(162e) Characterization of Liquid Nanoparticle Dispersions by Multisample Analytical Centrifugation - Particle Interaction - Colloidal Crystallization

Reducing particle dimensions to nanoscale leads to qualitatively new properties. This holds also for liquid dispersions, which are the most often used form of application of nanoparticles. For characterization of nanoparticle dispersions techniques are preferable, which avoid dilution, thus don't modify dispersion properties. To this end multisample analytical centrifugation proved as an efficient tool. The new multisample approach uses the STEP-technology. Space and time resolved extinction profiles quantify the alteration of particle concentration but also packing behaviour and phase separation during centrifugation. Examples are presented for the detection of the presence of weak flocculation in nanoparticle suspensions, for examination of microgels and colloidal crystallization. The behaviour of microgels was characterized as function of centrifugal acceleration, temperature and concentration. Further, the effect of initial volume concentration and sediment pressure on the speed and extend of the crystallization process was studied.