Three polystyrene-based diblock copolymers are evaluated as dispersants for carbon black particles in n-dodecane. Each diblock copolymer forms polystyrene-core micelles in this solvent as judged by variable temperature 1H NMR spectroscopy, DLS, TEM and SAXS. According to a UV spectroscopy supernatant depletion assay, these diblock copolymer micelles adsorb onto the carbon black particles to form a relatively thick stabilizer layer. Consequently, the effective density of the sterically-stabilized carbon black particles is substantially lower than that of the pristine carbon black particles (1.89 g cm-3 as judged by helium pyconometry). In each case, the effective particle density can be determined by determining the particle velocity in both n-dodecane and d26-n-dodecane via analytical centrifugation. Using this corrected particle density enables the true particle size distributions of these carbon black dispersions to be assessed and the thickness of the steric stabilizer layer can be estimated. It is found that the mean particle diameter of the carbon black is close to its primary grain size of 74 nm (as judged by BET nitrogen adsorption studies), which suggests a relatively high degree of dispersion for this model colloidal substrate.

Effect of block composition on micelle size and steric stabilizer layer thickness: Polystyrene-based diblock copolymers are effective dispersants for carbon black particles in n-dodecane

248th National Meeting (2014)

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