Growth of coatings on nanoparticles by photoinduced chemical vapor deposition

Photoinduced chemical vapor deposition was used to grow organic coatings on NaCl nanoparticles. Aerosolized nanoparticles were mixed with a vapor-phase coating reactant and introduced into a room-temperature, atmospheric-pressure cell, where the mixture was exposed to 172-nm radiation from a Xe-2* excimer lamp. Several coating reactants were investigated; the most successful was methyl methacrylate (MMA). Tandem differential mobility analysis (TDMA) was used to determine coating thicknesses as a function of initial particle size. For NaCl particles ranging from 20 to 60 nm in mobility diameter, the thicknesses ranged from sub-nm to 20 nm depending on MMA flow rate and initial particle size.