore
    Abstract:

    Abstract Organo-modified aluminophosphate with kanemite-like structure was used for the in situ synthesis of polypropylene (PP) nanocomposites performed by Metallocene-Catalyzed Polymerization. The filler exhibits a layered structure with different organic pending groups arranged in the interlayer space. Melt-compounded composites with the same filler were prepared for comparison. X-ray diffraction (XRD) and transmission electron microscopy (TEM) proved exfoliation of the filler in the PP matrix and formation of nanocomposite after in situ synthesis. In contrast, in the melt-composites the filler is agglomerated and only microcomposites are obtained.

  • Synthesis of Allyl-Terminated Polar Macromonomers by Metallocene-Catalyzed Polymerizations of 10-Undecene-1-ol
    ACS Macro Letters, 2012
    Co-Authors: Matthias Johannsen, Ulrich Schulze, Hartmut Komber, Karin Sahre, Brigitte Voit
    Abstract:

    Poly(10-undecene-1-ol) macromonomers were synthesized by Metallocene-Catalyzed Polymerization using vinyl chloride as a chain transfer agent. Using this technique, predominantly allyl terminated polymers could be obtained, which was verified by NMR spectroscopy and matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF-MS). By means of the mass spectra, a detailed interpretation of the nature of the head and end groups of these polymers was possible.

  • Synthesis of Allyl-Terminated Polar Macromonomers by Metallocene-Catalyzed Polymerizations of 10-Undecene-1-ol
    2012
    Co-Authors: Matthias Johannsen, Ulrich Schulze, Hartmut Komber, Karin Sahre, Brigitte Voit
    Abstract:

    Poly­(10-undecene-1-ol) macromonomers were synthesized by Metallocene-Catalyzed Polymerization using vinyl chloride as a chain transfer agent. Using this technique, predominantly allyl terminated polymers could be obtained, which was verified by NMR spectroscopy and matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF-MS). By means of the mass spectra, a detailed interpretation of the nature of the head and end groups of these polymers was possible

  • Thermal properties and crystalline structure of poly(10-undecene-1-ol)
    European Polymer Journal, 2011
    Co-Authors: Matthias Johannsen, Dieter Jehnichen, Liane Häussler, Ulrich Schulze, Brigitte Voit
    Abstract:

    Abstract Atactic and isotactic-rich poly(10-undecene-1-ol)s were synthesized by Metallocene-Catalyzed Polymerization. The thermal properties and the crystalline structure of the poly(10-undecene-1-ol)s were characterized using Dynamic Scanning Calorimetry (DSC), Temperature-Modulated DSC (MDSC), Fourier Transform Infrared Spectroscopy (FTIR), and Wide-Angle X-ray Scattering (WAXS). It was found that the polymers crystallize primarily at their side chains, which is indicated by similar arrangement of both isotactic-rich and atactic polymers. The polymers form smectic layer structures independent on their tacticity, however, for the isotactic-rich polymers, higher crystallinities were observed than for the atactic polymers in terms of higher melting enthalpies.

  • dsc and waxs investigations of polar macromonomers synthesized by Metallocene Catalyzed Polymerization
    2011
    Co-Authors: Matthias Johannsen, Dieter Jehnichen, Brigitte Voit, Ulrich Schulze, Polymerforschung Dresden
    Abstract:

    1the synthesis of poly(10-undecene-1-ol) using varied catalyst type, Polymerization temperature and monomer concentration as well as the characterization of the chemical structure was described. Here, in continuation, we report on the thermal properties and the crystalline structure of poly(10-undecene-1-ol) as an interesting new macromonomer. Experimental Materials, Polymerization conditions and the characterization of the chemical structure of poly(10-undecene-1-ol) were described recently in detail. 1 Poly(1-undecene)s were synthesized in the similar manner as described for the poly(10-undecene-1-ol)s. The poly(1-undecene)s are precipitated in an acidified mixture of 1L ethanol and 1L water and after separation the organic phase was washed with ethanol before drying at 55 °C under vacuum. Instrumentation. The Differential Scanning Calorimetry (DSC) data were acquired using a TA Instruments DSC Q 1000 calorimeter. Samples were subjected to a cycle of first heating, cooling and second heating with a scan

Matthias Johannsen - One of the best experts on this subject based on the ideXlab platform.

