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@PHDTHESIS{Kyrey:872595,
author = {Kyrey, Tetyana},
title = {{I}nternal structure and dynamics of {PNIPAM} based
microgels in bulk and adsorbed state at different internal
crosslinker distributions},
school = {TU Darmstadt},
type = {Dissertation},
address = {Darmstadt},
publisher = {TU Darmstadt},
reportid = {FZJ-2020-00093},
pages = {135p.},
year = {2019},
note = {Dissertation, TU Darmstadt, 2019},
abstract = {Stimuli-responsive microgels are a unique class of polymer
structures which can undergo a fast response to an external
trigger such as light, temperature or pH. It provides a wide
potential application spectrum in optical devices, smart
surface coatings, emulsion stabilisation etc. The most
prominent example of these microgels are
poly(N-isopropylacrylamide)(PNIPAM) microgels. During the
last decades PNIPAM-based microgels were widely studied and
serve nowadays as model systems for the investigation of the
basic properties of microgels and the principles of
supported transport of active substances, e.g. drug
delivery. The responsive behaviour of the microgels is
governed by the polymer network structure, i.e. the
crosslinking of the polymer chains has a considerable
influence on the physico-chemical and mechanical properties
of the microgels. Especially the amount and the crosslinker
distribution within a single microgel have a high relevance
for the application as well as for the understanding of the
microgel nature. This thesis focuses on a detailed analysis
of microgels in solution and at interfaces with scattering
experiments. Neutron and X-ray scattering provide a unique
insight into the structure and dynamics of microgels,
especially at the interface with grazing incidence small
angle neutron scattering and neutron spin-echo spectroscopy
(GISANS and GINSES). New insights into the inner structure
and dynamics have been gained with improved experimental
conditions and data analysis. This thesis is divided into
the two main parts. In order to characterise the internal
structure and dynamics of the PNIPAM microgels with respect
to the crosslinker (N,N'-methylenebis(acrylamide), BIS)
distribution, sophisticated analysis of the internal
microgel (domain-like) structure and studies of its
influence on the polymer dynamics in nanometer and
nanosecond scales are presented in the first part of the
thesis. In the context of smart polymer coatings, the
influence of the confinement to the solid surface on the
internal architecture and the thermoresponsiveness of the
adsorbed PNIPAM microgels is investigated. It is shown that
in contrast to the atomic force microscopy, the
inhomogeneities of the polymer network of the adsorbed soft
microgels can be achieved with surface sensitive neutron
reflectometry and GISANS. The second part of the thesis aims
at the peculiarities of the scattering experiments of thin
polymer layers under grazing incidence conditions.
Simulation of the scattering signal within the Distorted
Wave Born Approximation is presented in order to improve the
analysis of the GINSES data and to simplify the initial
planing and performance of the grazing incidence
experiments. The main impacts of this thesis are (i) an
extended description of the complex internal structure,
dynamics and the thermoresponsiveness of the PNIPAM microgel
before and after adsorption onto a solid surface and (ii)
demonstration the advantages of the investigation of the
polymer systems at grazing incidence conditions in
combination with numerical simulations.},
cin = {JCNS-FRM-II / MLZ / JCNS-1},
cid = {I:(DE-Juel1)JCNS-FRM-II-20110218 / I:(DE-588b)4597118-3 /
I:(DE-Juel1)JCNS-1-20110106},
pnm = {6G4 - Jülich Centre for Neutron Research (JCNS) (POF3-623)
/ 6G15 - FRM II / MLZ (POF3-6G15)},
pid = {G:(DE-HGF)POF3-6G4 / G:(DE-HGF)POF3-6G15},
experiment = {EXP:(DE-MLZ)KWS1-20140101 / EXP:(DE-MLZ)KWS2-20140101 /
EXP:(DE-MLZ)KWS3-20140101 / EXP:(DE-MLZ)J-NSE-20140101 /
EXP:(DE-MLZ)MARIA-20140101},
typ = {PUB:(DE-HGF)11},
urn = { urn:nbn:de:tuda-tuprints-94781},
urn = {urn:nbn:de:tuda-tuprints-94781},
doi = {10.25534/TUPRINTS-00009478},
url = {https://juser.fz-juelich.de/record/872595},
}