Determination of Hansen parameters for particles: A standardized routine based on analytical centrifugation

Abstract The Hansen Solubility Parameters (HSP) are powerful descriptors to evaluate interactions of (polymer) molecules and their solubility in different liquids. Although approaches do exist to transfer the HSP-concept to the question of dispersibility of particles, HSP determination of slowly sedimenting (nano)particles (NPs) is time consuming and depends on the subjective evaluation of the experimenter. Herein, we introduce a new method for HSP determination for colloidal systems using analytical centrifugation (AC) which was applied to standardize and accelerate the experimental procedure. However, as not dissolution but dispersion is in focus, we propose to use the term Hansen Dispersibility Parameters (HDP) instead of HSP whenever dispersibility and stability of particles against agglomeration/flocculation are to be discussed. First, we implemented a standard dispersion routine for the well-known, industrially highly relevant pigment carbon black (CB). Then, a standardized method for the evaluation of measured AC profiles and appropriate ranking of NPs dispersibility in different media was developed. We demonstrate outstanding reproducibility of our results by comparing HDP derived for the same CB material from independent experiments performed at two different affiliations. Finally, we show the predictive power of HDP and the accuracy of our approach by evaluating the dispersibility of CB in additional liquids and mixtures of so-called “good” and “poor” liquid media crossing the border from stable to unstable medium conditions. Our study evidences the enormous potential of AC to determine the HDP of colloidal systems using a standardized and non-subjective method to access particle interactions and colloidal stability.