  • Synthesis of Allyl-Terminated Polar Macromonomers by Metallocene-Catalyzed Polymerizations of 10-Undecene-1-ol
    ACS Macro Letters, 2012
    Co-Authors: Matthias Johannsen, Ulrich Schulze, Hartmut Komber, Karin Sahre, Brigitte Voit
    Abstract:

    Poly(10-undecene-1-ol) macromonomers were synthesized by Metallocene-Catalyzed Polymerization using vinyl chloride as a chain transfer agent. Using this technique, predominantly allyl terminated polymers could be obtained, which was verified by NMR spectroscopy and matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF-MS). By means of the mass spectra, a detailed interpretation of the nature of the head and end groups of these polymers was possible.

  • Synthesis of Allyl-Terminated Polar Macromonomers by Metallocene-Catalyzed Polymerizations of 10-Undecene-1-ol
    2012
    Co-Authors: Matthias Johannsen, Ulrich Schulze, Hartmut Komber, Karin Sahre, Brigitte Voit
    Abstract:

    Poly­(10-undecene-1-ol) macromonomers were synthesized by Metallocene-Catalyzed Polymerization using vinyl chloride as a chain transfer agent. Using this technique, predominantly allyl terminated polymers could be obtained, which was verified by NMR spectroscopy and matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF-MS). By means of the mass spectra, a detailed interpretation of the nature of the head and end groups of these polymers was possible

  • Thermal properties and crystalline structure of poly(10-undecene-1-ol)
    European Polymer Journal, 2011
    Co-Authors: Matthias Johannsen, Dieter Jehnichen, Liane Häussler, Ulrich Schulze, Brigitte Voit
    Abstract:

    Abstract Atactic and isotactic-rich poly(10-undecene-1-ol)s were synthesized by Metallocene-Catalyzed Polymerization. The thermal properties and the crystalline structure of the poly(10-undecene-1-ol)s were characterized using Dynamic Scanning Calorimetry (DSC), Temperature-Modulated DSC (MDSC), Fourier Transform Infrared Spectroscopy (FTIR), and Wide-Angle X-ray Scattering (WAXS). It was found that the polymers crystallize primarily at their side chains, which is indicated by similar arrangement of both isotactic-rich and atactic polymers. The polymers form smectic layer structures independent on their tacticity, however, for the isotactic-rich polymers, higher crystallinities were observed than for the atactic polymers in terms of higher melting enthalpies.

  • dsc and waxs investigations of polar macromonomers synthesized by Metallocene Catalyzed Polymerization
    2011
    Co-Authors: Matthias Johannsen, Dieter Jehnichen, Brigitte Voit, Ulrich Schulze, Polymerforschung Dresden
    Abstract:

    1the synthesis of poly(10-undecene-1-ol) using varied catalyst type, Polymerization temperature and monomer concentration as well as the characterization of the chemical structure was described. Here, in continuation, we report on the thermal properties and the crystalline structure of poly(10-undecene-1-ol) as an interesting new macromonomer. Experimental Materials, Polymerization conditions and the characterization of the chemical structure of poly(10-undecene-1-ol) were described recently in detail. 1 Poly(1-undecene)s were synthesized in the similar manner as described for the poly(10-undecene-1-ol)s. The poly(1-undecene)s are precipitated in an acidified mixture of 1L ethanol and 1L water and after separation the organic phase was washed with ethanol before drying at 55 °C under vacuum. Instrumentation. The Differential Scanning Calorimetry (DSC) data were acquired using a TA Instruments DSC Q 1000 calorimeter. Samples were subjected to a cycle of first heating, cooling and second heating with a scan

  • Poly(10-undecene-1-ol) characterized by MALDI-TOF MS and NMR spectroscopy
    European Polymer Journal, 2011
    Co-Authors: Ulrich Schulze, Matthias Johannsen, Hartmut Komber, Karin Sahre, Brigitte Voit
    Abstract:

