Regensburg 2022 – wissenschaftliches Programm
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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 33: Focus Session: Soft Matter and Nanocomposites: New Opportunities with Advanced Neutron Sources 1
CPP 33.2: Vortrag
Donnerstag, 8. September 2022, 10:00–10:15, H38
Molecular weight dependent dynamics of polymers grafted on nanoparticles. — •Aakash Sharma1, Margarita Kruteva1, Michaela Zamponi2, Sascha Ehlert1, Dieter Richter1, and Stephan Förster1 — 1Forschungszentrum Jülich GmbH, Jülich Centre for Neutron Science (JCNS-1: Neutron Scattering and Biological Matter), 52425 Jülich, Germany — 2Forschungszentrum Jülich GmbH, Jülich Centre for Neutron Science at MLZ, Lichtenbergstraße 1, 85748 Garching, Germany
Grafting polymer chains on nanoparticles prevents their undesired aggregation leading to improved properties. Whereas, grafting induces inevitable alteration in the dynamics of polymer chains, which affects macroscopic properties e.g. viscoelasticity. It has been established that the polymer chain dynamics is retarded in grafted chains. However, literature lacks consensus on whether the segmental dynamics of grafted chains is accelerated or retarded. We study the segmental dynamics of polyisoprene grafted on spherical nanoparticles using neutron backscattering. The analysis of relaxation times led to the conclusions: (i) Low molecular weight (MW) grafted polymer display reduced local relaxation (ii) At high MW and equal grafting density faster segmental dynamics than the free polymer is observed. We prove that these conflicting results are seemingly artifacts of the traditional analysis method. We invoke an elegant methodology and show that the underlying physics of grafted polymer is unchanged. However, spatial variation of the relaxation times across the grafted chain causes the average dynamics to transition with molecular weight.