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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 4: Interfaces and Thin Films

CPP 4.9: Talk

Monday, March 18, 2024, 11:45–12:00, H 0111

Neutron Reflectivity of Superspreading and Non-Superspreading Trisiloxane Surfactants — •Joshua Reed¹, Séforah Carolina Marques Silva^1,2, Joachim Venzmer², Tatiana Gambaryan-Roisman¹, and Emanuel Schneck¹ — ¹TU Darmstadt, Darmstadt, Germany — ²Evonik Operations GmbH, Essen, Germany

Some trisiloxane surfactants have the remarkable property of being able to superspread: Small volumes of water rapidly wet large areas of hydrophobic surfaces. The molecular properties which govern this technologically relevant effect are still under debate. To gain a deeper understanding, the surfactant behaviour during the spreading process needs to be studied at molecular length scales. Here, we present neutron reflectivity analyses of two trisiloxane surfactants of similar structure, of which only one exhibits superspreading properties. We present an approach to determining the composition of the adsorbed surfactant layer in droplets at the solid-liquid and at the liquid-air interface, and accounting for neutron attenuation of back-reflections in thin layers. Subtle differences between superspreading and non-superspreading surfactants in the volume fractions of the self-consistent analysis might be able to explain the difference in spreading behaviour.

Keywords: Thin Films; Solid/liquid interface; Air/water interface,