Figure 3
From: Enhanced condensation heat transfer using porous silica inverse opal coatings on copper tubes
Scanning electron microscope (SEM) images of an inverse opal coating at different magnifications. The low magnification SEM images in (a) and (b) show fabrication defects (cracks) that formed when the supporting matrix shrank during drying. The inset in (a) shows a vanishing contact angle for a water droplet deposited on the porous structure. The high magnification images in (c) and (d) show the pores which resulted from dissolution of the sacrificial polystyrene beads (≈ 395 nm diameter). The contact points between the polystyrene beads that was not wetted by the solution during co-assembly created interconnected pores (≈ 215 nm diameter).
