45567
2016
2016
eng
420
425
6
37
article
Wiley-VCH
Weinheim
1
--
--
--
Quantifying the Interactions in the Aggregation of Thermoresponsive Polymers: The Effect of Cononsolvency
The aggregation kinetics of thermoresponsive core-shell micelles with a poly(N-isopropyl acrylamide) shell in pure water or in mixtures of water with the cosolvents methanol or ethanol at mole fractions of 5% is investigated during a temperature jump across the respective cloud point. Characteristically, these mixtures give rise to cononsolvency behavior. At the cloud point, aggregates are formed, and their growth is followed with time-resolved small-angle neutron scattering. Using the reversible association model, the interaction potential between the aggregates is determined from their growth rate in dependence on the cosolvents. The effect of the cosolvent is attributed to the interaction potential on the structured layer of hydration water around the aggregates. It is surmised that the latter is perturbed by the cosolvent and thus the residual repulsive hydration force between the aggregates is reduced. The larger the molar volume of the cosolvent, the more pronounced is the effect. This framework provides a molecular-level understanding of solvent-mediated effective interactions in polymer solutions and new opportunities for the rational control of self-assembly in complex soft matter systems.
Macromolecular rapid communications
10.1002/marc.201500583
26776153
1022-1336
1521-3927
wos2016:2019
WOS:000372129300003
Papadakis, CM (reprint author), Tech Univ Munich, Lehrstuhl Funktionelle Mat Phys Dept, Fachgebiet Phys Weicher Mat, James Franck Str 1, D-85748 Garching, Germany., papadakis@tum.de
DFG [SPP1259, Pa771/4, Mu1487/8, La611/7]
importub
2020-03-22T19:37:01+00:00
filename=package.tar
1c094d7118dca54f59cf94da99beb9db
Konstantinos Kyriakos
Martine Philipp
Che-Hung Lin
Margarita Dyakonova
Natalya Vishnevetskaya
Isabelle Grillo
Alessio Zaccone
Anna Miasnikova
Andre Laschewsky
Peter Mueller-Buschbaum
Christine M. Papadakis
eng
uncontrolled
colloidal aggregation
eng
uncontrolled
cononsolvency
eng
uncontrolled
interaction potential
eng
uncontrolled
polymer solutions
eng
uncontrolled
self-assembled micelles
eng
uncontrolled
thermoresponsive polymers
Institut für Chemie
Referiert
Import
38477
2015
2015
eng
1891
1896
6
21
36
article
Wiley-VCH
Weinheim
1
--
--
--
Conditional Ultrasound Sensitivity of Poly[(N-isopropylacrylamide)-co-(vinyl imidazole)] Microgels for Controlled Lipase Release
Triggering the release of cargo from a polymer network by ultrasonication as an external, non-invasive stimulus can be an interesting concept for on-demand release. Here, it is shown that, in pH-and thermosensitive microgels, the ultrasound sensitivity of the polymer network depends on the external conditions. Crosslinked poly[(N-isopropylacrylamide)-co-(vinyl imidazole)] microgels showed a volume phase transition temperature (VPTT) of 25-50 degrees C, which increases with decreasing pH. Above the VPTT the polymer chains are collapsed, while below VPTT they are extended. Only in the case of maximum observed swelling, where the polymer chains are expanded, the microgels are mechanically fragmented through ultrasonication. In contrast, when the polymer chains are partially collapsed it is not possible to manipulate the microgels by ultrasound. Additionally, the ultrasound-induced on-demand release of wheat germ lipase from the microgels could be demonstrated successfully. The principle of conditional ultrasound sensitivity is likely to be general and can be used for selection of matrix-cargo combinations.
Macromolecular rapid communications
10.1002/marc.201500311
1022-1336
1521-3927
wos:2015
WOS:000364340800005
Lendlein, A (reprint author), Helmholtz Zentrum Geesthacht, Inst Biomat Sci, Kantstr 55, D-14513 Teltow, Germany., axel.neffe@hzg.de
Deutsche Forschungsgemeinschaft (DFG) [PI 1069/1-1]
Radovan Vukicevic
Axel T. Neffe
Karola Luetzow
Benjamin F. Pierce
Andreas Lendlein
eng
uncontrolled
ultrasound
eng
uncontrolled
polymers
eng
uncontrolled
microgels
eng
uncontrolled
lipase release
eng
uncontrolled
controlled release
eng
uncontrolled
thermoresponsive polymers
eng
uncontrolled
biomaterials
Institut für Chemie
Referiert
36133
2012
2012
eng
254
259
6
3
33
article
Wiley-Blackwell
Malden
1
--
--
--
Kinetics of collapse transition and cluster formation in a thermoresponsive micellar solution of P(S-b-NIPAM-b-S) induced by a temperature jump
Structural changes at the intra- as well as intermicellar level were induced by the LCST-type collapse transition of poly(N-isopropyl acrylamide) in ABA triblock copolymer micelles in water. The distinct process kinetics was followed in situ and in real-time using time-resolved small-angle neutron scattering (SANS), while a micellar solution of a triblock copolymer, consisting of two short deuterated polystyrene endblocks and a long thermoresponsive poly(N-isopropyl acrylamide) middle block, was heated rapidly above its cloud point. A very fast collapse together with a multistep aggregation behavior is observed. The findings of the transition occurring at several size and time levels may have implications for the design and application of such thermoresponsive self-assembled systems.
Macromolecular rapid communications
10.1002/marc.201100631
1022-1336
wos:2011-2013
WOS:000299689600011
Papadakis, CM (reprint author), Tech Univ Munich, Dept Phys, Fachgebiet Phys Weichen Materie, Lehrstuhl Funkt Mat, James Franck Str 1, D-85747 Garching, Germany., papadakis@tum.de
DFG [SPP1259, Pa771/4, Mu1487/8, La611/7]
Joseph Adelsberger
Ezzeldin Metwalli
Alexander Diethert
Isabelle Grillo
Achille Mayelle Bivigou Koumba
André Laschewsky
Peter Müller-Buschbaum
Christine M. Papadakis
eng
uncontrolled
polymer physics
eng
uncontrolled
thermoresponsive polymers
eng
uncontrolled
small-angle neutron scattering
eng
uncontrolled
time-resolved measurements
Institut für Chemie
Referiert