Contact angle dynamics on pseudo-brushes: Effects of polymer chain length and wetting liquid

International audience; In this study we investigate the exceptional wetting properties of thin polymer layers. Here the polymer is deposited in the form of a polydimethylsiloxane (PDMS) pseudo-brush and contact line dynamics are measured for both varying polymerization index and nature of the partially-wetting liquid. We use a custom-built experimental apparatus to explore wetting dynamics over 7 decades of velocity, with a precision of 0.01 • in variations of the contact angle. We show that the presence of a pseudo-brush can result in a remarkably small contact angle hysteresis as well as the appearance of an additional source of dissipation and that these two phenomena depend on the chain length and the wetting liquid. Qualitatively, we interpret these findings as the ability of the layer to behave as a liquid-like interface, and quantitatively by using a simple model of viscoelastic dissipation in soft thin films.