Comparing the Surface Chemical Properties and the Effect of Salts on the Cloud Point of a Conventional Nonionic Surfactant, Octoxynol 9 (Triton X-100), and of Its Oligomer, Tyloxapol (Triton WR-1339)
✍ Scribed by Hans Schott
- Publisher
- Elsevier Science
- Year
- 1998
- Tongue
- English
- Weight
- 130 KB
- Volume
- 205
- Category
- Article
- ISSN
- 0021-9797
No coin nor oath required. For personal study only.
✦ Synopsis
The surface-chemical properties, critical micelle concentrations (CMC), and effect of salts on the cloud points (CP) of octoxynol 9 (Triton X-100) and tyloxapol (Triton WR-1339) were compared. The latter nonionic surfactant is essentially a heptamer of the former. Even though the molecular weight of tyloxapol is 7 times larger than that of octoxynol 9, its area per molecule adsorbed at the air-water interface is only twice as large. This suggests an unusual orientation for molecules of tyloxapol at the surface and is in keeping with a plateau that is less horizontal and has a somewhat higher surface tension than the plateaus of most nonionic surfactants. The CMC of octoxynol 9 was 4.4 times larger than that of tyloxapol. Unexpectedly, the CP of dilute aqueous tyloxapol solutions was 28°C higher than that of octoxynol 9 solutions. The salting-out ions Na ؉ , Cl ؊ and SO 4 2؊ lowered the CP of tyloxapol 29% more than that of octoxynol 9. However, because the blank tyloxapol solution started out with a higher CP value, its CPs in the presence of salts were higher than those of octoxynol 9. Pb 2؉ and Mg 2؉ cations salted both surfactants in, raising their CP, Pb 2؉ more extensively than Mg 2؉ .