Two-component monolayers IV. The excess enthalpies and entropies of mixing in the octadecanol-docosyl sulfate system

Bidimensional mixtures of polymethylmethacrylate with fatty esters at water-air interface

“…All this confirms what was already found for the surface compressibility moduli and for the change in surface area as a function of molar ratios. Figure 7 shows the values of A G~ix at the temperatures of 15, 20, 25 and 30 ~ derived by integration following Goodrich's method (8), up to n = 8 dyn/cm, and the values ofA HMix.E and ofA S~ix., calculated according to Barnes's procedure (9).…”

Mixed Monolayers of Cyclosporin-A and Phospholipids at the Air–Water Interface

“…This value corresponds to a point in the compression curve where the vapor phase coexists with the expanded liquid phase (or condensed liquid phase); that is to say, the point where the pressure begins to rise significantly during compression of the monolayer. With the experimental equipment used, this value can be assumed to be zero, which entails ignoring the possible contribution to G exc of the data obtained at high molecular areas (i.e., at low surface pressures), as previously done by other authors (17)(18)(19)(20).…”

“…As has already been indicated n 1 = x 1 and n 2 = x 2 and if the molar area, σ , is replaced by the molecular area or area per molecule, A, the equation becomes [18] where N is Avogadro's number, A 1 , A 2 , and A 1,2 are the molecular areas of the pure components 1 and 2 and the mixture, respectively, at a given surface pressure π , X 1 and X 2 are the mole fractions of the components in the mixed film, and G exc can be calculated from the area under the π -A curves for the mixtures and pure components. The upper limit of the integral was chosen arbitrarily (we used 5, 10, and 20 mN/m) and π * is the surface pressure at which the monolayer components are assumed to mix in the ideal manner (16).…”

Polyvinylpyridine with polyoctadecylmethacrylate and polyvinylstearate mixtures in monolayers

“…To further confirm these deductions , the values of surface entropy and enthalpy of mixing were calculated, using the same procedure as Bacon anti Barnes [5] and taking for surface entropy the value of 0.026 dyne/cm, which is the temperature coefficient for the water/hexane interface tension. The values thus obtained are shown in figure 3.…”

“…To secure information on the causes of the mutual compatibility, the surface entropy and enthalpy of mixing were taken, as previously done [2], for mixtures of PVP and substances of low molecular weight, using the procedure of K. J. Bacon and G. T. Barnes [5]. These values are shown as a function of mole ratios between moles of monomer unit in figure 3.…”