(193w) Self-Diffusion of Polymer-Grafted Nanoparticles In Polymer Melts | AIChE

(193w) Self-Diffusion of Polymer-Grafted Nanoparticles In Polymer Melts

Authors 

Green, D. - Presenter, University of Virginia
McEwan, M. - Presenter, University of Virginia


We probed the dynamics of uniform dispersions of polymer-grafted nanoparticles in polymer melts with x-ray photon correlation spectroscopy (XPCS). Analysis of the characteristic relaxation times revealed Brownian diffusion below the entanglement molecular weight of the melt polymer, and inhibited dynamics above the entanglement molecular weight.  The self-diffusivity of the nanoparticles, i.e., diffusivity of the nanoparticles relative to that at infinite dilution was slower in the lower molecular weight melt due to the greater stretching of the graft polymer. In accord with theory, nanoparticle self-diffusivities in melts of varying molecular weights scale with respect to the effective volume fraction when considering the particle core and polymer brush as a hard sphere. Further, we show a correspondence between the scaled nanoparticle diffusivity and the low-shear viscosity – the first time this has been carried out in polymer melts.

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