Wetting of Inclined Nano-textured Surfaces by Self-healing Agents

Experiments were conducted to study spreading of droplets of liquid healing agents on tilted nanofiber mats, which is relevant in the framework of self-healing engineered materials with vascular networks. In the present situation the effect of gravity on drop spreading is important, as well as the inclination angle and the mat thickness. In the control case of gravity-driven spreading of droplets on an inclined polydimethylsiloxane (PDMS) surface the results agreed fairly well with the theoretical predictions in the framework of the lubrication theory for the intact surfaces. However, spreading on the inclined nanofiber mats revealed significant deviations from the theory due to the imbibition of liquid into the inter-fiber pores. The imbibition effect, which stems from the wettability-driven suction, increased as the mat thickness increased. Notably, the imbibition effect also increased as the inclination angle increased.