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

  • unraveling the Polymer chain Adsorbed constrained interfacial region on an atomistically thin carbon sheet
    Journal of Physical Chemistry B, 2019
    Co-Authors: Sanjay Kumar, Venkat Padmanabhan, Kishore Kumar Sriramoju, Vinod K. Aswal, G. Harikrishnan
    Abstract:

    Confinement of graphene and its functional derivatives in synthetic and biomacromolecules has been widely demonstrated recently to manifest in several multiscale phenomena in their mixtures. However, the intricate Adsorbed interfacial region formed between Polymer chains and a single layer of atomistically thin carbon sheet hitherto evaded an understanding of its nature and characteristics. Here, we reveal the structure of this constrained region and estimate the thickness of the Adsorbed Polymer layer on a single layer of an atomistically thin graphene oxide sheet using both direct experiments and molecular dynamics simulations. We use small-angle neutron scattering on a model multicomponent mixture formed by an adsorbing Polymer, graphene oxide, and solvent for revealing the structure of the constrained interfacial region. We quantify the intricate Adsorbed Polymer layer thickness on a single layer of atomistically thin graphene oxide sheet by Euclidean approximation of the experimentally observed self-similar interfacial structure. The state of Polymer chain random walk and influence of unAdsorbed chains under experimental conditions are investigated and juxtaposed against the accuracy of this quantification. For long-chain Polymers, the Adsorbed layer thickness increases with increasing Polymer molecular weight and shows a scaling relationship δ ∼ Rg0.22 with the Polymer radius of gyration. For short-chain Polymers, the thickness is nearly independent of molecular weight and shows a scaling relationship δ ∼ 0.6 Rg0.22. Coarse-grained molecular dynamics simulations performed on a model system similar to experiments qualitatively ratify the experimentally observed molecular weight-thickness relationship. Simulations show no discernible scaling relationship between radius of gyration and Adsorbed layer thickness for low-molecular-weight Polymers but show a consistent scaling δ ∼ Rg for high-molecular-weight Polymers. A comparison between results from experiments and simulations indicates a discerning pathway in deciphering interface-governed multiscale phenomena in mixtures of adsorbing macromolecules with graphene and its functional derivatives.

  • Unraveling the Polymer Chain-Adsorbed Constrained Interfacial Region on an Atomistically Thin Carbon Sheet
    2019
    Co-Authors: Sanjay Kumar, Venkat Padmanabhan, Kishore Kumar Sriramoju, Vinod K. Aswal, G. Harikrishnan
    Abstract:

    Confinement of graphene and its functional derivatives in synthetic and biomacromolecules has been widely demonstrated recently to manifest in several multiscale phenomena in their mixtures. However, the intricate Adsorbed interfacial region formed between Polymer chains and a single layer of atomistically thin carbon sheet hitherto evaded an understanding of its nature and characteristics. Here, we reveal the structure of this constrained region and estimate the thickness of the Adsorbed Polymer layer on a single layer of an atomistically thin graphene oxide sheet using both direct experiments and molecular dynamics simulations. We use small-angle neutron scattering on a model multicomponent mixture formed by an adsorbing Polymer, graphene oxide, and solvent for revealing the structure of the constrained interfacial region. We quantify the intricate Adsorbed Polymer layer thickness on a single layer of atomistically thin graphene oxide sheet by Euclidean approximation of the experimentally observed self-similar interfacial structure. The state of Polymer chain random walk and influence of unAdsorbed chains under experimental conditions are investigated and juxtaposed against the accuracy of this quantification. For long-chain Polymers, the Adsorbed layer thickness increases with increasing Polymer molecular weight and shows a scaling relationship δ ∼ Rg0.22 with the Polymer radius of gyration. For short-chain Polymers, the thickness is nearly independent of molecular weight and shows a scaling relationship δ ∼ 0.6Rg0.22. Coarse-grained molecular dynamics simulations performed on a model system similar to experiments qualitatively ratify the experimentally observed molecular weight–thickness relationship. Simulations show no discernible scaling relationship between radius of gyration and Adsorbed layer thickness for low-molecular-weight Polymers but show a consistent scaling δ ∼ Rg for high-molecular-weight Polymers. A comparison between results from experiments and simulations indicates a discerning pathway in deciphering interface-governed multiscale phenomena in mixtures of adsorbing macromolecules with graphene and its functional derivatives

Venkat Padmanabhan - One of the best experts on this subject based on the ideXlab platform.

