Thursday, November 11, 2010: 10:30 AM
Topaz Room (Hilton)
A method for measuring the pair interaction potential between colloidal particles by extrapolation measurement of collective structure to inﬁnite dilution is presented and explored using simulation and experiment. The method is particularly well suited to systems in which the colloid is ﬂuorescent and refractive index matched with the solvent. The method involves characterizing the potential of mean force between colloidal particles in suspension by measurement of the radial distribution function using 3D direct visualization. The potentials of mean force are extrapolated to inﬁnite dilution to yield an estimate of the pair interaction potential, U(r). We use Monte Carlo (MC) simulation to test and establish our methodology as well as to explore the eﬀects of polydispersity on the accuracy. To further test the method, we use poly-12-hydroxystearic acid-stabilized poly(methyl methacrylate) (PHSA-PMMA) particles dispersed in the solvent dioctyl phthalate (DOP) to test the method and assess its accuracy for three diﬀerent repulsive systems for which the range has been manipulated by addition of electrolyte.