Wetting properties of nonionic surfactants of homogeneous structure C₁₂H₂₅(OC₂H₄)_xOH

Abstract

The wetting of cotton skeins by aqueous solutions of individual surfactants of structure C12H25(OC2H4)XOH, where x = 4‐8, with homogeneous head groups, and of a Poisson distribution mixture containing an average of 5.5 oxyethylene groups, has been measured at various temperatures using the Draves technique. An individual compound with a homogeneous polyoxyethylene head group is a more effective wetting agent than a Poisson distribution mixture with the same average number of oxyethylene units. Loglog plots of wetting time vs surfactant concentration are linear in the concentration range of 0.25 to 1 g/L. The best wetting agents at any temperature have slopes in the ‐1.5 to ‐1.6 range and Y‐intercepts from +0.6 to +0.7. Wetting in these systems appears to be diffusion‐controlled. The wetting time at 1 g/L concentration is a measure of the wetting effectiveness of the surfactant, because it is roughly inversely proportional to the diffusion constant of the surfactant at that concentration. For materials 30 C or more below their cloud point, temperature increase causes an increase in wetting effectiveness. As the cloud point of the surfactant solution is approached, however, both the slope and the Y‐intercept of the log‐log plot of wetting time vs surfactant concentration change sharply. The absolute value of the negative slope decreases and the positive value of the Y‐intercept increases, resulting in greatly reduced wetting effectiveness.

Changes in Phase Behavior from the Substitution of Ethylene Oxide with Carbon Dioxide in the Head Group of Nonionic Surfactants

“…The surface tension of the CO 2 surfactants at 25 °C at the cmc was found to be between 34.4 and up to 35.9 mN m −1 . This is in the expected range for C 12 EO j nonionic surfactants, but it is interesting to note that surface tension becomes lower with increasing CO 2 content, that is, the surfactants become more effective.…”

Dependence of Phase Behavior of Some Non-ionic Surfactants at the Air–Water Interface on Micellization in the Bulk

“…The appearance of turbidity is believed to be due to the sharp increase in aggregation number and the dehydration of the hydrophilic head groups with increasing temperature (43). The concentration of surfactant in the coexisting homogeneous aqueous phase is equal to the CMC of the surfactant at that temperature (16,(41)(42)(43). However, we did not observe any visible appearance of cloudiness during the experiments.…”

“…This may arise a question about the homogeneity of the solution since it is well known that an aqueous solution of a surfactant becomes turbid on heating to a temperature known as the cloud point. It depends on the structure of a surfactant and its concentration (41,42). The appearance of turbidity is believed to be due to the sharp increase in aggregation number and the dehydration of the hydrophilic head groups with increasing temperature (43).…”

Preparation and evaluation of sulphonamide nonionic surfactants

“…The wetting time of the prepared surfactants was determined by immersing a sample of cotton fabric in 1.0 wt % aqueous solution of the surfactants and measuring its sinking time in seconds (Cohen and Rosen, 1981).…”