OBVIOUS AND NONOBVIOUS INFLUENCES OF SURFACTANTS ON THE FORMATION OF NANOSIZED PARTICLES

Precipitation of beta-FeOOH in the presence of aggregated surfactant d omains shows expected influences on particle size and distribution. Th e crystal structure of the product is similar to that found in homogen eous aqueous solution. Surfactant stabilization of the nanoparticles i n dispersion is observed over several months in lamellar liquid crysta l media. An important and unexpected observation is seen upon incubati on of the precipitated material in the presence of excess surfactant. Particle size reduces and the size distribution becomes more narrow as the time of contact with the medium is increased.