    Abstract Poly(10-undecene-1-ol)s were synthesized by Metallocene-Catalyzed Polymerization. MALDI-TOF MS allows obtaining detailed information on the monomer units in the polymer chains and the nature of the head and end groups of these polymers in dependence on the Al alkyl triisobutyl aluminum (TIBA) as well as methylalumoxan (MAO), both used as protecting agent for the hydroxyl groups of the monomer. The peak-to-peak distances of the main peaks could be distinctly assigned to the monomer unit 10-undecene-1-ol. Evaluating the MALDI-TOF peak distributions, polymers with -H, -C4H9, -CH3 head groups in combination with vinylidene and saturated (–CH3) end groups could be detected. By 1H NMR spectroscopy, it was verified that with the used catalysts polymers with vinylidene end groups were obtained predominantly. The presence of saturated end groups could be proved qualitatively by combination of 1H and 13C NMR spectroscopy for polymers produced by TIBA protection, which strikingly confirm the results from MALDI-TOF MS. For the polymers prepared with only MAO protection, saturated groups are also proved but discrimination between head and end groups was not possible. A Polymerization mechanism corresponding to the detected different head and end groups is proposed.

Klaus Müllen - One of the best experts on this subject based on the ideXlab platform.

  • Anisotropic Supports in Metallocene‐Catalyzed Polymerizations: Templates to Obtain Polyolefin Fibers
    Macromolecular Materials and Engineering, 2014
    Co-Authors: Florian E. Golling, Markus Klapper, Kathrin Friedemann, Daniel Crespy, Klaus Müllen
    Abstract:

    The formation of polyethylene fibers via Metallocene-Catalyzed Polymerization using anisotropic organic supports as templates is presented. The supports are obtained by electrospinning a mixture of polyvinyl alcohol and functionalized polystyrene nanoparticles. After loading the MAO-activated Metallocene on the support and olefin Polymerization, the obtained catalyst system yields polyethylene fibers displaying a core-sheath structure with a controlled diameter in the range of 0.3–2 μm. This strategy represents a direct method to fabricate well-defined polyolefin fibers and mats during the Polymerization without any further processing.

  • Metallocene‐Catalyzed Polymerization in Nonaqueous Fluorous Emulsion
    Macromolecular Chemistry and Physics, 2007
    Co-Authors: Svetlin Nenov, Christopher G. Clark, Markus Klapper, Klaus Müllen
    Abstract:

    A nonaqueous organic-in-fluorous emulsion applicable for Polymerization using water-sensitive catalysts is presented. With statistical biphasic copolymers based on poly(4-hydroxystyrene) containing fluorinated and nonfluorinated alkyl side chains, emulsions of hydrocarbons dispersed in perfluorocarbons were stabilized. The addition of Metallocenes, activated by methylalumoxane (MAO), enabled the Polymerization of olefins inside this highly hydrophobic system. High molecular weight polyolefin nanoparticles (M n up to 450 000) of polyethylene and poly(propylene) were synthesized without supporting the catalyst and without reactor fouling. In this diffusion-controlled process, the sizes of the particles were controlled by the reaction time and the ratio of the emulsifier to solvents.

  • Metallocene Catalyzed Polymerization in nonaqueous fluorous emulsion
    Macromolecular Chemistry and Physics, 2007
    Co-Authors: Svetlin Nenov, Christopher G. Clark, Markus Klapper, Klaus Müllen
    Abstract:

    A nonaqueous organic-in-fluorous emulsion applicable for Polymerization using water-sensitive catalysts is presented. With statistical biphasic copolymers based on poly(4-hydroxystyrene) containing fluorinated and nonfluorinated alkyl side chains, emulsions of hydrocarbons dispersed in perfluorocarbons were stabilized. The addition of Metallocenes, activated by methylalumoxane (MAO), enabled the Polymerization of olefins inside this highly hydrophobic system. High molecular weight polyolefin nanoparticles (M n up to 450 000) of polyethylene and poly(propylene) were synthesized without supporting the catalyst and without reactor fouling. In this diffusion-controlled process, the sizes of the particles were controlled by the reaction time and the ratio of the emulsifier to solvents.

