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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 19: Focus: Soft Matter and Nanocomposites - New opportunities with advanced neutron sources II
CPP 19.1: Vortrag
Montag, 16. März 2020, 15:00–15:15, ZEU 222
TOF-NR investigation of cononsolvency in PNIPAM-based block copolymer thin films — •Christina Geiger1, Lucas P. Kreuzer1, Tobias Widmann1, Peixi Wang1, Robert Cubitt2, Cristiane Henschel3, André Laschewsky3, Christine M. Papadakis4, and Peter Müller-Buschbaum1 — 1TU München, Physik-Department, LS Funktionelle Materialien, 85748 Garching, Germany — 2Institut Laue-Langevin, 38042 Grenoble, France — 3Fraunhofer-Institut für Angewandte Polymerforschung, 14476 Potsdam, Germany — 4TU München, Physik-Department, Physik weicher Materie, 85748 Garching, Germany
The diblock copolymer PMMA-b-PNIPAM forms micelles in aqueous solution that exhibit a reversible shell collapse transition at the lower critical solution temperature (LCST). Apart from a temperature stimulus, the collapse can also be induced upon addition of organic cosolvents due to the competitive attachment and detachment of water and cosolvent to the PNIPAM chains. We demonstrate that the cononsolvency effect is transferrable from solutions to thin polymer films. The film swelling and collapse kinetics due to the uptake of water and cosolvent from a saturated vapor atmosphere are investigated with a focus on time-of-flight neutron reflectometry (TOF-NR). Sequential contrasting experiments using protonated and deuterated compounds are performed to differentiate between the distributions of water and cosolvent within the polymer films.