TY  - GEN
A1  - Troll, K.
A1  - Kulkarni, Amit
A1  - Wang, W.
A1  - Darko, C.
A1  - Koumba, A. M. Bivigou
A1  - Laschewsky, André
A1  - Müller-Buschbaum, Peter
A1  - Papadakis, Christine M.
T1  - The collapse transition of poly(styrene-b-(N-isopropyl acrylamide)) diblock copolymers in aqueous solution and in thin films
T2  - Colloid and polymer science : official journal of the Kolloid-Gesellschaft
Y1  - 2011
U6  - https://doi.org/10.1007/s00396-010-2344-1
SN  - 0303-402X
VL  - 289
IS  - 2
SP  - 227
EP  - 227
PB  - Springer
CY  - New York
ER  - 
TY  - JOUR
A1  - Adelsberger, Joseph
A1  - Meier-Koll, Andreas
A1  - Bivigou Koumba, Achille Mayelle
A1  - Busch, Peter
A1  - Holderer, Olaf
A1  - Hellweg, Thomas
A1  - Laschewsky, André
A1  - Müller-Buschbaum, Peter
A1  - Papadakis, Christine M.
T1  - The collapse transition and the segmental dynamics in concentrated micellar solutions of P(S-b-NIPAM) diblock copolymers
JF  - Colloid and polymer science : official journal of the Kolloid-Gesellschaft
N2  - We investigate concentrated solutions of poly(styrene-b-N-isopropyl acrylamide) (P(S-b-NIPAM)) diblock copolymers in deuterated water (D2O). Both structural changes and the changes of the segmental dynamics occurring upon heating through the lower critical solution temperature (LCST) of PNIPAM are studied using small-angle neutron scattering and neutron spin-echo spectroscopy. The collapse of the micellar shell and the cluster formation of collapsed micelles at the LCST as well as an increase of the segmental diffusion coefficient after crossing the LCST are detected. Comparing to our recent results on a triblock copolymer P(S-b-NIPAM-b-S) [25], we observe that the collapse transition of P(S-b-NIPAM) is more complex and that the PNIPAM segmental dynamics are faster than in P(S-b-NIPAM-b-S).
KW  - Block copolymers
KW  - Responsive polymers
KW  - Small-angle neutron scattering
KW  - Neutron spin-echo spectroscopy
Y1  - 2011
U6  - https://doi.org/10.1007/s00396-011-2382-3
SN  - 0303-402X
VL  - 289
IS  - 5-6
SP  - 711
EP  - 720
PB  - Springer
CY  - New York
ER  - 
TY  - JOUR
A1  - Zhong, Qi
A1  - Wang, Weinan
A1  - Adelsberger, Joseph
A1  - Golosova, Anastasia
A1  - Koumba, Achille M. Bivigou
A1  - Laschewsky, André
A1  - Funari, Sergio S.
A1  - Perlich, Jan
A1  - Roth, Stephan V.
A1  - Papadakis, Christine M.
A1  - Müller-Buschbaum, Peter
T1  - Collapse transition in thin films of poly(methoxydiethylenglycol acrylate)
JF  - Colloid and polymer science : official journal of the Kolloid-Gesellschaft
N2  - The thermal behavior of poly(methoxydiethylenglycol acrylate) (PMDEGA) is studied in thin hydrogel films on solid supports and is compared with the behavior in aqueous solution. The PMDEGA hydrogel film thickness is varied from 2 to 422 nm. Initially, these films are homogenous, as measured with optical microscopy, atomic force microscopy, X-ray reflectivity, and grazing-incidence small-angle X-ray scattering (GISAXS). However, they tend to de-wet when stored under ambient conditions. Along the surface normal, no long-ranged correlations between substrate and film surface are detected with GISAXS, due to the high mobility of the polymer at room temperature. The swelling of the hydrogel films as a function of the water vapor pressure and the temperature are probed for saturated water vapor pressures between 2,380 and 3,170 Pa. While the swelling capability is found to increase with water vapor pressure, swelling in dependence on the temperature revealed a collapse phase transition of a lower critical solution temperature type. The transition temperature decreases from 40.6 A degrees C to 36.6 A degrees C with increasing film thickness, but is independent of the thickness for very thin films below a thickness of 40 nm. The observed transition temperature range compares well with the cloud points observed in dilute (0.1 wt.%) and semi-dilute (5 wt.%) solution which decrease from 45 A degrees C to 39 A degrees C with increasing concentration.
KW  - Hydrogel
KW  - Thin film
KW  - Thermoresponsive
KW  - LCST behavior
KW  - GISAXS
KW  - AFM
Y1  - 2011
U6  - https://doi.org/10.1007/s00396-011-2384-1
SN  - 0303-402X
VL  - 289
IS  - 5-6
SP  - 569
EP  - 581
PB  - Springer
CY  - New York
ER  -