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@ARTICLE{Holler:858954,
author = {Holler, Stefan and Moreno, Angel J. and Zamponi, Michaela
and Bačová, Petra and Willner, Lutz and Iatrou, Hermis and
Falus, Peter and Richter, Dieter},
title = {{T}he {R}ole of the {F}unctionality in the {B}ranch {P}oint
{M}otion in {S}ymmetric {S}tar {P}olymers: {A} {C}ombined
{S}tudy by {S}imulations and {N}eutron {S}pin {E}cho
{S}pectroscopy},
journal = {Macromolecules},
volume = {51},
number = {1},
issn = {1520-5835},
address = {Washington, DC},
publisher = {Soc.},
reportid = {FZJ-2018-07780},
pages = {242 - 253},
year = {2018},
abstract = {We investigate the effect of the number of arms
(functionality f) on the mobility of the branch point in
symmetric star polymers. For this purpose we carry out
large-scale molecular dynamics simulations of simple
bead–spring stars and neutron spin echo (NSE) spectroscopy
experiments on center labeled polyethylene stars. This
labeling scheme unique to neutron scattering allows us to
directly observe the branch point motion on the molecular
scale by measuring the dynamic structure factor. We
investigate the cases of different functionalities f = 3, 4,
and 5 for different arm lengths. The analysis of the branch
point fluctuations reveals a stronger localization with
increasing functionality, following 2/f scaling. The dynamic
structure factors of the branch point are analyzed in terms
of a modified version, incorporating dynamic tube dilution
(DTD), of the Vilgis–Boué model for cross-linked networks
[ J. Polym. Sci., Part B 1988, 26, 2291−2302]. In DTD the
tube parameters are renormalized with the tube survival
probability φ(t). As directly measured by the simulations,
φ(t) is independent of f, and therefore the theory predicts
no f dependence of the relaxation of the branch point. The
theory provides a good description of the NSE data and
simulations for intermediate times. However, the
simulations, which have access to much longer time scales,
reveal the breakdown of the DTD prediction since increasing
the functionality actually leads to a slower relaxation of
the branch point.},
cin = {JCNS-FRM-II / Neutronenstreuung ; JCNS-1 / JCNS-2},
ddc = {540},
cid = {I:(DE-Juel1)JCNS-FRM-II-20110218 /
I:(DE-Juel1)JCNS-1-20110106 / I:(DE-Juel1)JCNS-2-20110106},
pnm = {6G15 - FRM II / MLZ (POF3-6G15) / 6G4 - Jülich Centre for
Neutron Research (JCNS) (POF3-623) / 6215 - Soft Matter,
Health and Life Sciences (POF3-621)},
pid = {G:(DE-HGF)POF3-6G15 / G:(DE-HGF)POF3-6G4 /
G:(DE-HGF)POF3-6215},
experiment = {EXP:(DE-MLZ)External-20140101},
typ = {PUB:(DE-HGF)16},
UT = {WOS:000419999000025},
doi = {10.1021/acs.macromol.7b01579},
url = {https://juser.fz-juelich.de/record/858954},
}