Electro "Dynamic" Interaction in charged Polymer Particle Systems

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We have found a maximum in salt concentration-interparticle distance in colloidal crystal relationship. By ultra-small-angle X-ray scattering, we have investigated in detail the nature of this phenomena and the real origin of the colloidal crystal formation. The results obtained can be surmmarized as follows ;(1) The maximum in the relationship corresponds to solid-liquid phase transiton point.(2) The behavior at liquid phase at high salt condition can be well explaine by classical DLVO theory.(3) At the maximum point, the interparticle distance in colloid crystal is the physically possible maximum distance. Hence, at lower salt condition than maximum point, an anomalous overlap of counterion cloud occurs.(4) This anomalous overlap generates an attractive force between paticles, which results in colloidal crystal formation.(5) This attractive interaction is strong when the counterions are protons. When sodium or pottasium ions are counterions, the attractive force is weaker. This clealy means that the motion of the counterions is an important factor for particle interaction.(6) In the mixed dispersions of latex particles which is different in size and/or charge number, a colloidal alloy structure can be formed at certain condition. The structure of colloidal alloy can be well studied by ultra-small-angle neutron scattering. This kind of new structure will be applied to develop a novel functinal materials.