Minima in Surface-tension and Interfacial-tension Curves

Influence of Surface-Active Trace Impurities on the Surface Properties of Aqueous Solutions of Oligoethylene Glycol Monooctyl Ethers

“…The surface activity parameter a L of C 8 EO 4 is distinctly lower than that of C 8 EO 3 . This means that the former possesses a higher surface activity.…”

“…[2] at lower bulk concentrations (not shown in Fig. 2) and by the equations of Langmuir/Szyszkowski [3,4] at higher concentrations. The transitional interval at intermediate concentrations is described by a polynomial,…”

“…The minima in the equilibrium surface tension ( e ) versus concentration (c) isotherms often observed were already traced back to such impurities long ago (2)(3)(4). An effect on the dynamic surface tension is reported in Ref.…”

“…The majority of these substances have retention times smaller than that of the main component C 8 EO 3 . The original sample was most probably obtained by distillation.…”

Chiral Cyclobutane β-Amino Acid-Based Amphiphiles: Influence of Cis/Trans Stereochemistry on Solution Self-Aggregation and Recognition

“…Because of the small minimum found for cis-1, the sample was purified further by two recrystallizations and using the foam purification method. 34 The minimum could not be reduced even after 24 h foaming, which likely suggests that its origin is not due to the presence of hydrophobic impurities. The break corresponds to the cmc that was determined as the intersection of two fitting straight lines in the plot of γ versus log c. From the slope just before the break, the minimum area per molecule (A m ) was calculated according to the Gibbs adsorption isotherm using 2 as the number of adsorbing species (see the Experimental Section).…”