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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 46: Poster II

CPP 46.13: Poster

Donnerstag, 12. März 2026, 09:30–11:30, P5

Interfacial Dilational Rheology of Microgel Layer at the air-water interface — •Jana Sänger, Atieh Razavi, Regine von Klitzing, and Amin Rahimzadeh — Soft Matter at Interfaces, Institute for condensed Matter Physics, Technical University of Darmstadt, Hochschulstraße 8, 64289 Darmstadt, Germany

Interfacial tension and dilational interfacial rheology of Poly (N-Isoprpylacrylamide) (PNIPAM) microgel layer at air-water interfaces are characterized using pendant-drop techniques. Static interfacial tension was first measured with a drop shape analyser by fitting the droplet profile to the Young-Laplace equation. To probe the interfacial elasticity of microgel dispersions, a Profile Analysis Tensiometer (PAT-1) is employed to impose controlled harmonic oscillations on pendant drops with volumes of 10 μL and microgel concentrations between 0.1 wt% and 0.015 wt%. By using a Fourier transformation, the surface dilational modulus is determined, and the elasticity modulus is then identified as the real part of the surface dilational modulus. In order to remain within the linear range of the interfacial dilational elasticity, various amplitude ratios were systematically tested, and a maximum amplitude ratio of 6% was found. Our study shows that the elastic modulus is frequency-dependent. By increasing the frequency, an increasing elastic modulus is determined. Furthermore, we observe a shift of the maximum elasticity modulus towards the lower surface pressure values by increasing the frequency.

Keywords: Poly (N-Isopropylacrylamide) Microgels; Interfacial Rheology