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Molecular ring rotation in poly(vinylferrocene)

Appel, Markus and Frick, Bernhard and Elbert, Johannes and Gallei, Markus and Stühn, B. (2016):
Molecular ring rotation in poly(vinylferrocene).
In: PHYSICAL CHEMISTRY CHEMICAL PHYSICS, ROYAL SOC CHEMISTRY, pp. 28973-28981, 18, (41), ISSN 1463-9076, [Article]

Abstract

We investigate the ring rotation dynamics in poly(vinylferrocene) (PVFc) using incoherent neutron spectroscopy. PVFc contains ferrocene units laterally attached to a polymer backbone, allowing for one cyclopentadienyl ring of the organometallic sandwich structure of ferrocene to undergo rotational jump diffusion. The barrier of rotation is found to be broadly distributed, but the dynamics can be well described using a rotation rate distribution model which is well known from the description of methyl group rotation in glassy polymers. As necessary information for the analysis of quasielastic scattering data, we measure the static structure factor of the polymer using polarized neutron diffraction. Neutron time-of-flight and backscattering data are then combined and consistently modeled over the large temperature range from 80 K to 350 K yielding an Arrhenius behavior of the jump rate distribution. The mean value of potential barrier distribution is found to be < E-A > = 9.61(2) kJ mol(-1) with a root mean square width of sigma(E) = 3.12(1) kJ mol(-1), being the result of superposition of constant intramolecular and heterogeneous intermolecular rotational barriers.

Item Type: Article
Erschienen: 2016
Creators: Appel, Markus and Frick, Bernhard and Elbert, Johannes and Gallei, Markus and Stühn, B.
Title: Molecular ring rotation in poly(vinylferrocene)
Language: Afar
Abstract:

We investigate the ring rotation dynamics in poly(vinylferrocene) (PVFc) using incoherent neutron spectroscopy. PVFc contains ferrocene units laterally attached to a polymer backbone, allowing for one cyclopentadienyl ring of the organometallic sandwich structure of ferrocene to undergo rotational jump diffusion. The barrier of rotation is found to be broadly distributed, but the dynamics can be well described using a rotation rate distribution model which is well known from the description of methyl group rotation in glassy polymers. As necessary information for the analysis of quasielastic scattering data, we measure the static structure factor of the polymer using polarized neutron diffraction. Neutron time-of-flight and backscattering data are then combined and consistently modeled over the large temperature range from 80 K to 350 K yielding an Arrhenius behavior of the jump rate distribution. The mean value of potential barrier distribution is found to be < E-A > = 9.61(2) kJ mol(-1) with a root mean square width of sigma(E) = 3.12(1) kJ mol(-1), being the result of superposition of constant intramolecular and heterogeneous intermolecular rotational barriers.

Journal or Publication Title: PHYSICAL CHEMISTRY CHEMICAL PHYSICS
Volume: 18
Number: 41
Place of Publication: THOMAS GRAHAM HOUSE, SCIENCE PARK, MILTON RD, CAMBRIDGE CB4 0WF, CAMBS, ENGLAND
Publisher: ROYAL SOC CHEMISTRY
Divisions: 05 Department of Physics > Institute for condensed matter physics > Experimental Condensed Matter Physics
05 Department of Physics > Institute for condensed matter physics
05 Department of Physics
Event Location: THOMAS GRAHAM HOUSE, SCIENCE PARK, MILTON RD, CAMBRIDGE CB4 0WF, CAMBS, ENGLAND
Date Deposited: 30 Jan 2017 12:10
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