Monodisperse latexes of synthetic resins separate out the ordered structure with irridescence, the disordered structure with milky white and the state of co-existence of two structures under suitable conditions which are characterized for the solid content of latexes and the electrolyte concentration of their aqueous phase.
This phenomena can be explained by Kirkwood-Alder phase transition theory in statistical mechanics.
The phase separation of monodisperse latexes can be also detected by the measurement of viscosity. Alder theory means that latex particles in the ordered state are constructed the regular array by repulsion and thermal movement.
When purified nonionic surfactant solution was added to the ordered latexes with irridescence, irridescent color was suddenly altered to milky white at a certain point although the surfactant solution had not ionic property.
This phenomena could be guessed that the electrical double layer effect of latexes adsorbed by nonionic surfactant is weakened comparing with that of the non-adsorbed latexes as the dissociation of surface charge of latexes is diminished by the adsorption of nonionic surfactant, therefore, the state of latexes transfered from ordered phase to disordered phase.
In this report, order-disorder phase transition of latexes through the adsorption of nonionic surfactant was studied by the measurement of electric conductivity.
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