Study of the Droplet Pinning Force in the Transition from Dry to Liquid-Infused Thin Polymer Films

The change in the pinning force during the transition from dry to oil-impregnated thin polymer films is studied for droplets of water and hexadecane. A careful variation of the oil amount in the films is performed by means of supercritical impregnation. The film thickness dependence on the oil content is measured using ellipsometry and compared to gel swelling theory estimates. Depending on the oil content, two cases of pinning force behavior have been identified. For each case, the factors that determine the pinning force are discussed. The pinning force in the transition from dry to equilibrium swollen gel films is well approximated by the Joanny and de Gennes hysteresis model of dilute defects.

Automated summary

This study investigates the change in pinning force during the transition from dry to oil-impregnated thin polymer films for water droplets and hexadecane droplets. By varying the oil content in films using supercritical impregnation, two cases of pinning force behavior are identified, and the factors that determine the pinning force are discussed. The results show that the pinning force in the transition can be well approximated by the hysteresis model of dilute defects proposed by Joanny and de Gennes.