Transition from Steric to Electrostatically Stabilized Carbon Black Suspensions in Nonpolar Solvents

Stabilization of suspensions in nonpolar media by charge transfer and generation of long range electric double layer interactions has been proposed. The development of stabilizers and dispersants for particle suspensions in nonpolar solvents often involves the characterization of large composition space given a lack of understanding of the details of the stabilizing mechanism.   Using microfluidic and millifluidic approaches to quantify the timescales and lengthscales of sedimentation and stabilization in nonpolar solvents, we have characterized the transition from steric to electrostatic stabilization in a well-studied system; carbon black stabilized with polyalkyl succinic acid. A shift in the concentration of stabilizer needed to achieve long term stability is observed with change in solvent.   To connect this shift to mechanism, the impact of solvent on micelle formation, adsorption to the particle interface and sedimentation has been quantified. Results allow us to investigate the proposed stabilization mechanism by varying composition and solvent.