Reversible aggregation Part I. Reversible flocculation monitored by turbidity measurements

The aggregation of four separate polystyrene latices, ranging in diameter from 210 nm to ca. 1 m, using sodium chloride and magnesium sulphate as the electrolytes, has been examined turbidimetrically. The reversibility of the aggregation was examined using a dialysis technique. It was found that for large particle size latices, diameters 781 nm and 1 m, aggregation was reversible in sodium chloride even at concentrations up to 0.5 mol dm^–3. The aggregation of smaller particles was not reversible. The aggregation of large particles in magnesium sulphate solutions was not readily reversed by dialysis. The latter result does not appear to agree with theoretical predictions.Dedicated to Professor Dr. Armin Weiss on the occasion of his 60th birthday.