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Aluminosilicates

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Ulrich Wiesner – 1st expert on this subject based on the ideXlab platform

  • Hexagonally Patterned Lamellar Morphology in ABC Triblock Copolymer/Aluminosilicate Nanocomposites
    Chemistry of Materials, 2008
    Co-Authors: Gilman E S Toombes, Surbhi Mahajan, Malcolm Thomas, Phong Du, Mark W Tate, Sol M Gruner, Ulrich Wiesner

    Abstract:

    X-ray scattering and electron microscopy were used to characterize the structure of poly(ethylene-alt-propylene-block-ethylene oxide-block-n-hexyl methacrylate) (PEP-b-PEO-b-PHMA) triblock copolymer/aluminosilicate hybrid materials in which the volume fraction of the PEP end-block (0.09 ≤ fPEP ≤ 0.12) was much smaller than that of the PEO-aluminosilicate (0.28 ≤ fPEO+aluminosilicate ≤ 0.44) and PHMA (0.47 ≤ fPHMA ≤ 0.60) domains. These hybrid compounds formed a hexagonally patterned lamellar morphology in which the lamellae were aligned parallel to the material surface (lamellar repeat spacing = 33.0 ± 3.3 nm, in-plane row spacing = 21.7 ± 1.9 nm). Both the PHMA and PEO-aluminosilicate phases formed continuous, two-dimensional domains permitting individual sheets of the material to be isolated by dispersal in organic solvent. Within each sheet, the lamellar PEO-aluminosilicate domain was hexagonally patterned by an array of “holes” with lower aluminosilicate density. Since the enthalpy of mixing for the s…

  • hexagonally patterned lamellar morphology in abc triblock copolymer aluminosilicate nanocomposites
    Chemistry of Materials, 2008
    Co-Authors: Gilman E S Toombes, Surbhi Mahajan, Malcolm Thomas, Phong Du, Mark W Tate, Sol M Gruner, Ulrich Wiesner

    Abstract:

    X-ray scattering and electron microscopy were used to characterize the structure of poly(ethylene-alt-propylene-block-ethylene oxide-block-n-hexyl methacrylate) (PEP-b-PEO-b-PHMA) triblock copolymer/aluminosilicate hybrid materials in which the volume fraction of the PEP end-block (0.09 ≤ fPEP ≤ 0.12) was much smaller than that of the PEO-aluminosilicate (0.28 ≤ fPEO+aluminosilicate ≤ 0.44) and PHMA (0.47 ≤ fPHMA ≤ 0.60) domains. These hybrid compounds formed a hexagonally patterned lamellar morphology in which the lamellae were aligned parallel to the material surface (lamellar repeat spacing = 33.0 ± 3.3 nm, in-plane row spacing = 21.7 ± 1.9 nm). Both the PHMA and PEO-aluminosilicate phases formed continuous, two-dimensional domains permitting individual sheets of the material to be isolated by dispersal in organic solvent. Within each sheet, the lamellar PEO-aluminosilicate domain was hexagonally patterned by an array of “holes” with lower aluminosilicate density. Since the enthalpy of mixing for the s…

  • the plumber s nightmare a new morphology in block copolymer ceramic nanocomposites and mesoporous Aluminosilicates
    Journal of the American Chemical Society, 2003
    Co-Authors: Adam C Finnefrock, Gilman E S Toombes, Sol M Gruner, Ralph Ulrich, Ulrich Wiesner

    Abstract:

    A novel cubic bicontinuous morphology is found in polymer−ceramic nanocomposites and mesoporous Aluminosilicates that are derived by an amphiphilic diblock copolymer, poly(isoprene-b-ethylene oxide) (PI-b-PEO), used as a structure-directing agent for an inorganic aluminosilicate. Small-angle X-ray scattering (SAXS) was employed to unambiguously identify the Im3m crystallographic symmetry of the materials by fitting individual Bragg peak positions in the two-dimensional X-ray images. Structure factor calculations, in conjunction with results from transmission electron microscopy, were used to narrow the range of possible structures consistent with the symmetry and showed the plumber’s nightmare morphology to be consistent with the data. The samples are made by deposition onto a substrate that imposes a strain field, generating a lattice distortion. This distortion is quantitatively analyzed and shown to have resulted in shrinkage of the crystallites by approximately one-third in a direction perpendicular …

Fengshou Xiao – 2nd expert on this subject based on the ideXlab platform

  • hydrothermally stable ordered hexagonal mesoporous Aluminosilicates assembled from a triblock copolymer and preformed aluminosilicate precursors in strongly acidic media
    Chemistry of Materials, 2002
    Co-Authors: Shuo Wu, Fengshou Xiao, Dongsheng Li, Xiaozong Zhang

    Abstract:

    Mesoporous Aluminosilicates (MAS-9) with ordered hexagonal struture have been prepared by assembly of preformed aluminosilicate precursors with a triblock copolymer in strongly acidic media by a two-step procedure. MAS-9 exhibits extraordinarily good hydrothermal stability and high catalytic activities for the cracking of both cumene and 1,3,5-tri-isopropylbenzene. Even after treatment in boiling water for 120 h, MAS-9 continues to show a large surface area (680 m2/g) and high catalytic activities. Furthermore, this two-step strategy could be used as a new general method for the preparation of mesoporous aluminosilicate materials under strongly acidic conditions.

