The Experts below are selected from a list of 309 Experts worldwide ranked by ideXlab platform

William J. Koros - One of the best experts on this subject based on the ideXlab platform.

  • challenges in forming successful mixed Matrix membranes with rigid polymeric Materials
    Journal of Applied Polymer Science, 2002
    Co-Authors: Rajiv Mahajan, Michael Schaeffer, Ryan L Burns, William J. Koros
    Abstract:

    Mixed Matrix Materials comprised of molecular sieve domains embedded in processable polymer matrices have the potential to provide membranes with higher permselectivity and equivalent productivity compared to existing membrane Materials. It has been shown that successful mixed Matrix Materials can be formed using relatively low glass transition (Tg) polymers that have a favorable interaction with the sieves. This article extends this earlier work to include the use of more practical rigid Matrix polymers with high Tgs that can ultimately be used in forming high-performance mixed Matrix layers for composite membranes. Initial attempts to form mixed Matrix Materials based on high Tg polymers with a type 4A zeolite resulted in poor adhesion between the polymer and sieve. Correcting this problem was pursued in this study by forming the composite material close to the Tg of the polymer by addition of a plasticizer to match the Matrix Tg with the solvent volatility. Forming the films at elevated temperatures presented substantial challenges, and this work discusses overcoming these challenges in detail. With some modifications in the film casting procedure, successful Materials were achieved. Promising oxygen/nitrogen transport results are presented for these zeolite 4A–Matrimid®/plasticizer membranes, and this data compares favorably with predictions of the well-known Maxwell model for composite systems. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 881–890, 2002

  • mixed Matrix membrane Materials with glassy polymers part 2
    Polymer Engineering and Science, 2002
    Co-Authors: Rajiv Mahajan, William J. Koros
    Abstract:

    Analysis presented in Part 1 of this paper indicated the importance of optimization of the transport properties of the interfacial region to achieve ideal mixed Matrix Materials. This insight is used in this paper to guide mixed Matrix material formation with more conventional gas separation polymers. Conventional gas separation Materials are rigid, and, as seen earlier, lead to the formation of an undesirable interphase under conventional casting techniques. We show in this study that if flexibility can be maintained during membrane formation with a polymer that interacts favorably with the sieve, successful mixed Matrix Materials result, even with rigid polymeric Materials. Flexibility during membrane formation can be achieved by formation of films at temperatures close to the glass transition temperature of the polymer. Moreover, combination of chemical coupling and flexibility during membrane formation produces even more significant improvements in membrane performance. This approach leads to the formation of mixed Matrix material with transport properties exceeding the upper bound currently achieved by conventional membrane Materials. Another approach to form successful mixed Matrix Materials involves tailoring the interface by use of integral chemical linkages that are intrinsically part of the chain backbone. Such linkages appear to tighten the interface sufficiently to prevent “nonselective leakage” along the interface. This approach is demonstrated by directly bonding a reactive polymer onto the sieve surface under proper processing conditions.

  • mixed Matrix membrane Materials with glassy polymers part 1
    Polymer Engineering and Science, 2002
    Co-Authors: Rajiv Mahajan, William J. Koros
    Abstract:

    Mixed Matrix Materials comprising molecular sieve entities embedded in a polymer Matrix can economically increase membrane permselectivity, thereby addressing a key challenge hindering the widespread use of membrane-based gas separations. Prior work has clarified the importance of proper selection of the dispersed sieve phase and the continuous Matrix phase based on their intrinsic transport properties. Proper material selection for the two components, while necessary, is not sufficient since the interfacial contact zone appears to be equally important to achieve optimum transport properties. Specifically, it was found that chemical coupling of the sieve to the polymer can lead to better macroscopic adhesion but to even poorer transport properties than in the absence of the adhesion promoter. This counterintuitive behavior may be attributed to a nanometric region of disturbed packing at the polymer sieve interphase. The poor properties are believed to result from “leakage” of gas molecules along this nanometric interface. The Maxwell model was modified to take into account these complexities and to provide a first order quantification of the nanometric interphase. The analysis indicates that optimization of the transport properties of the interfacial region is key to the formation of ideal mixed Matrix Materials. This approach is used in the second part of this paper to form successful mixed Matrix membrane Materials.

