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Dan Neumann, National Institute of Standards and Technology, DMR 0944772

Multiscale structure, interfacial cohesion, adsorbed layers, and thermodynamics in dense polymer-nanoparticle mixtures. Dan Neumann, National Institute of Standards and Technology, DMR 0944772.

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Dan Neumann, National Institute of Standards and Technology, DMR 0944772

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  1. Multiscale structure, interfacial cohesion, adsorbed layers, and thermodynamics in dense polymer-nanoparticle mixtures Dan Neumann, National Institute of Standards and Technology, DMR 0944772 Particle stability in nanocomposites can be understood in terms of the strength of attraction between polymer segments and particles (epc). 40 nm diameter silica nanoparticles are suspended in polyethylene glycol 400 and H2O/D2O mixtures. In the system, there are three different interactions present (particle-particle, particle-polymer segment and polymer segment-polymer segment interactions). The partial structure factors resulting from these interactions have been obtained from contrast matching experiments using the CHRNS-supported small angle neutron scattering instrument. Extracted partial structure factors are compared with Polymer Reference Interaction Site Model predictions (shown as curves), using different epcvalues. epc is found to be 0.45 kT from all Scc, Spc and Spp. (left) Scattered intensity at a fixed polymer concentration and particle volume fraction (fc), with varying D2O/H2O ratios (right), extracting all partial structure factors at various fc One can obtain information about the origin of steric stabilization from partial structure factors and estimate the thickness of polymer adsorption in dense polymer-nanoparticle mixtures. Polymer shell form factor from the adsorbed polymer segments on a particle. S. Kim, K. S. Schweizer and C. F. Zukoski, Phys. Rev. Lett., 107, 225504 (2011).

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