STABILIZATION OF ALUMINA SUSPENSIONS IN AQUEOUS AND NONAQUEOUS MEDIA BY A HYDROPHOBICALLY-MODIFIED POLYMER

A hydrophobically modified polymer, DAPRAL GE 202, is shown to stabilize alumina both in water and in toluene. The fluorescence technique, utilizing pyrene for the aqueous system and 7-dimethylamino-4-methylcoumarin for the non-aqueous system as probes, was used to investigate the polymer association and orientation in the bulk solution and at the solid-liquid interface. It is proposed that while in the aqueous system the stabilization is caused by both electrostatic repulsion and steric hindrance, the steric hindrance provided by the adsorbed polymer is responsible for the stabilization in toluene.