  • Challenges in forming successful mixed Matrix membranes with rigid polymeric Materials
    Journal of Applied Polymer Science, 2002
    Co-Authors: Rajiv Mahajan, Ryan Burns, Michael Schaeffer, William J. Koros
    Abstract:

    Mixed Matrix Materials comprised of molecular sieve domains embedded in processable polymer matrices have the potential to provide membranes with higher permselectivity and equivalent productivity compared to existing membrane Materials. It has been shown that successful mixed Matrix Materials can be formed using relatively low glass transition (T-g) polymers that have a favorable interaction with the sieves. This article extends this earlier work to include the use of more practical rigid Matrix polymers with high T(g)s that can ultimately be used in forming high-performance mixed Matrix layers for composite membranes. Initial attempts to form mixed Matrix Materials based on high T-g polymers with a type 4A zeolite resulted in poor adhesion between the polymer and sieve. Correcting composite material close to the T-g of the polymer by addition of a plasticizer to match the Matrix T-g with the solvent volatility. Forming the films at elevated temperatures presented substantial challenges, and this work discusses overcoming these challenges in detail. With some modifications in the film casting procedure, successful Materials were achieved. Promising oxygen/nitrogen transport results are presented for these zeolite 4A-Matrimid(R)/plasticizer membranes, and this data compares favorably with predictions of the well-known Maxwell model for composite systems. (C) 2002 Wiley Periodicals, Inc.

Wolfgang Kern - One of the best experts on this subject based on the ideXlab platform.

  • Epoxy silicone based Matrix Materials for two-photon patterning of optical waveguides
    Polymer, 2011
    Co-Authors: Rachel Woods, Sonja Feldbacher, Valentin Satzinger, G. Langer, Volker Schmidt, Wolfgang Kern
    Abstract:

    Abstract 3D polymeric optical waveguides play an intrinsic role in a rapidly developing area of broadband communications. Advances in the field of electronics means there is a greater demand for higher speeds, larger data storage, smaller components and the improvement in the design of integrated optical circuits. Two-photon photopolymerisation (2PP) is a promising three-dimensional microfabrication technique, which can be used to produce structures in the sub-micron region. With the use of near-infrared (NIR) lasers, 3D optical waveguides can be fabricated in polymer-based Matrix Materials, based on the increase of the refractive index in the vicinity of the laser focus. The development of a new polysiloxane material, used in the study of the integration of optical interconnects on printed circuit boards is presented. The desirable properties of epoxy functional silicones crosslinked with diamines deem them suitable for such applications. An epoxy terminated polysiloxane; crosslinked with an aminopropyl disiloxane has been developed as a suitable material for the fabrication of optical waveguides by two-photon absorption (TPA). The material fulfils a number of requirements including a good refractive index contrast between the Matrix material and inscribed waveguide, full flexibility and high thermal stability. The Matrix material was characterised by Fourier transform infrared spectroscopy (FTIR) and thermal gravimetric analysis (TGA) The optical waveguides were characterised by phase contrast microscopy, and were directly integrated onto specially designed PCB’s by correctly positioning waveguide bundles between optoelectronic components using TPA, making it possible to detect transmitted photocurrents.

  • Epoxy silicone based Matrix Materials for two-photon patterning of optical waveguides
    Polymer, 2011
    Co-Authors: Rachel Woods, Sonja Feldbacher, Valentin Satzinger, G. Langer, Volker Schmidt, Wolfgang Kern
    Abstract:

    3D polymeric optical waveguides play an intrinsic role in a rapidly developing area of broadband communications. Advances in the field of electronics means there is a greater demand for higher speeds, larger data storage, smaller components and the improvement in the design of integrated optical circuits. Two-photon photopolymerisation (2PP) is a promising three-dimensional microfabrication technique, which can be used to produce structures in the sub-micron region. With the use of near-infrared (NIR) lasers, 3D optical waveguides can be fabricated in polymer-based Matrix Materials, based on the increase of the refractive index in the vicinity of the laser focus. The development of a new polysiloxane material, used in the study of the integration of optical interconnects on printed circuit boards is presented. The desirable properties of epoxy functional silicones crosslinked with diamines deem them suitable for such applications. An epoxy terminated polysiloxane; crosslinked with an aminopropyl disiloxane has been developed as a suitable material for the fabrication of optical waveguides by two-photon absorption (TPA). The material fulfils a number of requirements including a good refractive index contrast between the Matrix material and inscribed waveguide, full flexibility and high thermal stability. The Matrix material was characterised by Fourier transform infrared spectroscopy (FTIR) and thermal gravimetric analysis (TGA) The optical waveguides were characterised by phase contrast microscopy, and were directly integrated onto specially designed PCB's by correctly positioning waveguide bundles between optoelectronic components using TPA, making it possible to detect transmitted photocurrents. © 2011 Elsevier Ltd. All rights reserved.

