Abstract
Di-n-hexyl- or tri-n-butyl-carbinyl ethylene glycol monoethers were prepared from 2-n-hexyl-or 2, 2-di-n-butyl-l, 3-dioxolane and appropriate Grignard reagents. These were converted into nonionic surfactants containing two or three alkyl chains in the hydrophobe, (n-C6H13) 2CHO (C2H4O) mH (DC series), (n-C4H9) 3CO (C2H4O) mH (TC series), by the reaction with ethylene oxide (EO). Some surface active properties of these nonionics were examined in comparison with those of tridecanol-EO addcts (S series) and with other conventional nonionics in order to clarify the effects of the multi-chain type hydrophobe. For the same length of polyoxyethylene chain (m), the cloud point decreased in the order; S>TC>DC. Aqueous surface tension of DC- and TC-series was lower than that of S-series. No significant difference in molecular area on adsorbed film was observed between DC, TC and S having comparable m. A linear relation was found for m dependence of cmc in DC-, TC- and S-series. The cmc values markedly increased with increase of the number of alkyl chains in the hydrophobe, being consistent with “Hartleys' principle”. Some gross effects such as wetting efficiency, suspending and emulsifying powers were enhanced by the introduction of multi-chain structure to the hydrophobe, while the foaming properties reduced.
These results were discussed from a viewpoint of the hydration of polyoxyethylene chain and the arrangement of adsorbed surfactant molecules.
