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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 29: Interfaces and Thin Films

CPP 29.3: Vortrag

Mittwoch, 29. März 2023, 10:15–10:30, MER 02

Proteins as stabilizers for foam films: Untangling the different stabilizing effects — •Kevin Gräff, Sebsatian Stock, Luca Mirau, Sabine Bürger, and Regine von Klitzing — Soft Matter at Interfaces, Technische Universität Darmstadt, Darmstadt, Germany

Macroscopic foams consist of foam films, which separate the single air bubbles from each other. Investigation of foam films is crucial to understand macroscopic foam properties such as foam stability. In order to untangle electrostatic, steric and network stabilization effects, we study and compare two globular proteins (β-lactoglobulin and bovine serum albumin) and a disordered, flexible protein (whole casein) at low ionic strengths with varying solution pH. Image intensity measurement allows to record spatially resolved disjoining pressure isotherms in a Thin Film Pressure Balance (TFPB). This reveals insights into the structure formation in inhomogeneous protein films. We introduce inhomogeneity tracking (feature-tracking) as a novel method to enable the measurement of interfacial mobility and stiffness of foam films. Around the isoelectric point, Newton Black Films form which are stable for the globular proteins while they are unstable for the disordered flexible one. This difference in film stability is explained by different characteristics of the network structures which is supported by findings in the bulk and at the surface of the respective protein solutions.

[1] Gräff, K. et al, (2022), Untangling effects of proteins as stabilizers for foam films, Front. Soft. Matter 2:1035377.