COLLOIDAL AND ELECTROKINETIC BEHAVIOR OF POLY(METHYL METHACRYLATE-CO-BUTYL ACRYLATE) LATEX-PARTICLES

Poly(methyl methacrylate-co-butyl acrylate) latex particles were synth esized by both seeded and unseeded semicontinuous emulsion copolymeriz ation processes. Particle size and surface charge densities were chara cterized by TEM and potentiometric and conductimetric titrations, resp ectively. The electrophoretic mobilities of the latexes were studied a t different ionic strength and constant pH and then at constant ionic strength and different pH. An investigation of the effect of surface d ensity on xi-potential is described. Conversion of mobility values int o xi potentials was accomplished according to the theory of Dukhin-Sem enikhin in order to take anomalous surface conductance into account. T he dimensionless relaxation factor (Rel) was calculated for the differ ent surface charge density of the latexes obtained. The colloidal stab ility of the latex particles after addition of KBr at an appropriate c oncentration was followed monitoring the optical absorbance changes of the dispersion. The critical coagulation concentration (CCC) was obta ined from the intersection points of the straight log W-log C line wit h the chi-axis (stability factor vs. concentration). The stability fac tors of the synthesized latexes were measured at pH 5, 7 and 9. The re sults indicate that these latexes are electrostatically stabilized. (C ) 1997 Elsevier Science Ltd.