  • unraveling the Polymer chain Adsorbed constrained interfacial region on an atomistically thin carbon sheet
    Journal of Physical Chemistry B, 2019
    Co-Authors: Sanjay Kumar, Venkat Padmanabhan, Kishore Kumar Sriramoju, Vinod K. Aswal, G. Harikrishnan
    Abstract:

    Confinement of graphene and its functional derivatives in synthetic and biomacromolecules has been widely demonstrated recently to manifest in several multiscale phenomena in their mixtures. However, the intricate Adsorbed interfacial region formed between Polymer chains and a single layer of atomistically thin carbon sheet hitherto evaded an understanding of its nature and characteristics. Here, we reveal the structure of this constrained region and estimate the thickness of the Adsorbed Polymer layer on a single layer of an atomistically thin graphene oxide sheet using both direct experiments and molecular dynamics simulations. We use small-angle neutron scattering on a model multicomponent mixture formed by an adsorbing Polymer, graphene oxide, and solvent for revealing the structure of the constrained interfacial region. We quantify the intricate Adsorbed Polymer layer thickness on a single layer of atomistically thin graphene oxide sheet by Euclidean approximation of the experimentally observed self-similar interfacial structure. The state of Polymer chain random walk and influence of unAdsorbed chains under experimental conditions are investigated and juxtaposed against the accuracy of this quantification. For long-chain Polymers, the Adsorbed layer thickness increases with increasing Polymer molecular weight and shows a scaling relationship δ ∼ Rg0.22 with the Polymer radius of gyration. For short-chain Polymers, the thickness is nearly independent of molecular weight and shows a scaling relationship δ ∼ 0.6 Rg0.22. Coarse-grained molecular dynamics simulations performed on a model system similar to experiments qualitatively ratify the experimentally observed molecular weight-thickness relationship. Simulations show no discernible scaling relationship between radius of gyration and Adsorbed layer thickness for low-molecular-weight Polymers but show a consistent scaling δ ∼ Rg for high-molecular-weight Polymers. A comparison between results from experiments and simulations indicates a discerning pathway in deciphering interface-governed multiscale phenomena in mixtures of adsorbing macromolecules with graphene and its functional derivatives.

  • Unraveling the Polymer Chain-Adsorbed Constrained Interfacial Region on an Atomistically Thin Carbon Sheet
    2019
    Co-Authors: Sanjay Kumar, Venkat Padmanabhan, Kishore Kumar Sriramoju, Vinod K. Aswal, G. Harikrishnan
    Abstract:

    Confinement of graphene and its functional derivatives in synthetic and biomacromolecules has been widely demonstrated recently to manifest in several multiscale phenomena in their mixtures. However, the intricate Adsorbed interfacial region formed between Polymer chains and a single layer of atomistically thin carbon sheet hitherto evaded an understanding of its nature and characteristics. Here, we reveal the structure of this constrained region and estimate the thickness of the Adsorbed Polymer layer on a single layer of an atomistically thin graphene oxide sheet using both direct experiments and molecular dynamics simulations. We use small-angle neutron scattering on a model multicomponent mixture formed by an adsorbing Polymer, graphene oxide, and solvent for revealing the structure of the constrained interfacial region. We quantify the intricate Adsorbed Polymer layer thickness on a single layer of atomistically thin graphene oxide sheet by Euclidean approximation of the experimentally observed self-similar interfacial structure. The state of Polymer chain random walk and influence of unAdsorbed chains under experimental conditions are investigated and juxtaposed against the accuracy of this quantification. For long-chain Polymers, the Adsorbed layer thickness increases with increasing Polymer molecular weight and shows a scaling relationship δ ∼ Rg0.22 with the Polymer radius of gyration. For short-chain Polymers, the thickness is nearly independent of molecular weight and shows a scaling relationship δ ∼ 0.6Rg0.22. Coarse-grained molecular dynamics simulations performed on a model system similar to experiments qualitatively ratify the experimentally observed molecular weight–thickness relationship. Simulations show no discernible scaling relationship between radius of gyration and Adsorbed layer thickness for low-molecular-weight Polymers but show a consistent scaling δ ∼ Rg for high-molecular-weight Polymers. A comparison between results from experiments and simulations indicates a discerning pathway in deciphering interface-governed multiscale phenomena in mixtures of adsorbing macromolecules with graphene and its functional derivatives

Sanjay Kumar - One of the best experts on this subject based on the ideXlab platform.

