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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 44: Focus Session: Soft Matter and Nanocomposites: New Opportunities with Advanced Neutron Sources 2
CPP 44.3: Vortrag
Freitag, 9. September 2022, 10:15–10:30, H38
Pathways of micellar collapse and swelling of PMMA-b-PNIPAM in aqueous solution after a rapid change of pressure — •Pablo A. Alvarez Herrera1, Johannes Allwang1, Feifei Zheng1, Cristiane Henschel2, Leonardo Chiappisi3, Alfons Schulte4, André Laschewsky2, and Christine M. Papadakis1 — 1TU München, Physik-Department, Garching, Germany — 2Institut für Chemie, Potsdam-Golm, Germany — 3Institut Laue- Langevin, Grenoble, France — 4University of Central Florida, Orlando, USA
In aqueous solution, diblock copolymers consisting of a permanently hydrophobic and a thermo-responsive block can self-assemble into different morphologies. In particular, poly (methyl methacrylate)- b-poly(N-isopropylacrylamide) (PMMA-b-PNIPAM) forms spherical micelles featuring a PMMA core and a thermo-responsive PNIPAM shell. At atmospheric pressure, the micellar shell dehydrates, and the collapsed micelles form aggregates when heating above the cloud point of PNIPAM [1]. This phase transition can be also induced by changing the pressure. In this contribution, we study the micellar collapse and their posterior aggregation by kinetic small-angle neutron scattering (SANS) in combination with rapid pressure jumps across the co-existence line. The disintegration of the aggregates and the micellar swelling are also investigated by performing the pressure jump in the opposite direction.
[1] C.-H. Ko, C. M. Papadakis et al., Macromolecules 54, 384 (2021).