Well-Characterized Monodisperse Latexes as Model Colloids |
| |
Authors: | J W Vanderhoff H J Van Den Hul |
| |
Institution: | 1. National Printing Ink Research Institute Lehigh University , Bethlehem , Pennsylvania , 18015;2. Central Laboratory Dow Chemical (Nederland) , N.V. , Terneuzen , The Netherlands |
| |
Abstract: | Monodisperse polystyrene latexes prepared with persulfate-ion initiator can be ion exchanged to remove the adsorbed emulsifier and solute electrolyte. Rigorous purification of the ion-exchange'resins is necessary to avoid contamination with leached polyelectrolytes. These ion-exchanged latexes are stabilized with the residual sulfate end-groups of the polymer molecules, the number of which is determined by conductoroetric titration. The result is a dispersion of monodisperse spheres with-a constant and known surface charge due to chemically-bound strong-acid groups. These latexes are ideal models for colloidal studies. Preliminary experiments of stability, adsorption, sedimentation, viscosity, interference colors, and conductance give consistent results, e.g., the particle double-layer interactions determined by viscosity are in accord -with the particle spacings estimated from interference colors, the double-layer parameters estimated from conductometric titration and conductance measurements account for the measured decrease in sedimentation rate due to double-layer interactions, and the molecular area of sodium dodecyl sulfate measured by adsorption in latex is in agreement with literature values. |
| |
Keywords: | |
|
|