0000000000785521

AUTHOR

H.d. Middendorf

showing 2 related works from this author

QENS from polymer aggregates in supercritical CO2

2000

Abstract We report QENS measurements from PS-b-PFOA aggregates in supercritical CO2. Line shapes are dominated by localized diffusive modes and segmental dynamics of the anchored, finite-length PFOA chains. For Q⩽0.6 A−1, we obtain effective diffusion coefficients of ≅0.8 10−6 cm2/s. At higher Q, a single component is not sufficient as shown by excess intensity on the flanks. For Q⩾1.5 A−1, the wings reflect contributions due to a distribution of faster, more localized chain modes.

chemistry.chemical_classificationMaterials scienceSingle componentIncoherent scatterPolymerCondensed Matter PhysicsSupercritical fluidElectronic Optical and Magnetic MaterialsNuclear magnetic resonancechemistryChemical physicsElectrical and Electronic EngineeringDiffusion (business)Intensity (heat transfer)Line (formation)Physica B: Condensed Matter
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QENS from polymeric micelles in supercritical CO[sub 2]

2000

We report QENS measurements from PS-b-PFOA aggregates in supercritical CO2. These consist of dense cores of CO2-insoluble polystyrene surrounded by a ‘corona’ of PFOA surfactant molecules whose CO2-philic groups interface with supercritical CO2. Lineshapes are dominated by localized diffusive modes and segmental dynamics of the anchored, finite-length PFOA chains. For Q∼0.6 A−1, we obtain effective diffusion coefficients of ≈0.8×10−6 cm2/sec. At higher Q, a single component is not sufficient as shown by excess intensity on the flanks. For Q>1.5 A−1, the wings reflect contributions due to a distribution of faster, more localized chain modes.

chemistry.chemical_classificationchemistry.chemical_compoundCrystallographychemistryChemical physicsDiffusionMoleculePolymerPolystyreneCrystal structureNeutron scatteringSupercritical fluidPhase diagramAIP Conference Proceedings
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