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@ARTICLE{Scherzinger:19771,
author = {Scherzinger, C. and Holderer, O. and Richter, D. and
Richtering, W.},
title = {{P}olymer {D}ynamics in responsive microgels: influence of
cononsolvency and microgel architecture},
journal = {Physical Chemistry Chemical Physics},
volume = {14},
issn = {1463-9076},
address = {Cambridge},
publisher = {RSC Publ.},
reportid = {PreJuSER-19771},
pages = {2762-2768},
year = {2012},
note = {This research project has been supported by the European
Commission under the 7th Framework Programme through the Key
Action: Strengthening the European Research Area, Research
Infrastructures. Contract no.: 226507 (NMI3). This work is
based on experiments performed at the Julich Centre for
Neutron Science JCNS, Forschungszentrum Julich, Germany.},
abstract = {The dynamics of polymers on the nm and ns scales inside
responsive microgels was probed by means of Neutron Spin
Echo (NSE) experiments. Four different microgels were
studied: poly(N-isopropylacrylamide) (PNIPAM) and
poly(N,N-diethylacrylamide) (PDEAAM) microgels, a
P(NIPAM-co-DEAAM) copolymer microgel and a core-shell
microgel with a PDEAAM core and a PNIPAM shell. These four
different microgel systems were investigated in a
D(2)O/CD(3)OD solvent mixture with a molar CD(3)OD fraction
of x(MeOD) = 0.2 at 10 °C. The PNIPAM and the
P(NIPAM-co-DEAAM) microgels are in the collapsed state under
these conditions. They behave as solid diffusing objects
with only very small additional contributions from internal
motions. The PDEAAM particle is swollen under these
conditions and mainly Zimm segmental dynamics can be
detected in the intermediate scattering function at high
momentum transfer. A cross-over to a collective diffusive
motion is found for smaller q-values. The shell of the
PDEAAM-core-PNIPAM-shell particle is collapsed, which leads
to a static contribution to S(q,t); the core, however, is
swollen and Zimm segmental dynamics are observed. However,
the contributions of the Zimm segmental dynamics to the
scattering function are smaller as compared to the pure
PDEAAM particle. Interestingly the values of the apparent
solvent viscosities inside the microgels as obtained from
the NSE experiments are higher than for the bulk solvent. In
addition different values were obtained for the PDEAAM
microgel, and the PDEAAM-core of the
PDEAAM-core-PNIPAM-shell particle, respectively. We
attribute the strongly increased viscosity in the PDEAAM
particle to enhanced inhomogeneities, which are induced by
the swelling of the particle. The different viscosity inside
the PDEAAM-core of the PDEAAM-core-PNIPAM-shell microgel
could be due to a confinement effect: the collapsed
PNIPAM-shell restricts the swelling of the PDEAAM-core and
may modify the hydrodynamic interactions in this restricted
environment inside the microgel.},
keywords = {J (WoSType)},
cin = {ICS-1 / JCNS-1 / JCNS (München) ; Jülich Centre for
Neutron Science JCNS (München) ; JCNS-FRM-II},
ddc = {540},
cid = {I:(DE-Juel1)ICS-1-20110106 / I:(DE-Juel1)JCNS-1-20110106 /
I:(DE-Juel1)JCNS-FRM-II-20110218},
pnm = {BioSoft: Makromolekulare Systeme und biologische
Informationsverarbeitung / Großgeräte für die Forschung
mit Photonen, Neutronen und Ionen (PNI)},
pid = {G:(DE-Juel1)FUEK505 / G:(DE-Juel1)FUEK415},
experiment = {EXP:(DE-MLZ)J-NSE-20140101},
shelfmark = {Chemistry, Physical / Physics, Atomic, Molecular $\&$
Chemical},
typ = {PUB:(DE-HGF)16},
pubmed = {pmid:22252036},
UT = {WOS:000299742000026},
doi = {10.1039/c2cp23328b},
url = {https://juser.fz-juelich.de/record/19771},
}