Determination of light-scattering form factors of latex particle dimers with simultaneous static and dynamic light scattering in an aggregating suspension

Light-scattering form factors and hydrodynamic radii of latex particle dimers were obtained by time-resolved experiments in aggregating suspensions of latex particles with radii of 155 and 290 nm. The method relies on a simultaneous measurement of static and dynamic light scattering at different angles with a fiber-optics-based multiangle instrument in the early stages of the aggregation, where only particle dimers are formed. Combined analysis of such simultaneous experiments allows the determination of absolute coagulation rate constants without reference to light-scattering and hydrodynamic properties of the dimers. The knowledge of this rate constant permits the evaluation of the dimer form factors from the static or the dynamic experiment. The experimentally determined form factors agree well with results of calculation based on modal analysis and discrete dipole approximation.