TY  - JOUR
A1  - Zhong, Qi
A1  - Metwalli, Ezzeldin
A1  - Rawolle, Monika
A1  - Kaune, Gunar
A1  - Bivigou Koumba, Achille Mayelle
A1  - Laschewsky, Andre
A1  - Papadakis, Christine M.
A1  - Cubitt, Robert
A1  - Wang, Jiping
A1  - Mueller-Buschbaum, Peter
T1  - Influence of Hydrophobic Polystyrene Blocks on the Rehydration of Polystyrene-block-poly(methoxy diethylene glycol acrylate)-block-polystyrene Films Investigated by in Situ Neutron Reflectivity
JF  - Macromolecules : a publication of the American Chemical Society
N2  - The rehydration of thermoresponsive polystyrene-block-poly(methoxy diethylene glycol acrylate)-block-polystyrene (PS-b-PMDEGA-b-PS) films forming a lamellar microphase-separated structure is investigated by in situ neutron reflectivity in a D2O vapor atmosphere. The rehydration of collapsed PS-b-PMDEGA-b-PS films is realized by a temperature change from 45 to 23 degrees C and comprises (1) condensation and absorption of D2O, (2) evaporation of D2O, and (3) reswelling of the film due to internal rearrangement. The hydrophobic PS layers hinder the absorption of condensed D2O, and a redistribution of embedded D2O between the hydrophobic PS layers and the hydrophilic PMDEGA layers is observed. In contrast, the rehydration of semiswollen PS-b-PMDEGA-b-PS films (temperature change from 35 to 23 degrees C) shows two prominent differences: A thicker D2O layer condenses on the surface, causing a more enhanced evaporation of D2O. The rehydrated films differ in film thickness and volume fraction of D2O, which is due to the different thermal protocols, although the final temperature is identical.
Y1  - 2016
U6  - https://doi.org/10.1021/acs.macromol.5b02279
SN  - 0024-9297
SN  - 1520-5835
VL  - 49
SP  - 317
EP  - 326
PB  - American Chemical Society
CY  - Washington
ER  - 
TY  - JOUR
A1  - Kyriakos, Konstantinos
A1  - Philipp, Martine
A1  - Lin, Che-Hung
A1  - Dyakonova, Margarita
A1  - Vishnevetskaya, Natalya
A1  - Grillo, Isabelle
A1  - Zaccone, Alessio
A1  - Miasnikova, Anna
A1  - Laschewsky, Andre
A1  - Mueller-Buschbaum, Peter
A1  - Papadakis, Christine M.
T1  - Quantifying the Interactions in the Aggregation of Thermoresponsive Polymers: The Effect of Cononsolvency
JF  - Macromolecular rapid communications
N2  - 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.
KW  - colloidal aggregation
KW  - cononsolvency
KW  - interaction potential
KW  - polymer solutions
KW  - self-assembled micelles
KW  - thermoresponsive polymers
Y1  - 2016
U6  - https://doi.org/10.1002/marc.201500583
SN  - 1022-1336
SN  - 1521-3927
VL  - 37
SP  - 420
EP  - 425
PB  - Wiley-VCH
CY  - Weinheim
ER  -