The isoelectric state at the solution/air interface — effect on the stability of foams and foam films from nonionic surfactants

Correlation between film properties and the purity of surfactants

“…The present study provides further evidence for the general phenomenon that surfaces of foam films stabilized by nonionic surfactants are charged. 1,6,[8][9][10]12,13,15,32,33 In the present work, the surface potentials are found to be c 0 ¼ 40 and 38 mV for c ¼ 2.5 Â 10 À4 and 5.0 Â 10 À4 M, respectively, which correspond to surface charge densities of q 0 ¼ 1.01 and 0.95 mC m À2 . The DLVO calculations are presented as solid lines in Fig.…”

“…They found that h eq decreases with increasing c El until a NBF is formed at c El ¼ 5 Â 10 À4 M. In a concentration range from 5 Â 10 À4 to 3 Â 10 À3 M the formation of either a CBF or a NBF is observed until at c El > 3 Â 10 À3 M a NBF is directly formed. Khristov et al 13 also investigated the equilibrium film thickness of C 10 E 4 solutions. In this study, a concentration of 8 Â 10 À5 M was chosen and h eq was monitored as a function of pH.…”

“…The recent publication of studies dealing with this topic illustrates the resurgent interest in the P(h)-curves of non-ionic surfactants. The most extensive studies were performed with the sugar surfactants octyl-glycoside (C 8 G 1 ), [6][7][8] n-decyl-b-Dmaltoside (b-C 10 G 2 ) 9 and n-dodecyl-b-D-maltoside (b-C 12 G 2 ), 10 as well as with the alkyl polyglycol ethers C 12 E 11 , 11 C 10 E 4 , [12][13][14][15] C 10 E 2 , 14 C 10 E 8 , 14,15 C 12 E 4 , 14,15 and eicosaoxyethylene-nonylphenolether (NP20). [11][12][13] For the sake of completeness we would like to mention that a lot of work has been done with respect to the equilibrium film thickness h eq , i.e.…”

Investigations on foamability of surface-chemically pure aqueous solutions of functionalized alkylaldonamides

“…This everincreasing interest in the foam systems has evoked many scientific (theoretical and experimental) efforts to describe the foam behavior and to find the principles and mechanisms governing the foam formation [7][8][9]. However, a foam represents a very complicated system that is dependent on various kinds of physicochemical processes and properties, namely, on the method of the foam generation, the gas transport through lamellae, the mechanical deformation of lamellae, the interlamellar drainage, the disjoining pressure within thin liquid films, the adsorption kinetics, the surface rheological parameters (dilatational elasticity and viscosity), the presence of an electrochemical double layer, etc.…”

Hydrosolubilization of Large Aromatic Molecules: Facile Synthesis and Characterization of Water-Soluble Derivatives of Decacyclene

“…Water solubilization of aromatic hydrocarbons is a goal of aimed interest to achieve amphiphilic materials which can display several important properties in different ambits that range from metabolic biochemistry [1] to catalysis, [2][3][4] not to mention their potential chemical and physical roles as matters and precursors for surfactants, [5,6] foaming agents, [7,8] molecular carriers, [9][10][11] polyelectrolyte networks-based materials, [12] water soluble fluorescence markers, [13][14][15] pigments or inks. [16,17] Within this perspective, it is a challenge of importance the performing of efficient strategies of synthesis focused on largely available, nontoxic cheap organic frameworks that can be carried out in actual mild conditions.…”