Investigation of liquid-liquid demixing and aggregate formation in a membrane-forming system by means of pulse-induced critical scattering (PICS)

Phase separation phenomena in the quasi-ternary system cellulose acetate (CA)/dioxane/water, used as a typical system in the preparation of polymeric membranes for ultrafiltration and reverse osmosis applications, were investigated by means of pulse-induced critical scattering (PICS). Both the cloud point curve and spinodal curve were determined for CA concentrations up to 20% (w/w). The influence of maleic acid (used as an additive in order to improve the membrane performance) on the position of the binodal and spinodal curves and the demixing kinetics were investigated

Free energy surfaces from nonequilibrium processes without work measurement

Recent developments in statistical mechanics have allowed the estimation of equilibrium free energies from the statistics of work measurements during processes that drive the system out of equilibrium. Here a different class of processes is considered, wherein the system is prepared and released from a nonequilibrium state, and no external work is involved during its observation. For such ``clamp-and-release'' processes, a simple strategy for the estimation of equilibrium free energies is offered. The method is illustrated with numerical simulations, and analyzed in the context of tethered single-molecule experiments.Comment: 15 pages, 3 figures (1 color); accepted to J. Chem. Phy