Kinetic studies of magnetic latex particles' self-assembly under applied magnetic field

The applied field and concentration dependence of growth of the magnetic latex particles was traced by microscopy and small angle light scattering methods. Magnetic latex particles, diameter 0.8 mu m and ion oxide contents 68%, have been studied at the solution concentration 0.05-0.2 wt% and magnetic field strength 3-24 gauss. When the magnetic field was applied, the particles make the linear alignments and growth-release occurs through reversible processes. The cluster formation is experimentally investigated under the low magnetic field strength where the aggregation is not disrupted by the side-by-side interaction between the linear clusters. The cluster size growth mechanism and the rate of cluster formation was compared by two different techniques, microscope and small angle light scattering (SALS). Good agreement was obtained between the two methods, and (s(t)) = s(0)[1 + (t/tau)(1.0)] was observed during the initial stage of growth, where (s(t)) is a cluster size distribution function, s(0) is the initial size of the particle, t is time, and tau is the characteristic time. Then the clusters are saturated and time dependent increment of the clusters slows down.