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@ARTICLE{DeFrancesco:865347,
author = {De Francesco, Alessio and Scaccia, Luisa and Lennox, R.
Bruce and Guarini, Eleonora and Bafile, Ubaldo and Falus,
Peter and Maccarini, Marco},
title = {{M}odel-free description of polymer-coated gold
nanoparticle dynamics in aqueous solutions obtained by
{B}ayesian analysis of neutron spin echo data},
journal = {Physical review / E},
volume = {99},
number = {5},
issn = {2470-0045},
address = {Woodbury, NY},
publisher = {Inst.},
reportid = {FZJ-2019-04845},
pages = {052504},
year = {2019},
abstract = {We present a neutron spin echo study of the nanosecond
dynamics of polyethylene glycol (PEG) functionalized
nanosized gold particles dissolved in D2O at two
temperatures and two different PEG molecular weights (400D
and 2000D). The analysis of the neutron spin echo data was
performed by applying a Bayesian approach to the description
of time correlation function decays in terms of exponential
terms, recently proved to be theoretically rigorous. This
approach, which addresses in a direct way the fundamental
issue of model choice in any dynamical analysis, provides
here a guide to the most statistically supported way to
follow the decay of the intermediate scattering functions
I(Q,t) by basing on statistical grounds the choice of the
number of terms required for the description of the
nanosecond dynamics of the studied systems. Then, the
presented analysis avoids from the start resorting to a
preselected framework and can be considered as model free.
By comparing the results of PEG-coated nanoparticles with
those obtained in PEG2000 solutions, we were able to
disentangle the translational diffusion of the nanoparticles
from the internal dynamics of the polymer grafted to them,
and to show that the polymer corona relaxation follows a
pure exponential decay in agreement with the behavior
predicted by coarse grained molecular dynamics simulations
and theoretical models. This methodology has one further
advantage: in the presence of a complex dynamical scenario,
I(Q,t) is often described in terms of the
Kohlrausch-Williams-Watts function that can implicitly
represent a distribution of relaxation times. By choosing to
describe the I(Q,t) as a sum of exponential functions and
with the support of the Bayesian approach, we can explicitly
determine when a finer-structure analysis of the dynamical
complexity of the system exists according to the available
data without the risk of overparametrization. The approach
presented here is an effective tool that can be used in
general to provide an unbiased interpretation of neutron
spin echo data or whenever spectroscopy techniques yield
time relaxation data curves.},
cin = {MLZ / JCNS-FRM-II},
ddc = {530},
cid = {I:(DE-588b)4597118-3 / I:(DE-Juel1)JCNS-FRM-II-20110218},
pnm = {6215 - Soft Matter, Health and Life Sciences (POF3-621) /
6G15 - FRM II / MLZ (POF3-6G15) / 6G4 - Jülich Centre for
Neutron Research (JCNS) (POF3-623)},
pid = {G:(DE-HGF)POF3-6215 / G:(DE-HGF)POF3-6G15 /
G:(DE-HGF)POF3-6G4},
experiment = {EXP:(DE-MLZ)J-NSE-20140101},
typ = {PUB:(DE-HGF)16},
pubmed = {pmid:31212567},
UT = {WOS:000467737500010},
doi = {10.1103/PhysRevE.99.052504},
url = {https://juser.fz-juelich.de/record/865347},
}