TY  - JOUR
A1  - Adelsberger, Joseph
A1  - Bivigou Koumba, Achille Mayelle
A1  - Miasnikova, Anna
A1  - Busch, Peter
A1  - Laschewsky, André
A1  - Müller-Buschbaum, Peter
A1  - Papadakis, Christine M.
T1  - Polystyrene-block-poly (methoxy diethylene glycol acrylate)-block-polystyrene triblock copolymers in aqueous solution-a SANS study of the temperature-induced switching behavior
T2  - Colloid and polymer science : official journal of the Kolloid-Gesellschaft
N2  - A concentrated solution of a symmetric triblock copolymer with a thermoresponsive poly(methoxy diethylene glycol acrylate) (PMDEGA) middle block and short hydrophobic, fully deuterated polystyrene end blocks is investigated in D2O where it undergoes a lower critical solution temperature-type phase transition at ca. 36 A degrees C. Small-angle neutron scattering (SANS) in a wide temperature range (15-50 A degrees C) is used to characterize the size and inner structure of the micelles as well as the correlation between the micelles and the formation of aggregates by the micelles above the cloud point (CP). A model featuring spherical core-shell micelles, which are correlated by a hard-sphere potential or a sticky hard-sphere potential together with a Guinier form factor describing aggregates formed by the micelles above the CP, fits the SANS curves well in the entire temperature range. The thickness of the thermoresponsive micellar PMDEGA shell as well as the hard-sphere radius increase slightly already below the cloud point. Whereas the thickness of the thermoresponsive micellar shell hardly shrinks when heating through the CP and up to 50 A degrees C, the hard-sphere radius decreases within 3.5 K at the CP. The volume fraction decreases already significantly below the CP, which may be at the origin of the previously observed gel-sol transition far below the CP (Miasnikova et al., Langmuir 28: 4479-4490, 2012). Above the CP, small, and at higher temperatures, large aggregates are formed by the micelles.
KW  - Hydrogel
KW  - Thermoresponsive
KW  - LCST behavior
KW  - SANS
Y1  - 2015
UR  - https://publishup.uni-potsdam.de/frontdoor/index/index/docId/38974
SN  - 0303-402X
SN  - 1435-1536
VL  - 293
IS  - 5
SP  - 1515
EP  - 1523
PB  - Springer
CY  - New York
ER  -