OBSERVATION OF THE DYNAMIC COLLOIDAL INTERACTION FORCES BETWEEN CASEIN-COATED LATEX-PARTICLES

We describe a refined version of the particle scattering apparatus due to van de Ven (Langmuir 1994, 10, 3046) for measuring the dynamic int eractions between colloidal particles in a flow field. Polystyrene lat ex particles (diameter 5.1 mu m) were studied, stabilized by beta-case in and alpha(s1)-casein, at pH 7 and ionic strengths of 0.1 and 0.01 m ol dm(-3). The beta-casein system exhibited stronger interparticle rep ulsion and less tendency for particle flocculation at the lower ionic strength. At ionic strength 0.1 mol dm-3 the alpha(s1)-casein system e xhibited stronger interparticle repulsion than the beta-casein system. This behavior is consistent with other measurements on the properties of casein-coated particles.