SPP 2171 Spring Conference: Dynamic Wetting of Flexible, Adaptive, and Switchable Substrates

Nanoscale poly(dimethylsiloxane) (PDMS) layers prepared by grafting the polymer chains on a smooth solid surfaces are typical example for the so called slippery covalently-attached liquid surfaces (SCALS). Such surfaces exhibit very low contact angle hysteresis (CAH) and low friction for sliding water drops [1-2]. These properties are commonly attributed to the liquid-like mobility of the tethered, low glass transition temperature, polymer chains. However, to date there is still no clear, molecular level understanding of the involved physical phenomena. Here, we used fluorescence correlation spectroscopy (FCS) to measure the diffusion coefficients of small fluorescent tracers dispersed in the PDMS layers as probes for the local nanoviscosity. Our results show a clear correlation between the molecular mobility in the polymer layers and their slippery behavior.

1. Gresham, I. J.; Lilley, S. G.; Nelson, A. R. J.; Koynov, K.; Neto, P. C.: Nanostructure Explains the Behavior of Slippery Covalently Attached Liquid Surfaces. Angewandte Chemie International Edition 62 (41), e202308008 (2023)
2. Zhou, X.; Wang, Y.; Li, X.; Sudersan, P.; Amann-Winkel, K.; Koynov, K.; Nagata, Y.; Berger, R.; Butt, H.-J.: Thickness of Nanoscale Poly(Dimethylsiloxane) Layers Determines the Motion of Sliding Water Drops. Advanced Materials 36 (29), 2311470 (2024).