  • unraveling the Polymer chain Adsorbed constrained interfacial region on an atomistically thin carbon sheet
    Journal of Physical Chemistry B, 2019
    Co-Authors: Sanjay Kumar, Venkat Padmanabhan, Kishore Kumar Sriramoju, Vinod K. Aswal, G. Harikrishnan
    Abstract:

    Confinement of graphene and its functional derivatives in synthetic and biomacromolecules has been widely demonstrated recently to manifest in several multiscale phenomena in their mixtures. However, the intricate Adsorbed interfacial region formed between Polymer chains and a single layer of atomistically thin carbon sheet hitherto evaded an understanding of its nature and characteristics. Here, we reveal the structure of this constrained region and estimate the thickness of the Adsorbed Polymer layer on a single layer of an atomistically thin graphene oxide sheet using both direct experiments and molecular dynamics simulations. We use small-angle neutron scattering on a model multicomponent mixture formed by an adsorbing Polymer, graphene oxide, and solvent for revealing the structure of the constrained interfacial region. We quantify the intricate Adsorbed Polymer layer thickness on a single layer of atomistically thin graphene oxide sheet by Euclidean approximation of the experimentally observed self-similar interfacial structure. The state of Polymer chain random walk and influence of unAdsorbed chains under experimental conditions are investigated and juxtaposed against the accuracy of this quantification. For long-chain Polymers, the Adsorbed layer thickness increases with increasing Polymer molecular weight and shows a scaling relationship δ ∼ Rg0.22 with the Polymer radius of gyration. For short-chain Polymers, the thickness is nearly independent of molecular weight and shows a scaling relationship δ ∼ 0.6 Rg0.22. Coarse-grained molecular dynamics simulations performed on a model system similar to experiments qualitatively ratify the experimentally observed molecular weight-thickness relationship. Simulations show no discernible scaling relationship between radius of gyration and Adsorbed layer thickness for low-molecular-weight Polymers but show a consistent scaling δ ∼ Rg for high-molecular-weight Polymers. A comparison between results from experiments and simulations indicates a discerning pathway in deciphering interface-governed multiscale phenomena in mixtures of adsorbing macromolecules with graphene and its functional derivatives.

  • Unraveling the Polymer Chain-Adsorbed Constrained Interfacial Region on an Atomistically Thin Carbon Sheet
    2019
    Co-Authors: Sanjay Kumar, Venkat Padmanabhan, Kishore Kumar Sriramoju, Vinod K. Aswal, G. Harikrishnan
    Abstract:

    Confinement of graphene and its functional derivatives in synthetic and biomacromolecules has been widely demonstrated recently to manifest in several multiscale phenomena in their mixtures. However, the intricate Adsorbed interfacial region formed between Polymer chains and a single layer of atomistically thin carbon sheet hitherto evaded an understanding of its nature and characteristics. Here, we reveal the structure of this constrained region and estimate the thickness of the Adsorbed Polymer layer on a single layer of an atomistically thin graphene oxide sheet using both direct experiments and molecular dynamics simulations. We use small-angle neutron scattering on a model multicomponent mixture formed by an adsorbing Polymer, graphene oxide, and solvent for revealing the structure of the constrained interfacial region. We quantify the intricate Adsorbed Polymer layer thickness on a single layer of atomistically thin graphene oxide sheet by Euclidean approximation of the experimentally observed self-similar interfacial structure. The state of Polymer chain random walk and influence of unAdsorbed chains under experimental conditions are investigated and juxtaposed against the accuracy of this quantification. For long-chain Polymers, the Adsorbed layer thickness increases with increasing Polymer molecular weight and shows a scaling relationship δ ∼ Rg0.22 with the Polymer radius of gyration. For short-chain Polymers, the thickness is nearly independent of molecular weight and shows a scaling relationship δ ∼ 0.6Rg0.22. Coarse-grained molecular dynamics simulations performed on a model system similar to experiments qualitatively ratify the experimentally observed molecular weight–thickness relationship. Simulations show no discernible scaling relationship between radius of gyration and Adsorbed layer thickness for low-molecular-weight Polymers but show a consistent scaling δ ∼ Rg for high-molecular-weight Polymers. A comparison between results from experiments and simulations indicates a discerning pathway in deciphering interface-governed multiscale phenomena in mixtures of adsorbing macromolecules with graphene and its functional derivatives

Charles F Zukoski - One of the best experts on this subject based on the ideXlab platform.

  • multiscale structure interfacial cohesion Adsorbed layers and thermodynamics in dense Polymer nanoparticle mixtures
    Physical Review Letters, 2011
    Co-Authors: So Youn Kim, Kenneth S Schweizer, Charles F Zukoski
    Abstract:

    We establish the existence and size of Adsorbed Polymer layers in miscible dense nanocomposites and their consequences on microstructure and the bulk modulus. Using contrast-matching small-angle neutron scattering to characterize all partial collective structure factors of Polymers, particles, and their interface, we demonstrate qualitative failure of the random phase approximation, accuracy of the Polymer reference site interaction model theory, ability to deduce the Adsorbed Polymer layer thickness, and high sensitivity of the nanocomposite bulk modulus to interfacial cohesion.