Hartmut Komber - One of the best experts on this subject based on the ideXlab platform.

  • Synthesis of Allyl-Terminated Polar Macromonomers by Metallocene-Catalyzed Polymerizations of 10-Undecene-1-ol
    ACS Macro Letters, 2012
    Co-Authors: Matthias Johannsen, Ulrich Schulze, Hartmut Komber, Karin Sahre, Brigitte Voit
    Abstract:

    Poly(10-undecene-1-ol) macromonomers were synthesized by Metallocene-Catalyzed Polymerization using vinyl chloride as a chain transfer agent. Using this technique, predominantly allyl terminated polymers could be obtained, which was verified by NMR spectroscopy and matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF-MS). By means of the mass spectra, a detailed interpretation of the nature of the head and end groups of these polymers was possible.

  • Synthesis of Allyl-Terminated Polar Macromonomers by Metallocene-Catalyzed Polymerizations of 10-Undecene-1-ol
    2012
    Co-Authors: Matthias Johannsen, Ulrich Schulze, Hartmut Komber, Karin Sahre, Brigitte Voit
    Abstract:

    Poly­(10-undecene-1-ol) macromonomers were synthesized by Metallocene-Catalyzed Polymerization using vinyl chloride as a chain transfer agent. Using this technique, predominantly allyl terminated polymers could be obtained, which was verified by NMR spectroscopy and matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF-MS). By means of the mass spectra, a detailed interpretation of the nature of the head and end groups of these polymers was possible

  • Poly(10-undecene-1-ol) characterized by MALDI-TOF MS and NMR spectroscopy
    European Polymer Journal, 2011
    Co-Authors: Ulrich Schulze, Matthias Johannsen, Hartmut Komber, Karin Sahre, Brigitte Voit
    Abstract:

    Abstract Poly(10-undecene-1-ol)s were synthesized by Metallocene-Catalyzed Polymerization. MALDI-TOF MS allows obtaining detailed information on the monomer units in the polymer chains and the nature of the head and end groups of these polymers in dependence on the Al alkyl triisobutyl aluminum (TIBA) as well as methylalumoxan (MAO), both used as protecting agent for the hydroxyl groups of the monomer. The peak-to-peak distances of the main peaks could be distinctly assigned to the monomer unit 10-undecene-1-ol. Evaluating the MALDI-TOF peak distributions, polymers with -H, -C4H9, -CH3 head groups in combination with vinylidene and saturated (–CH3) end groups could be detected. By 1H NMR spectroscopy, it was verified that with the used catalysts polymers with vinylidene end groups were obtained predominantly. The presence of saturated end groups could be proved qualitatively by combination of 1H and 13C NMR spectroscopy for polymers produced by TIBA protection, which strikingly confirm the results from MALDI-TOF MS. For the polymers prepared with only MAO protection, saturated groups are also proved but discrimination between head and end groups was not possible. A Polymerization mechanism corresponding to the detected different head and end groups is proposed.

  • Synthesis of poly(10-undecene-1-ol) by Metallocene-Catalyzed Polymerization
    European Polymer Journal, 2010
    Co-Authors: Ulrich Schulze, Matthias Johannsen, Robert Haschick, Hartmut Komber, Albena Lederer, Brigitte Voit
    Abstract:

    Abstract Poly(10-undecene-1-ol)s as precursors for potential polar macromonomers were synthesized by Metallocene-Catalyzed Polymerization. For the use as macromonomers, polymerizable terminal double bonds are an important requirement and thus, the investigation of the end groups in the polymers was the main focus of this study. The influence of the catalyst and Polymerization conditions on the chain length of the polymer backbone, the monomer conversion as well as the end group characteristics were analyzed. It was possible to find conditions for preparing poly(10-undecene-1-ol)s with terminal double bonds using the catalyst system Cp2ZrCl2/MAO. Two other chosen catalysts produced mainly internal double bonds. The poly(10-undecene-1-ol)s could be prepared as atactic or isotactic-rich materials depending on the catalyst used.