Haruhiko Arai

The interaction between polymer and surfactant: The composition of the complex between polyvinylpyrrolidone and sodium alkyl sulfate as revealed by surface tension, dialysis, and solubilization

Abstract The interaction between polyvinylpyrrolidone (PVP) and sodium alkyl sulfate (RSO 4 Na) in 0.1 N NaCl solution has been studied by surface tension, dialysis equilibrium, and solubilization. Two transition points were clearly found on the surface tension vs. concentration curves of RSO 4 Na in the presence of PVP. The first transition point is considered as the concentration at which the adsorption of RSO 4 Na on PVP begins, and the second transition point is considered as that at which the adsorption of RSO 4 Na on PVP is complete. This reasoning was confirmed from the results of dialysis equilibrium and solubilization. The weight ratio of PVP to sodium dodecyl sulfate (R 42 SO 4 Na) consumed for the complete adsorption was constant, i.e. , 1: 2.3 regardless of the amount of PVP in solution. The concentration of RSO 4 Na above which the adsorption of RSO 4 Na on PVP begins was about 40% lower than the respective critical micelle concentration (CMC). The relationship between the logarithm of the CMCs or of the concentration of RSO 4 Na at first transition points and the hydrocarbon chain length of RSO 4 Na was linear. The slope of the first transition point vs. the hydrocarbon chain length agreed with that of the CMC, that is, the free energy of transferring a CH 2 from aqueous solution to the aggregate (complex) or to the micelle is in both cases 1.1 kT . It can be deduced from these results that RSO 4 Na molecules adsorbed on PVP seem to contact each other and not to be uniformly distributed on the PVP molecules right from the initial stages of adsorption.

The interaction between polymer and surfactant: The effect of temperature and added salt on the interaction between polyvinylpyrrolidone and sodium dodecyl sulfate

Abstract The effect of temperature and added salt on the interaction between polyvinylpyrrolidone (PVP) and sodium dodecyl sulfate (SDS) has been studied by surface tension and solubilization. Applying the phase separation theory to the complex formation of SDS with PVP, the heat of complex formation of SDS with PVP (ΔHc) in 0.10 N NaCl solution was calculated from the temperature dependence of the concentration of SDS at the first transition point which appeared clearly on the surface tension or the solubilization vs concentration curve of SDS in the presence of PVP. ΔHc was less exothermic than the heat of micellization (ΔHm) up to 60°C. The relationship between the logarithm of the first transition point and the logarithm of the concentration of counter ion was linear. The slope of the first transition point vs concentration of counter ion agreed with that of the CMC, viz., Kg = 0.52. From the discussion of the results, it was found that the differences between the CMC and the concentration of SDS at the first transition point, as well as those between ΔHm and ΔHc, can be understood from the surface charge density and the free volume of SDS in the absence and in the presence of PVP; the concentration of SDS at the first transition point may be lower than the CMC due to the interaction between the polar group of SDS molecules contacting each other on PVP and that of the PVP molecule.

Interaction between polymer and detergent in aqueous solution

Abstract The interaction between sodium dodecyl sulfate (SDS) and polyvinyl acetate (PVAc) derivatives, that is, polyvinyl alcohol, polyvinyl acetate, and partially saponified polyvinyl acetate, has been studied in terms of the solubilization of Yellow-OB, viscosity, and dialysis equilibrium. The amount of solubilized Yellow-OB decreases with the decreasing hydrophobic character of the polymer. On the other hand, it can be expected that the reduced viscosity of polymer-SDS and the amount of adsorbed SDS on the polymer will take on a maximum value at some most suitable degree of saponification of PVAc. The state of the polymer-detergent complex in detergent solution is discussed as a function of the hydrophobic character of the polymer.