  • concentration fluctuations local order and the collective structure of Polymer nanocomposites
    Macromolecules, 2009
    Co-Authors: Lisa M Hall, Charles F Zukoski, Benjamin J Anderson, Kenneth S Schweizer
    Abstract:

    A combined theory−experiment analysis of adsorbing Polymer mediated structural reorganization of silica nanoparticles in equilibrated and miscible poly(ethylene oxide) (PEO) and polytetrahydrofuran (PTHF) nanocomposites is presented. Quantitative comparison of microscopic liquid state theory calculations with small-angle X-ray scattering experiments demonstrate the theoretical approach properly accounts for the effects of Adsorbed Polymer layers on nanoparticle concentration fluctuations over all length scales for a wide range of volume fractions and interfacial cohesion strengths. The mixture total packing fraction is increased as particles are added to the Polymer melt in order to account for equation-of-state effects which are important at very high filler loadings. A distinctive microphase separation like peak in the collective Polymer structure factor is predicted. Nanoparticle potential of mean force calculations suggest a criterion for the onset of depletion or bridging induced kinetic gelation whi...

Jayne M. Lawrence - One of the best experts on this subject based on the ideXlab platform.

  • characterization of Polymer adsorption onto drug nanoparticles using depletion measurements and small angle neutron scattering
    Molecular Pharmaceutics, 2013
    Co-Authors: Daniel J Goodwin, Shadi Sepassi, Stephen M. King, Simon J. Holland, Luigi G. Martini, Jayne M. Lawrence
    Abstract:

    Production of Polymer and/or surfactant-coated crystalline nanoparticles of water-insoluble drugs (nanosuspensions) using wet bead milling is an important formulation approach to improve the bioavailability of said compounds. Despite the fact that there are a number of nanosuspensions on the market, there is still a deficiency in the characterization of these nanoparticles where further understanding may lead to the rational selection of Polymer/surfactant. To this end small-angle neutron scattering (SANS) measurements were performed on drug nanoparticles milled in the presence of a range of Polymers of varying molecular weight. Isotopic substitution of the aqueous solvent to match the scattering length density of the drug nanoparticles (i.e., the technique of contrast matching) meant that neutron scattering resulted only from the Adsorbed Polymer layer. The layer thickness and amount of hydroxypropylcellulose Adsorbed on nabumetone nanoparticles derived from fitting the SANS data to both model-independen...

  • Characterization of Polymer Adsorption onto Drug Nanoparticles Using Depletion Measurements and Small-Angle Neutron Scattering
    2013
    Co-Authors: Daniel J. Goodwin, Shadi Sepassi, Stephen M. King, Simon J. Holland, Luigi G. Martini, Jayne M. Lawrence
    Abstract:

    Production of Polymer and/or surfactant-coated crystalline nanoparticles of water-insoluble drugs (nanosuspensions) using wet bead milling is an important formulation approach to improve the bioavailability of said compounds. Despite the fact that there are a number of nanosuspensions on the market, there is still a deficiency in the characterization of these nanoparticles where further understanding may lead to the rational selection of Polymer/surfactant. To this end small-angle neutron scattering (SANS) measurements were performed on drug nanoparticles milled in the presence of a range of Polymers of varying molecular weight. Isotopic substitution of the aqueous solvent to match the scattering length density of the drug nanoparticles (i.e., the technique of contrast matching) meant that neutron scattering resulted only from the Adsorbed Polymer layer. The layer thickness and amount of hydroxypropylcellulose Adsorbed on nabumetone nanoparticles derived from fitting the SANS data to both model-independent and model dependent volume fraction profiles were insensitive to Polymer molecular weight over the range Mv = 47–112 kg/mol, indicating that the Adsorbed layer is relatively flat but with tails extending up to approximately 23 nm. The constancy of the absorbed amount is in agreement with the adsorption isotherm determined by measuring Polymer depletion from solution in the presence of the nanoparticles. Insensitivity to Polymer molecular weight was similarly determined using SANS measurements of nabumetone or halofantrine nanoparticles stabilized with hydroxypropylmethylcellulose or poly­(vinylpyrrolidone). Additionally SANS studies revealed the amount Adsorbed, and the thickness of the Polymer layer was dependent on both the nature of the Polymer and drug particle surface. The insensitivity of the Adsorbed Polymer layer to Polymer molecular weight has important implications for the production of nanoparticles, suggesting that lower molecular weight Polymers should be used when preparing nanoparticles by wet bead milling since nanoparticle formation is more rapid but with no likely consequence on the resultant physical stability of the nanoparticles