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 .
 A. Mujtaba et al., ACS Macro Lett. 2014, 3, 481  A. Papon et al., Phys. Rev. Lett. 2012, 108, 065702  Y. Golitsyn et al., J. Chem. Phys. 2017, 146, 203303  S. M. Oh et al., Phys. Rev. Lett. 2019, 123, 167801  H. Schneider et al., Macromolecules 2017, 50, 8598