PRODUCTION OF HIGHLY CONCENTRATED NANOPHASE AG DISPERSOIDS WITHOUT AGGREGATION

High-number-density, contact-free nanophase silver particles were prepared in hexane. The particles were produced by an evaporation/condensation aerosol process, trapped in an organic solvent, coated with a surfactant, and then concentrated. A highly concentrated state (10(18)-10(19) particles m-3) could be achieved in hexane for particles with 7 nm mean diameter. The changes in particle size and agglomeration during processing were determined from electron microscopy and photon correlation spectroscopy. The surfactant coating of the particle surface effectively prevented fusion of the nanophase particles. The advantage of this method was confirmed by the size preservation of the particle size distribution after deflocculation from the coagulums which had formed upon concentrating the solution.