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Description
In dilute aqueous solution, diblock copolymers with a hydrophobic and a thermo-responsive block self-assemble into core-shell micelles. Here, we present the self-assembly behavior of the diblock copolymer PMMA-b-PNIPAM consisting of a short hydrophobic poly(methyl methacrylate) and a long thermoresponsive poly(N-isopropylacrylamide) block. Synchrotron small-angle X-ray scattering reveals that, below the cloud point CP, spherical micelles are formed, having a PMMA core and a hydrated PNIPAM shell. Above the CP, the micellar shell dehydrates and contracts, and the micelles form aggregates [1]. Applying pressure to an aqueous micellar solution of PMMA-b-PNIPAM is a tool to alter the hydration behavior of the PNIPAM block [2]. We find that not only the value of the CP, but also the transition behavior depends on pressure [3]. The pressure-induced alteration of the properties of the micellar shell and the correlation between the micelles allows investigating the relation between these effects.
References
[1] Ko, C.-H., Papadakis, C. M. et al. Self-Assembled Micelles from Thermoresponsive Poly(methyl methacrylate)-b-poly(N-isopropylacrylamide) Diblock Copolymers in Aqueous Solution. Macromolecules 2021, 54, 384.
[2] Papadakis, C. M.; Niebuur, B.-J.; Schulte, A. Thermoresponsive Polymers under Pressure with a Focus on Poly(N-isopropylacrylamide) (PNIPAM). Langmuir 2024, 40, 1.
[3] Alvarez Herrera, P. A., Papadakis, C. M. et al. Effect of Pressure on the Micellar Structure of PMMA b PNIPAM Diblock Copolymers in Aqueous Solution. Macromolecules 2024, 57, 10263.
