Dresden 2026 – scientific programme

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 58: Gels, Polymer Networks and Elastomers III

CPP 58.5: Talk

Friday, March 13, 2026, 12:30–12:45, ZEU/0255

Steric Origins of Microgel Thermoresponsiveness Revealed by All-Atom Polymer Simulations — •Jannis Krüger¹, Letizia Tavagnacco², Emanuela Zaccarelli², and Thomas Hellweg¹ — ¹Physical and Biophysical Chemistry, Bielefeld University, Germany — ²Department of Physics, Sapienza University of Rome, Italy

Microgels based on N-isopropylacrylamide (NIPAM) are well established in soft matter science due to their thermoresponsive swelling behavior. Dynamic light scattering (DLS) reveals a sharp decrease in the hydrodynamic radius at a characteristic volume phase transition temperature (VPTT), which occurs around 34^∘C. In our previous work¹ we observed that by adding a non-thermoresponsive comonomer such as N-tert-butylacrylamide (NtBAM), this transition broadens in temperature until it disappears at high molar contents. The VPT is typically interpreted in terms of hydrophilicity or hydrophobicity; however, the steric demand of chemical substituents is often overlooked. In this work, we compare DLS measurements with all-atom molecular dynamics simulations of NIPAM and NtBAM polymer chains in water, to show how subtle differences, like replacing an isopropyl with a tert-butyl group, substantially affects the coil-globule transition of polymers in water, thereby providing deeper insights into the molecular origin of the broadening and lowering of the VPTT in real microgels.

[1] J. Krüger, S. Kakorin, and T. Hellweg, Colloid Polym. Sci. 303, 1815 (2024).

Keywords: Microgels; Molecular Dynamics; Volume Phase Transition; Dynamic light scattering