Dispersion of Aggregate Particles in Liquid by a Freezing Method

A simple method to disperse aggregate particles suspended in liquid is proposed. The method consists of successive freezing and melting of suspensions. Aggregates consisting of submicron particles were found to be almost completely dispersed into primary particles after about 5 freezing-and-melting cycles, provided that the particle surface could be well wetted with the freezing liquid (dispersion medium). As the dispersion mechanism, it is thought that when the liquid phase is frozen, the expansion or shrinkage of the volume of liquid existing between primary particles causes relative displacement between the particles. This displacement increases the interstice between them resulting in the decrease in adhesion force.