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Young Moo Lee - One of the best experts on this subject based on the ideXlab platform.

  • novel preparative method for porous hydrogels using overrun process
    Polymer International, 2005
    Co-Authors: Hyungoo Kang, Sang Bong Lee, Young Moo Lee
    Abstract:

    Porous poly(vinyl alcohol) (PVA) hydrogels were prepared using the overrun process which is usually used in manufacturing ice cream. The Pores in the hydrogel formed exhibit dual-Pore Structure due to the injection of air bubbles and ice recrystallization. Morphological investigation revealed that overrun-processed hydrogels had Closed Pore Structures and that their Pore size and size distribution had been influenced by the impeller rate and concentration of polymer solution. The Closed-Pore Structure was reformed into interconnected open-Pore Structure at lower concentrations of the solution. The freeze–thawing process, which takes place in PVA cross-linking, has no effect on the bubble Structure, but removes the small Pores formed during ice recrystallization. Besides the swelling ratio of overrun-processed PVA hydrogels is increased tenfold in comparison with non-porous hydrogels. Overrun-processed hydrogels showed more rapid swelling kinetics than freeze-dried and film-like hydrogels due to their larger surface area. In the future, the overrun process can be applied to prepare porous scaffolds containing proteins, such as growth factors and other cytokines, without denaturation, because it operates at a low temperature. Copyright © 2004 Society of Chemical Industry

Paul A Kohl - One of the best experts on this subject based on the ideXlab platform.

  • low k porous methyl silsesquioxane and spin on glass
    Electrochemical and Solid State Letters, 1999
    Co-Authors: Abbe T Kohl, Richard Mimna, Robert A Shick, Larry F Rhodes, Zhong Lin Wang, Paul A Kohl
    Abstract:

    Low dielectric constant, porous silica was made from commercially available methyl silsesquioxane (MSQ) by the addition of a sacrificial polymer, substituted norbornene polymer containing triethoxysilyl groups (NB), to the MSQ. The silsesquioxane-NB polymer film mixture was thermally cured followed by decomposition of the NB at temperatures above 400°C. The dielectric constant of the MSQ was lowered from 2.7 to 2.3 by creating 70 nm Pores in the MSQ. The voids created in the MSQ exhibited a Closed-Pore Structure. The concentration of NB in the MSQ affected the number of Pores but not their size. Porous films were also created in a methyl siloxane spin-on-glass and its dielectric constant was lowered from 3.1 to 2.7. Infrared spectroscopy was used to follow the curing of the MSQ and decomposition of the NB. © 1999 The Electrochemical Society. S1099-0062(98)09-026-9. All rights reserved.

Hyungoo Kang - One of the best experts on this subject based on the ideXlab platform.

  • novel preparative method for porous hydrogels using overrun process
    Polymer International, 2005
    Co-Authors: Hyungoo Kang, Sang Bong Lee, Young Moo Lee
    Abstract:

    Porous poly(vinyl alcohol) (PVA) hydrogels were prepared using the overrun process which is usually used in manufacturing ice cream. The Pores in the hydrogel formed exhibit dual-Pore Structure due to the injection of air bubbles and ice recrystallization. Morphological investigation revealed that overrun-processed hydrogels had Closed Pore Structures and that their Pore size and size distribution had been influenced by the impeller rate and concentration of polymer solution. The Closed-Pore Structure was reformed into interconnected open-Pore Structure at lower concentrations of the solution. The freeze–thawing process, which takes place in PVA cross-linking, has no effect on the bubble Structure, but removes the small Pores formed during ice recrystallization. Besides the swelling ratio of overrun-processed PVA hydrogels is increased tenfold in comparison with non-porous hydrogels. Overrun-processed hydrogels showed more rapid swelling kinetics than freeze-dried and film-like hydrogels due to their larger surface area. In the future, the overrun process can be applied to prepare porous scaffolds containing proteins, such as growth factors and other cytokines, without denaturation, because it operates at a low temperature. Copyright © 2004 Society of Chemical Industry

Abbe T Kohl - One of the best experts on this subject based on the ideXlab platform.

  • low k porous methyl silsesquioxane and spin on glass
    Electrochemical and Solid State Letters, 1999
    Co-Authors: Abbe T Kohl, Richard Mimna, Robert A Shick, Larry F Rhodes, Zhong Lin Wang, Paul A Kohl
    Abstract:

    Low dielectric constant, porous silica was made from commercially available methyl silsesquioxane (MSQ) by the addition of a sacrificial polymer, substituted norbornene polymer containing triethoxysilyl groups (NB), to the MSQ. The silsesquioxane-NB polymer film mixture was thermally cured followed by decomposition of the NB at temperatures above 400°C. The dielectric constant of the MSQ was lowered from 2.7 to 2.3 by creating 70 nm Pores in the MSQ. The voids created in the MSQ exhibited a Closed-Pore Structure. The concentration of NB in the MSQ affected the number of Pores but not their size. Porous films were also created in a methyl siloxane spin-on-glass and its dielectric constant was lowered from 3.1 to 2.7. Infrared spectroscopy was used to follow the curing of the MSQ and decomposition of the NB. © 1999 The Electrochemical Society. S1099-0062(98)09-026-9. All rights reserved.

Sang Bong Lee - One of the best experts on this subject based on the ideXlab platform.

  • novel preparative method for porous hydrogels using overrun process
    Polymer International, 2005
    Co-Authors: Hyungoo Kang, Sang Bong Lee, Young Moo Lee
    Abstract:

    Porous poly(vinyl alcohol) (PVA) hydrogels were prepared using the overrun process which is usually used in manufacturing ice cream. The Pores in the hydrogel formed exhibit dual-Pore Structure due to the injection of air bubbles and ice recrystallization. Morphological investigation revealed that overrun-processed hydrogels had Closed Pore Structures and that their Pore size and size distribution had been influenced by the impeller rate and concentration of polymer solution. The Closed-Pore Structure was reformed into interconnected open-Pore Structure at lower concentrations of the solution. The freeze–thawing process, which takes place in PVA cross-linking, has no effect on the bubble Structure, but removes the small Pores formed during ice recrystallization. Besides the swelling ratio of overrun-processed PVA hydrogels is increased tenfold in comparison with non-porous hydrogels. Overrun-processed hydrogels showed more rapid swelling kinetics than freeze-dried and film-like hydrogels due to their larger surface area. In the future, the overrun process can be applied to prepare porous scaffolds containing proteins, such as growth factors and other cytokines, without denaturation, because it operates at a low temperature. Copyright © 2004 Society of Chemical Industry