Lower critical solution definition

In recent years, a number of systems have been examined that also exhibit a lower critical solution temperature (LCST), as shown at the top of Figure 7.1. Here, a more unusual thermodynamic property is exhibited when the polymer phase separates from the solvent after being heated. (One might question the nomenclature the puts die LCST above the UCST, but that is the accepted definition.) LCSTs are more difficult to observe experimentally because they often lie well above the normal boiling points of the solvents. 

It has been proposed to define a reduced temperature Tr for a solution of a single electrolyte as the ratio of kgT to the work required to separate a contact +- ion pair, and the reduced density pr as the fraction of the space occupied by the ions. (M+ ) The principal feature on the Tr,pr corresponding states diagram is a coexistence curve for two phases, with an upper critical point as for the liquid-vapor equilibrium of a simple fluid, but with a markedly lower reduced temperature at the critical point than for a simple fluid (with the corresponding definition of the reduced temperature, i.e. the ratio of kjjT to the work required to separate a van der Waals pair.) In the case of a plasma, an ionic fluid without a solvent, the coexistence curve is for the liquid-vapor equilibrium, while for solutions it corresponds to two solution phases of different concentrations in equilibrium. Some non-aqueous solutions are known which do unmix to form two liquid phases of slightly different concentrations. While no examples in aqueous solution are known, the corresponding... 

Temperature dependence of the critical concentration Ce of a foam bilayer formation. The Cc concentration (see Eq. (3.129)) of formation of DMPC foam bilayer was determined on the basis of observations of the final state which the foam film reached during its drainage (see Section 3.2), i.e. either rupture at a definite critical thickness without formation of black spots occurs, or formation of foam bilayer via black spots is observed. Rupture at critical thickness occurred at lower DMPC concentrations in the solution (C < Cc) and black spots were formed at higher concentrations (C > Cc). These black spots encountered the film turning it into a foam bilayer of constant radius. At each temperature a series of observations were carried out at various DMPC concentrations for the determination of Cc (the minimum DMPC concentration at which a foam bilayer is formed). This concentration is... 

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