Rajiv Mahajan - One of the best experts on this subject based on the ideXlab platform.

  • challenges in forming successful mixed Matrix membranes with rigid polymeric Materials
    Journal of Applied Polymer Science, 2002
    Co-Authors: Rajiv Mahajan, Michael Schaeffer, Ryan L Burns, William J. Koros
    Abstract:

    Mixed Matrix Materials comprised of molecular sieve domains embedded in processable polymer matrices have the potential to provide membranes with higher permselectivity and equivalent productivity compared to existing membrane Materials. It has been shown that successful mixed Matrix Materials can be formed using relatively low glass transition (Tg) polymers that have a favorable interaction with the sieves. This article extends this earlier work to include the use of more practical rigid Matrix polymers with high Tgs that can ultimately be used in forming high-performance mixed Matrix layers for composite membranes. Initial attempts to form mixed Matrix Materials based on high Tg polymers with a type 4A zeolite resulted in poor adhesion between the polymer and sieve. Correcting this problem was pursued in this study by forming the composite material close to the Tg of the polymer by addition of a plasticizer to match the Matrix Tg with the solvent volatility. Forming the films at elevated temperatures presented substantial challenges, and this work discusses overcoming these challenges in detail. With some modifications in the film casting procedure, successful Materials were achieved. Promising oxygen/nitrogen transport results are presented for these zeolite 4A–Matrimid®/plasticizer membranes, and this data compares favorably with predictions of the well-known Maxwell model for composite systems. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 881–890, 2002

  • mixed Matrix membrane Materials with glassy polymers part 2
    Polymer Engineering and Science, 2002
    Co-Authors: Rajiv Mahajan, William J. Koros
    Abstract:

    Analysis presented in Part 1 of this paper indicated the importance of optimization of the transport properties of the interfacial region to achieve ideal mixed Matrix Materials. This insight is used in this paper to guide mixed Matrix material formation with more conventional gas separation polymers. Conventional gas separation Materials are rigid, and, as seen earlier, lead to the formation of an undesirable interphase under conventional casting techniques. We show in this study that if flexibility can be maintained during membrane formation with a polymer that interacts favorably with the sieve, successful mixed Matrix Materials result, even with rigid polymeric Materials. Flexibility during membrane formation can be achieved by formation of films at temperatures close to the glass transition temperature of the polymer. Moreover, combination of chemical coupling and flexibility during membrane formation produces even more significant improvements in membrane performance. This approach leads to the formation of mixed Matrix material with transport properties exceeding the upper bound currently achieved by conventional membrane Materials. Another approach to form successful mixed Matrix Materials involves tailoring the interface by use of integral chemical linkages that are intrinsically part of the chain backbone. Such linkages appear to tighten the interface sufficiently to prevent “nonselective leakage” along the interface. This approach is demonstrated by directly bonding a reactive polymer onto the sieve surface under proper processing conditions.

  • mixed Matrix membrane Materials with glassy polymers part 1
    Polymer Engineering and Science, 2002
    Co-Authors: Rajiv Mahajan, William J. Koros
    Abstract:

    Mixed Matrix Materials comprising molecular sieve entities embedded in a polymer Matrix can economically increase membrane permselectivity, thereby addressing a key challenge hindering the widespread use of membrane-based gas separations. Prior work has clarified the importance of proper selection of the dispersed sieve phase and the continuous Matrix phase based on their intrinsic transport properties. Proper material selection for the two components, while necessary, is not sufficient since the interfacial contact zone appears to be equally important to achieve optimum transport properties. Specifically, it was found that chemical coupling of the sieve to the polymer can lead to better macroscopic adhesion but to even poorer transport properties than in the absence of the adhesion promoter. This counterintuitive behavior may be attributed to a nanometric region of disturbed packing at the polymer sieve interphase. The poor properties are believed to result from “leakage” of gas molecules along this nanometric interface. The Maxwell model was modified to take into account these complexities and to provide a first order quantification of the nanometric interphase. The analysis indicates that optimization of the transport properties of the interfacial region is key to the formation of ideal mixed Matrix Materials. This approach is used in the second part of this paper to form successful mixed Matrix membrane Materials.

