Universal polymeric-to-colloidal transition in melts of hairy nanoparticles
Résumé
Two different classes of hairy self-suspended nanoparticles in the melt state, polymer-grafted nanoparticles (GNPs) and star polymers, are shown to display universal dynamic behavior across a broad range of parameter space. Linear viscoelastic measurements on well-characterized silicapoly(methyl acrylate) GNPs at fixed core radius (Rcore) and grafting density (or number of arms f), but varying arm degree of polymerization (Narm) show two distinctly different regimes of response. A colloidal Regime I at small Narm (large core volume fraction), with a predominant low-frequency solid-like colloidal plateau and ultraslow relaxation, and a polymeric Regime II at large Narm (small core volume fractions), with a response dominated by the star-like relaxation of partially interpenetrated arms. The transition between the two regimes is marked by a cross-over where both polymeric and colloidal modes are discerned albeit without a distinct colloidal plateau.
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2022-10-14 GNP revision 2021 acs nano_with SI.pdf (1013.66 Ko)
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