Dresden 2020 – wissenschaftliches Programm
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CPP 85.1: Hauptvortrag
Donnerstag, 19. März 2020, 09:30–10:00, ZEU 222
Molecular view on polymers adsorbed on nanoparticle surfaces — Mozhdeh Abbasi1, Sol Mi Oh2, So Youn Kim2, and •Kay Saalwächter1 — 1Inst. f. Physik - NMR, Martin-Luther-Univ. Halle-Wittenberg, Halle (Saale), Germany — 2School of Energy and Chemical Engineering, UNIST, Ulsan, Republic of Korea
The reinforcement effect of nanoparticles in a polymer matrix is related to an interphase with modified properties . Previous results support a consensus picture of adsorbed components with locally increased Tg and gradient zone of a few nm . This talk focuses on more recent results, mostly obtained by proton low-resolution NMR as a probe of the segmental dynamics, that challenge the generality of this picture. In the system poly(ethylene oxide)-silica, we do find strongly immobilized (yet intrinsically mobile) components forming a layer of up to 2 nm thickness around the particles , but the layer thickness is temperature-independent and is governed by a non-equilibrium process in dependence of end groups  and preparation conditions , and also of the curvature of the particles. Spin-diffusion NMR experiments, which probe the size of nanometric domains with distinct mobility, indicate that the smooth-mobility-gradient picture of the ``glassy layer'' must be replaced by a scenario ruled by dynamic heterogeneities associated with the increased glass transition .
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