  • Challenges in forming successful mixed Matrix membranes with rigid polymeric Materials
    Journal of Applied Polymer Science, 2002
    Co-Authors: Rajiv Mahajan, Ryan Burns, Michael Schaeffer, William J. Koros
    Abstract:

    Mixed Matrix Materials comprised of molecular sieve domains embedded in processable polymer matrices have the potential to provide membranes with higher permselectivity and equivalent productivity compared to existing membrane Materials. It has been shown that successful mixed Matrix Materials can be formed using relatively low glass transition (T-g) polymers that have a favorable interaction with the sieves. This article extends this earlier work to include the use of more practical rigid Matrix polymers with high T(g)s that can ultimately be used in forming high-performance mixed Matrix layers for composite membranes. Initial attempts to form mixed Matrix Materials based on high T-g polymers with a type 4A zeolite resulted in poor adhesion between the polymer and sieve. Correcting composite material close to the T-g of the polymer by addition of a plasticizer to match the Matrix T-g with the solvent volatility. Forming the films at elevated temperatures presented substantial challenges, and this work discusses overcoming these challenges in detail. With some modifications in the film casting procedure, successful Materials were achieved. Promising oxygen/nitrogen transport results are presented for these zeolite 4A-Matrimid(R)/plasticizer membranes, and this data compares favorably with predictions of the well-known Maxwell model for composite systems. (C) 2002 Wiley Periodicals, Inc.

Rachel Woods - One of the best experts on this subject based on the ideXlab platform.

  • Epoxy silicone based Matrix Materials for two-photon patterning of optical waveguides
    Polymer, 2011
    Co-Authors: Rachel Woods, Sonja Feldbacher, Valentin Satzinger, G. Langer, Volker Schmidt, Wolfgang Kern
    Abstract:

    Abstract 3D polymeric optical waveguides play an intrinsic role in a rapidly developing area of broadband communications. Advances in the field of electronics means there is a greater demand for higher speeds, larger data storage, smaller components and the improvement in the design of integrated optical circuits. Two-photon photopolymerisation (2PP) is a promising three-dimensional microfabrication technique, which can be used to produce structures in the sub-micron region. With the use of near-infrared (NIR) lasers, 3D optical waveguides can be fabricated in polymer-based Matrix Materials, based on the increase of the refractive index in the vicinity of the laser focus. The development of a new polysiloxane material, used in the study of the integration of optical interconnects on printed circuit boards is presented. The desirable properties of epoxy functional silicones crosslinked with diamines deem them suitable for such applications. An epoxy terminated polysiloxane; crosslinked with an aminopropyl disiloxane has been developed as a suitable material for the fabrication of optical waveguides by two-photon absorption (TPA). The material fulfils a number of requirements including a good refractive index contrast between the Matrix material and inscribed waveguide, full flexibility and high thermal stability. The Matrix material was characterised by Fourier transform infrared spectroscopy (FTIR) and thermal gravimetric analysis (TGA) The optical waveguides were characterised by phase contrast microscopy, and were directly integrated onto specially designed PCB’s by correctly positioning waveguide bundles between optoelectronic components using TPA, making it possible to detect transmitted photocurrents.

  • Epoxy silicone based Matrix Materials for two-photon patterning of optical waveguides
    Polymer, 2011
    Co-Authors: Rachel Woods, Sonja Feldbacher, Valentin Satzinger, G. Langer, Volker Schmidt, Wolfgang Kern
    Abstract:

