Tunable Structural Color Surfaces with Visually Self-Reporting Wettability

Functional materials with wettability of specific surfaces are important for many areas. Here, a new lubricant-infused elastic inverse opal is presented with tunable and visually “self-reporting” surface wettability. The elastic inverse opal films are used to lock in the infused lubricating fluid and construct slippery surfaces to repel droplets of various liquids. The films are stretchable, and the lubricating fluid can penetrate the pores under stretching, leaving the surface layer free of lubrication; the resultant undulating morphology of the inverse opal scaffold topography can reversibly pin droplets on the fluidic film rather than the solid substrate. This mechanical stimulation process provides an effective means of dynamically tuning the surface wettability and the optical transparency of the inverse opal films. In particular, as the adjustments are accompanied by simultaneous deformation of the periodic macroporous structure, the inverse opal films can self-report on their surface status through visible structural color changes. These features make such slippery structural color materials highly versatile for use in diverse applications.