Membrane osmometry of aqueous micellar systems

Osmotic Pressure of Uncharged and Weakly Charged Oil/Water Microemulsion Droplets

“…[1][2][3][4][5] Together with the molecular weight, calculated from extrapolating Π/c to c ) 0, where c is the concentration, the interparticle interaction may be obtained from the concentration dependence on Π, like the second virial coefficient or the osmotic compressibility. Measurement of osmotic pressure is an inexpensive alternative to direct determination of molecular interaction, like direct force measurements, and is also directly applicable to most systems.…”

“…The polar/apolar interface, separating the pentaethylene oxide from the hydrocarbon chain of the surfactant monolayer, has an essentially invariant area per molecule. Several membrane osmometers are described in the literature, 2,22,23 from quite simple to more sophisticated architecture. The alkyl chains make up approximately half of the surfactant volume.…”

“…Classically, the goal when measuring the osmotic pressure, Π, in colloidal chemistry was to obtain the molecular weight, e.g., for a polymer. Later, measurements of self-associated structures, like surfactant micelles, were also reported. − Together with the molecular weight, calculated from extrapolating Π/ c to c = 0, where c is the concentration, the interparticle interaction may be obtained from the concentration dependence on Π, like the second virial coefficient or the osmotic compressibility. In our case, we have a former knowledge of the solution microstructure and are primarily interested in the interaggregate interaction, like the objectives of several osmotic stress studies. − …”

“…We have therefore chosen membrane osmometry as our experimental tool. Several membrane osmometers are described in the literature, ,, from quite simple to more sophisticated architecture. In our laboratory we have constructed an osmometer that we think is optimal for our system.…”