  • mesoporous Aluminosilicates with ordered hexagonal structure strong acidity and extraordinary hydrothermal stability at high temperatures
    Journal of the American Chemical Society, 2001
    Co-Authors: Zongtao Zhang, Fengshou Xiao, Runwei Wang, Yi Yu, Ze Zhang, Yiqian Wang, Dongyuan Zhao

    Abstract:

    Highly ordered hexagonal mesoporous Aluminosilicates (MAS-5) with uniform pore sizes have been successfully synthesized from assembly of preformed aluminosilcate precursors with cetyltrimethylammonium bromide (CTAB) surfactant. The aluminosilicate precursors were obtained by heating, at 100−140 °C for 2−10 h, aluminasilica gels at the Al2O3/SiO2/TEAOH/H2O molar ratios of 1.0/7.0−350/10.0−33.0/500−2000. Mesoporous MAS-5 shows extraordinary stability both in boiling water (over 300 h) and in steam (800 °C for 2 h). Temperature-programmed desorption of ammonia shows that the acidic strength of MAS-5 is much higher than that of MCM-41 and is comparable to that of microporous Beta zeolite. In catalytic cracking of 1,3,5-triisopropylbenzene and alkylation of isobutane with butene, MAS-5 exhibits greater catalytic activity and selectivity, as compared with MCM-41 and HZSM-5. The MAS-5 samples were characterized with infrared, UV−Raman, and NMR spectroscopy and numerous other techniques. The results suggest that …

  • strongly acidic and high temperature hydrothermally stable mesoporous Aluminosilicates with ordered hexagonal structure
    Angewandte Chemie, 2001
    Co-Authors: Zongtao Zhang, Runwei Wang, Yi Yu, Dongyuan Zhao, Fengshou Xiao

    Abstract:

    Publisher Summary This chapter discusses strong acidic and high-temperature hydrothermally stable mesoporous Aluminosilicates with well-ordered hexagonal structure. These mesoporous Aluminosilicates have been successfully synthesized from the assembly of preformed aluminosilicate precursors with cetyltrimethylammonium bromide (CTAB) surfactant. The MAS-5 shows extraordinary stability both in boiling water and in steam. Temperature-programmed desorption of ammonia (NH 3 ) shows that the acidic strength of MAS-5 is much higher than that of MCM-41.

Dongyuan Zhao – 3rd expert on this subject based on the ideXlab platform

  • mesoporous Aluminosilicates with ordered hexagonal structure strong acidity and extraordinary hydrothermal stability at high temperatures
    Journal of the American Chemical Society, 2001
    Co-Authors: Zongtao Zhang, Fengshou Xiao, Runwei Wang, Yi Yu, Ze Zhang, Yiqian Wang, Dongyuan Zhao

    Abstract:

    Highly ordered hexagonal mesoporous Aluminosilicates (MAS-5) with uniform pore sizes have been successfully synthesized from assembly of preformed aluminosilcate precursors with cetyltrimethylammonium bromide (CTAB) surfactant. The aluminosilicate precursors were obtained by heating, at 100−140 °C for 2−10 h, aluminasilica gels at the Al2O3/SiO2/TEAOH/H2O molar ratios of 1.0/7.0−350/10.0−33.0/500−2000. Mesoporous MAS-5 shows extraordinary stability both in boiling water (over 300 h) and in steam (800 °C for 2 h). Temperature-programmed desorption of ammonia shows that the acidic strength of MAS-5 is much higher than that of MCM-41 and is comparable to that of microporous Beta zeolite. In catalytic cracking of 1,3,5-triisopropylbenzene and alkylation of isobutane with butene, MAS-5 exhibits greater catalytic activity and selectivity, as compared with MCM-41 and HZSM-5. The MAS-5 samples were characterized with infrared, UV−Raman, and NMR spectroscopy and numerous other techniques. The results suggest that …

  • strongly acidic and high temperature hydrothermally stable mesoporous Aluminosilicates with ordered hexagonal structure
    Angewandte Chemie, 2001
    Co-Authors: Zongtao Zhang, Runwei Wang, Yi Yu, Dongyuan Zhao, Fengshou Xiao

    Abstract:

    Publisher Summary This chapter discusses strong acidic and high-temperature hydrothermally stable mesoporous Aluminosilicates with well-ordered hexagonal structure. These mesoporous Aluminosilicates have been successfully synthesized from the assembly of preformed aluminosilicate precursors with cetyltrimethylammonium bromide (CTAB) surfactant. The MAS-5 shows extraordinary stability both in boiling water and in steam. Temperature-programmed desorption of ammonia (NH 3 ) shows that the acidic strength of MAS-5 is much higher than that of MCM-41.