Surface Properties Of Aqueous Solutions Research Articles

Micellisation and gelation of triblock copolymer of ethylene oxide and ε-caprolactone, CLnEmCLn, in aqueous solution

Three triblock copolymers of ethylene oxide and Iµ-caprolactone, nominally CL2E90CL2, CL4E90CL4 and CL6E90CL6 have been prepared and characterised. The micellar and surface properties in aqueous solution of the copolymers with CL-block lengths of four and six were investigated as a function of temperature and concentration using surface tension and static and dynamic light scattering techniques. Reversible gelation on cooling solutions of CL6E90CL6 was observed at critical concentrations and temperatures ranging from 130 g kg–1 at 25 °C to 300 g kg–1, at 80 °C.

Effect of double bond on the surface properties of aqueous solutions of eicosapolyenoic acids

Surface tensions of aqueous solution of eicosapolyenoic acids (EA) with 2∼5 double bonds were measured by use of a Du Nöuy tensiometer at pH 7.80 and 25°C, and the effects of double bond on the surface properties of EA were investigated. The value of critical micelle concentration of EA increased twofold with increasing number of double bonds. The free energy for the adsorption per double bond at the air-water interface was estimated as 2.47 kJ (double bond)−1, and the negative value of free energy for the adsorption of EA molecule decreased with increasing number of double bonds.

Physical and surface properties of aqueous solutions of polyvinyl alcohols having an n‐alkylthio end group

AbstractThe polyvinyl alcohols (PVAs) having a n‐alkylthio end group of 10 through 16 carbon atoms were found to associate in the dilute aqueous solutions through hydrophobic interaction. From the apparent number‐average molecular weight with vapor pressure osmometer, the PVAs having an n‐dodecylthio and an n‐hexadecylthio group at one end were calculated to associate by about five and three molecules, respectively. The aqueous solutions of the PVA having an n‐dodecylthio group at one end showed much higher viscosity compared with the PVA having a hydroxyethylthio group at one end (HOCH2CH2S—PVA) in low concentration regions of below 10 wt % due to the association of the n‐dodecyl end group. Surface tensions of the aqueous solutions of the PVAs having an n‐alkylthio group at one end (n‐CnH2n+1S—PVA) showed almost the same value, which was slightly smaller than that of HOCH2CH2S—PVA, at 4 and 6 of carbon atoms, lowered with an increase in the number of carbon atoms above 8, showed minimum at 12 and then increased at 16 and 18. In the emulsion polymerization of vinyl acetate, n‐CnH2n+1S—PVAs of 10 through 18 carbon atoms acted effectively as a protective colloid.

Surface properties of aqueous solutions of trifluoroacetic and acetic acid mixture

The coadsorption of trifluoroacetic and acetic acid at the free surface of water was investigated. Knowing the composition of mixed monolayer and the effective dipole moments of individual molecules, the surface potential was calculated. The synergetic effect of the surface properties of mixed adsorbed films was observed.

Electrical surface properties of aqueous solutions of 3- and 4-isomers of nitro- and chlorophthalic acids

The electrical surface effect of isomers of nitro- and chlorophthalic acids is strongest at pH <3 when they are in unionized state. 3- and 4-nitro- and 3- and 4-chlorophthalic isomers decrease the surface tension, the more the greater their concentration; however, 4-nitro- and 4-chlorophthalic acids increase the natural surface pd of water.