Figure 4.

Macro-, micro-, and nanomorphology of network-functionalized silica nanoparticles. (a) Decrease in the effective specific surface area of fluoro-functionalized nanoparticles indicative of a dense networked layer (insets). Gradual decrease from ca. 400 to 100 m²/g. This effect tapers off between 6:1 to 8:1 reaction graft ratios, indicative of surface saturation. (b) Monolayer covalently functionalized nanoparticles without −OH shielding and a covalent–oligomeric network-functionalized nanoparticle with −OH shielding. Water and oil entities are labeled with blue and orange spheres, respectively. Compositions of (purple) straight-chain covalent attachments and (green) oligomeric fluoro-silica networks. F and H atoms are not illustrated for conciseness. Scanning electron microscopy of nanoparticulate surfaces with reaction graft ratios of (c) 1:1, (d) 4:1, (e) 6:1, and (f) 20:1. Morphologies are hierarchical but near-identical, with microglobular features composed of nanospherical particles. (g) Side profile of a coated surface (G6 on glass). Glass substrate contrasted for reference. Additional high-magnification and side-profile geometries are included in Figure S10 for reference.