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@ARTICLE{PuigRigall:844926,
author = {Puig-Rigall, Joan and Obregon-Gomez, Ines and
Monreal-Pérez, Pablo and Radulescu, Aurel and
Blanco-Prieto, María J. and Dreiss, Cécile A. and
González-Gaitano, Gustavo},
title = {{P}hase behaviour, micellar structure and linear rheology
of tetrablock copolymer {T}etronic 908},
journal = {Journal of colloid and interface science},
volume = {524},
issn = {0021-9797},
address = {Amsterdam [u.a.]},
publisher = {Elsevier},
reportid = {FZJ-2018-02268},
pages = {42 - 51},
year = {2018},
abstract = {Tetronics are X-shaped block-copolymers of polyethylene
oxide and polypropylene oxide, which self-assemble into
micelles and can undergo a sol-gel transition; these
transitions are dependent on temperature, concentration but
also pH, due to the central diamine group of the tetrablock.
We report the nanoscale morphologies underlying these
different phases and the rheology of the systems for a very
large, highly hydrophilic block copolymer, Tetronic 908,
through the combined use of oscillatory rheology,
steadyblock-state and time-resolved fluorescence,
small-angle neutron scattering (SANS), dynamic light
scattering (DLS) and Fourier transform infrared attenuated
total reflectance (FTIR-ATR). At low concentrations, SANS
reveal core-shell micelles of ca. 10 nm radius, presenting
a dehydrated core and a highly hydrated shell, with
relatively small aggregation numbers (Nagg ≈ 13). The
micelles are notably affected by the pH, due to the
protonation of the central amine spacer at low pH (pH ≈
2), which shifts micellization to higher temperature, with
smaller micelles than at natural pH. In the intermediate
concentration regime $(10–15\%),$ micelles become smaller
(Nagg ≈ 5), and present a higher hydration of the core. In
the high concentration regime, Tetronic 908 undergoes a
sol-gel transition above a threshold temperature, which is
fully inhibited at acidic pH. SANS data from the gel phase
reveal a BCC order of tightly packed spheres. Temperature
sweeps in oscillatory rheology show a shift of the onset of
gelation towards lower temperatures as concentration
increases, an increase in the elastic modulus G′ and an
expansion of gel region over a larger range of temperatures.
SANS and rheology reveal that at pH below the natural pH
(ca. 8), gelation is shifted to higher temperatures, but the
morphology of the gels is similar, while under highly acidic
conditions the gelation is fully suppresed.},
cin = {JCNS (München) ; Jülich Centre for Neutron Science JCNS
(München) ; JCNS-FRM-II / Neutronenstreuung ; JCNS-1},
ddc = {540},
cid = {I:(DE-Juel1)JCNS-FRM-II-20110218 /
I:(DE-Juel1)JCNS-1-20110106},
pnm = {6G15 - FRM II / MLZ (POF3-6G15) / 6G4 - Jülich Centre for
Neutron Research (JCNS) (POF3-623)},
pid = {G:(DE-HGF)POF3-6G15 / G:(DE-HGF)POF3-6G4},
experiment = {EXP:(DE-MLZ)KWS2-20140101},
typ = {PUB:(DE-HGF)16},
pubmed = {pmid:29631218},
UT = {WOS:000434494400006},
doi = {10.1016/j.jcis.2018.03.096},
url = {https://juser.fz-juelich.de/record/844926},
}