Dynamic aspect of ordering of charged species in solutions - polymer latex particles and linear polymers -

The ordering phenomenon of charged latex particles in solutions was studied by the ultramicroscopic method. The observed interparticle distance (2Dexp) was smaller than the average distance calculated from the latex concentration (2Do) at low concentrations of highly charged latices. Non-space-filling ordering (the two-state structure) was photographed, suggesting the existence of an interparticle attraction. The trajectories of the particles were determined by a movie device. The dynamics of the particles in disordered regions were found to be in an agreement with Einstein's theory on Brownian motion, and the oscillatory motion of the particles in the ordered region was substantially violent. The small angle X-ray study on linear polyions showed a single, broad peak under suitable conditions. The peak position moved with polymer concentration, salt concentration, temperature and molecular weight. Mixing of samples of two different molecular weights gave a new scattering curve, the peak position of which was different from that of the parent peaks. Thus, the peak was concluded to be due to an intermolecular ordering. The Bragg spacing (2Dexp) was found to be smaller than the average distance (2Do), indicating the non-space-filling ordering and hence the intermacroion attraction. The intensity calculation agreed with the observed scattering intensity, when a large distortion of the lattice (much larger than that of the latex crystal) was taken into account. Thus the single, broad peak was rationalized as an indication of distorted intermolecular ordering. Finally, the activity of macroionic species was demonstrated to decrease with increasing concentration with a quite enormous rate, which is consistent with the intermacroion attraction concluded from the microscopic and X-ray studies. Common behaviors of the macroion systems and their model (latex particle) systems were noted for some basic properties.