Dense, hydrophobic coatings comprising hydrophilic nanoparticles are deposited rapidly from water/toluene emulsions. The process of deposition is driven by a Subtle interplay between interfacial phenomena, electrostatic interparticle repulsions. and hydrogen bonding between the NPs and the substrate(s). The packing fractions and the plasmonic properties of the coatings can be controlled by the pH of the aqueous phase. Once formed, the coatings can be further functionalized without a loss of mechanical integrity.