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@ARTICLE{Seibt:859965,
author = {Seibt, Susanne and With, Sebastian and Bernet, Andreas and
Schmidt, Hans-Werner and Förster, Stephan},
title = {{H}ydrogelation {K}inetics {M}easured in a {M}icrofluidic
{D}evice with in {S}itu {X}-ray and {F}luorescence
{D}etection},
journal = {Langmuir},
volume = {34},
number = {19},
issn = {1520-5827},
address = {Washington, DC},
publisher = {ACS Publ.},
reportid = {FZJ-2019-00771},
pages = {5535 - 5544},
year = {2018},
abstract = {Efficient hydrogelators will gel water fast and at low
concentrations. Small molecule gelling agents that assemble
into fibers and fiber networks are particularly effective
hydrogelators. Whereas it is straightforward to determine
their critical concentration for hydrogelation, the kinetics
of hydrogelation is more difficult to study because it is
often very fast, occurring on the subsecond time scale. We
used a 3D focusing microfluidic device combined with
fluorescence microscopy and in situ small-angle X-ray
scattering (SAXS) to study the fast pH-induced gelation of a
model small molecule gelling agent at the millisecond time
scale. The gelator is a 1,3,5-benzene tricarboxamide which
upon acidification assembles into nanofibrils and fibril
networks that show a characteristic photoluminescence. By
adjusting the flow rates, the regime of early nanofibril
formation and gelation could be followed along the
microfluidic reaction channel. The measured fluorescence
intensity profiles were analyzed in terms of a
diffusion–advection–reaction model to determine the
association rate constant, which is in a typical range for
the small molecule self-assembly. Using in situ SAXS, we
could determine the dimensions of the fibers that were
formed during the early self-assembly process. The detailed
structure of the fibers was subsequently determined by
cryotransmission electron microscopy. The study demonstrates
that 3D focusing microfluidic devices are a powerful means
to study the self-assembly on the millisecond time scale,
which is applied to reveal early state of hydrogelation
kinetics. In combination with in situ fluorescence and X-ray
scattering, these experiments provide detailed insights into
the first self-assembly steps and their reaction rates.},
cin = {ICS-1 / Neutronenstreuung ; JCNS-1},
ddc = {540},
cid = {I:(DE-Juel1)ICS-1-20110106 / I:(DE-Juel1)JCNS-1-20110106},
pnm = {551 - Functional Macromolecules and Complexes (POF3-551) /
6G4 - Jülich Centre for Neutron Research (JCNS) (POF3-623)
/ 6215 - Soft Matter, Health and Life Sciences (POF3-621)},
pid = {G:(DE-HGF)POF3-551 / G:(DE-HGF)POF3-6G4 /
G:(DE-HGF)POF3-6215},
typ = {PUB:(DE-HGF)16},
pubmed = {pmid:29583009},
UT = {WOS:000432417700021},
doi = {10.1021/acs.langmuir.8b00384},
url = {https://juser.fz-juelich.de/record/859965},
}