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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 24: Responsive and Adaptive Systems I
CPP 24.6: Talk
Wednesday, March 20, 2024, 11:00–11:15, H 0110
Effect of pressure on the micellar structure of PMMA-b-PNIPAM in a water/methanol mixture — •Pablo A. Álvarez Herrera1, Feifei Zheng1, Peiran Zhang1, Julija Reitenbach1, Heinz Amenitsch2, Peter Müller-Buschbaum1, Cristiane Henschel3, André Laschewsky3, and Christine M. Papadakis1 — 1TU Munich, TUM School of Natural Sciences, Garching, Germany — 2Elettra Sincrotrone, Trieste, Italy — 3Universität Potsdam, Institut für Chemie, Potsdam-Golm, Germany
In pure water, amphiphilic block copolymers consisting of a permanently hydrophobic poly(methyl methacrylate) (PMMA) and a thermoresponsive poly(N-isopropyl acrylamide) (PNIPAM) block form core-shell micelles. At atmospheric pressure, the solubility of the micellar shell can be altered by changing the temperature or by adding a water-miscible co-solvent. Here, we study the effect of pressure on the phase behavior and micellar structure of PMMA21-b-PNIPAM283 in a 90:10 v/v D2O/CD3OD mixture in a pressure range between 10 and 250 MPa. Turbidimetry shows that adding methanol to PMMA-b-PNIPAM in D2O shifts the maximum of the coexistence line to a higher pressure and temperature. Small-angle X-ray scattering reveals the temperature- and pressure-dependence of the core size, shell thickness, shell solvation, micellar correlation, and aggregation behavior of PMMA-b-PNIPAM in a water-methanol mixture. We find that adding methanol increases the mobility of the chains forming the micellar core. Also, the degree of solvation and the thickness of the micellar shell feature a maximum at a pressure of around 100 MPa.
Keywords: thermoresponsive; polymer; self-assembly; pressure; cononsolvency