Interaction of Barium Ferrite Particles with Phosphate Ester Dispersants

Using the technique of flow microcalorimetry, both the heat and extent of adsorption of commercially available phosphate ester dispersants on Co and TI doped and undoped barium ferrite particles were measured. To better understand specific chemical interactions between the dispersants and particles, we performed XPS analysis before and after adsorption. Experimental results show distinct differences in the reactivity of doped and undoped particles toward the dispersants. The heats of adsorption of phosphate ester dispersants onto doped ferrite particles were as large as -60 kcal/moie, indicating strong chemical interactions in this system. XPS measurements also show evidence for strong chemical interactions between barium ferrite particles and organophosphate dispersants.