The effect of mixing of oils and of nonionic surfactants on the phase inversion temperatures of emulsions

Abstract The effect of mixing of oils and of surfactants on the phase inversion temperatures (PITs) of emulsions has been studied. The PITs of emulsions in which the oil phase consists of oil mixtures are expressed as follows: PIT (mixture) = PIT (A)·φA + PIT (B)·φb, where φA and φB are the volume fractions of oils A and B, and PIT (mixture), PIT (A), PIT (B) are the phase inversion temperatures of emulsions in which the oil phase consists of an oil mixture, oil A, and oil B, respectively. The PITs of emulsions stabilized with surfactant mixtures changed monotonically between the PITS of the individual surfactants and was always higher than would be predicted from the volume average of the individual PITs. As the PITs (HLB-temperature) and the HLB-value change linearly for a narrow temperature range, the preceding conclusions agree with the findings that (1) the required HLB-value of an oil mixture can be calculated from the volume or weight average of the respective HLB-values of the oils, and (2) the HLB-value of surfactant mixtures does not strictly obey the weight average of the PITS of the constituent surfactants but shows a larger HLB-value than the weight average.

The effect of the size and the distribution of the oxyethylene chain lengths of nonionic emulsifiers on the stability of emulsions

Abstract The effect of the size and distribution of the hydrophilic chain lengths of polyoxyethylene nonylphenylethers and/or polyoxyethylene dodecylethers on the stability of O/W and W/O type emulsions has been studied, using emulsifiers with the same phase inversion temperatures (PITs). The stability for coalescence increases remarkably with the sizes of the lipophilic and hydrophilic groups and shows maximum stability when the distribution of the hydrophilic groups is fairly broad. The substitution for polyoxyethylene nonylphenylether of calcium dodecylbenzene sulfonate also increased the stability for drainage and coalescence. The PIT or the hydrophilic-lipophilic balance (HLB) and the HLB-number are parallel, provided the distribution of the oxyethylene chains of the emulsifiers is similar. But the HLB-number of an emulsifier of broad distribution is lower than that of the pure emulsifier of the same PIT. If the distribution of the hydrophilic chain is broad, the cloud point is lower and the PIT is higher than those of the corresponding sharply distributed materials.

The effect of phase volume on the phase inversion temperature of emulsions stabilized with nonionic surfactants

Abstract The effect of phase volume on the phase inversion temperature (PIT) of emulsions stabilized with nonionic surfactant has been studied. In emulsions composed of saturated hydrocarbons (halogenocarbons) and water, the PIT was nearly constant for a wide volume-fraction range, indicating a marked effect of temperature on the emulsion types. The longer the hydrophilic chain length of the surfactant, the higher the PIT.

The effect of added salt on the interaction between polymer and detergent in aqueous solution

Abstract The effect of added NaCl on the interaction between polyvinyl acetate (PV Ac) and sodium dodecyl sulfate (SDS) has been studied in terms of surface tension, viscosity, and solubilization of Yellow-OB. The surface tension-concentration curve gives two transition points which show the concentration where the adsorption of SDS on PVAc first occurs and where SDS adsorbs totally. The critical micelle concentration (cmc) of SDS and the transition point of PVAC-SDS are lowered by the addition of NaCl. On increasing the concentration of NaCl in the PVAc-SDS solution, the reduced viscosity decreases and the solubilization ability increases. The effect of added NaCl on the PVAc-SDS complex is discussed in terms of electrostatic repulsion.

The relationship between the cloud points and the properties of micelles of nonionic detergents

Abstract The relationship between the cloud points and the properties of micelle of non-ionic detergents has been studied by the light-scattering and the surface-tension methods. With increase in cloud point, the critical micelle concentration increased, and the micellar weight decreased. These relationships were found to hold even in the presence of added salt or alcohol.

The effect of water hardness on the solubilizing activity of linear alkylbenzene sulfonate

The behavior of linear alkylbenzene sulfonate in hard water has been studied by solubilization, transmittance and pH. Maximum solubilization is reported at specific water hardnesses on the basis of the change in the micellar properties of the detergent. The water hardness at maximum solubilization increases as the concentration of the detergent or of sodium tripolyphosphate (STPP), sodium nitrilo triacetic acid (NTA) or sodium ethylene diamine tetra acetic acid (EDTA) increases, while it decreases with an increase in the alkyl chain length of the detergent. A linear relationship between the detergent concentration and the water hardness at maximum solubilization or transmittance was found. It seems that the effect of STPP, NTA and EDTA on solubilization of anionic detergent was mainly due to water softening.

Adherent natural soils on fiber surfaces

Adherent natural soils on fiber surfaces have been studied with the scanning electron microscope. The soils on the fiber surface resemble oily soil.