    3D polymeric optical waveguides play an intrinsic role in a rapidly developing area of broadband communications. Advances in the field of electronics means there is a greater demand for higher speeds, larger data storage, smaller components and the improvement in the design of integrated optical circuits. Two-photon photopolymerisation (2PP) is a promising three-dimensional microfabrication technique, which can be used to produce structures in the sub-micron region. With the use of near-infrared (NIR) lasers, 3D optical waveguides can be fabricated in polymer-based Matrix Materials, based on the increase of the refractive index in the vicinity of the laser focus. The development of a new polysiloxane material, used in the study of the integration of optical interconnects on printed circuit boards is presented. The desirable properties of epoxy functional silicones crosslinked with diamines deem them suitable for such applications. An epoxy terminated polysiloxane; crosslinked with an aminopropyl disiloxane has been developed as a suitable material for the fabrication of optical waveguides by two-photon absorption (TPA). The material fulfils a number of requirements including a good refractive index contrast between the Matrix material and inscribed waveguide, full flexibility and high thermal stability. The Matrix material was characterised by Fourier transform infrared spectroscopy (FTIR) and thermal gravimetric analysis (TGA) The optical waveguides were characterised by phase contrast microscopy, and were directly integrated onto specially designed PCB's by correctly positioning waveguide bundles between optoelectronic components using TPA, making it possible to detect transmitted photocurrents. © 2011 Elsevier Ltd. All rights reserved.

G. Langer - One of the best experts on this subject based on the ideXlab platform.

  • Epoxy silicone based Matrix Materials for two-photon patterning of optical waveguides
    Polymer, 2011
    Co-Authors: Rachel Woods, Sonja Feldbacher, Valentin Satzinger, G. Langer, Volker Schmidt, Wolfgang Kern
    Abstract:

    Abstract 3D polymeric optical waveguides play an intrinsic role in a rapidly developing area of broadband communications. Advances in the field of electronics means there is a greater demand for higher speeds, larger data storage, smaller components and the improvement in the design of integrated optical circuits. Two-photon photopolymerisation (2PP) is a promising three-dimensional microfabrication technique, which can be used to produce structures in the sub-micron region. With the use of near-infrared (NIR) lasers, 3D optical waveguides can be fabricated in polymer-based Matrix Materials, based on the increase of the refractive index in the vicinity of the laser focus. The development of a new polysiloxane material, used in the study of the integration of optical interconnects on printed circuit boards is presented. The desirable properties of epoxy functional silicones crosslinked with diamines deem them suitable for such applications. An epoxy terminated polysiloxane; crosslinked with an aminopropyl disiloxane has been developed as a suitable material for the fabrication of optical waveguides by two-photon absorption (TPA). The material fulfils a number of requirements including a good refractive index contrast between the Matrix material and inscribed waveguide, full flexibility and high thermal stability. The Matrix material was characterised by Fourier transform infrared spectroscopy (FTIR) and thermal gravimetric analysis (TGA) The optical waveguides were characterised by phase contrast microscopy, and were directly integrated onto specially designed PCB’s by correctly positioning waveguide bundles between optoelectronic components using TPA, making it possible to detect transmitted photocurrents.

  • Epoxy silicone based Matrix Materials for two-photon patterning of optical waveguides
    Polymer, 2011
    Co-Authors: Rachel Woods, Sonja Feldbacher, Valentin Satzinger, G. Langer, Volker Schmidt, Wolfgang Kern
    Abstract:

    3D polymeric optical waveguides play an intrinsic role in a rapidly developing area of broadband communications. Advances in the field of electronics means there is a greater demand for higher speeds, larger data storage, smaller components and the improvement in the design of integrated optical circuits. Two-photon photopolymerisation (2PP) is a promising three-dimensional microfabrication technique, which can be used to produce structures in the sub-micron region. With the use of near-infrared (NIR) lasers, 3D optical waveguides can be fabricated in polymer-based Matrix Materials, based on the increase of the refractive index in the vicinity of the laser focus. The development of a new polysiloxane material, used in the study of the integration of optical interconnects on printed circuit boards is presented. The desirable properties of epoxy functional silicones crosslinked with diamines deem them suitable for such applications. An epoxy terminated polysiloxane; crosslinked with an aminopropyl disiloxane has been developed as a suitable material for the fabrication of optical waveguides by two-photon absorption (TPA). The material fulfils a number of requirements including a good refractive index contrast between the Matrix material and inscribed waveguide, full flexibility and high thermal stability. The Matrix material was characterised by Fourier transform infrared spectroscopy (FTIR) and thermal gravimetric analysis (TGA) The optical waveguides were characterised by phase contrast microscopy, and were directly integrated onto specially designed PCB's by correctly positioning waveguide bundles between optoelectronic components using TPA, making it possible to detect transmitted photocurrents. © 2011 Elsevier Ltd. All rights reserved.