| 1. |
- Piispanen, PS, et al.
(author)
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Synthesis and characterization of surface-active compounds derived from cholesterol derivatives and glucose
- 2002
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In: Journal of Surfactants and Detergents (JSD). - 1097-3958 .- 1558-9293. ; 5, s. 345-351
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Journal article (peer-reviewed)abstract
- The synthesis and characterization of surface-active compounds based on various steroid derivatives and glucose are presented. The hydrophobic and hydrophilic parts of the compounds were linked via glucosidic bonds. All compounds were found to have very low water solubility and only limited solubility in various organic solvents. The compounds were investigated according to their ability to interact with an anionic surfactant, sodium dodecylsulfate (SDS), in order to induce a decrease in the critical micelle concentration (CMC) of the surfactants. This synergistic effect was pronounced for cholestanol-6-on-ß-d-glucopyranoside and for cholestan-3,6-diol-ß-d-glucopyranoside. These two compounds lowered the CMC from 8 to 6 and 0.6 mM, respectively, for water solutions of SDS/glucoside with a molar ratio of 92:8. Furthermore, the ability of the compounds to stabilize lipid membranes, in liposomes, at varying concentrations of Ca2+, was studied. The compounds were, as expected, found to induce stabilization similar to that of cholesterol
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| 2. |
- Piispanen, PS, et al.
(author)
-
Synthesis and surface measurements of surfactants derived from dehydroabietic acid
- 2003
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In: Journal of Surfactants and Detergents (JSD). - 1097-3958 .- 1558-9293. ; 6, s. 125-130
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Journal article (peer-reviewed)abstract
- Dehydroabietates with poly(ethylene oxide) chains of average m=12, 17 and 45 units (DeHab(E)m) have been synthesized and some of their surfactant properties have been characterized. The results have been compared with common linear chain CnEm surfactants. The adsorption to the liquid-vapor interface was measured and the adsorbed amount and critical micelle concentrations, cmc, determined. The dehydroabietic acid as hydrophobe was found to result in the same cmc as a linear dodecyl chain. The DeHAb(E)45 was found to be insoluble above 400 mg/l, but the surface tension at lower concentrations were similar to those of the C11-13E38-40 surfactants, which exhibit cmcs in aqueous media. The reason for the insolubility of DeHab(E)45 is proposed to be the large size and rigid structure of the hydrophobe, which imposes a large micelle size. The curvature of such a micelle is too low for efficient packing of the large headgroup, so micelle formation becomes unfavorable. The foaming behavior of the DeHAb(E)12 and DeHab(E)17 surfactants was about the same as for common linear CnEm surfactants i.e. the foamability as well as the foam stability increased with ethylene oxide chain length. The cloud point was depressed by increased salt concentration and increased with the number of ethylene oxide units in the head-group. The cloud point was significantly lower than for the corresponding surfactant with a dodecyl chain with similar EO-chain length. The suggested reason for this is explained by the fact that the micelles of DeHab(E)m are larger, due to the large and more rigid dehydroabietic hydrophobe. The attractive forces between the micelles are larger for DeHab(E)m than for the linear CnEm surfactants. The more concentrated surfactant phase of DeHab(E)m leads to clouding phenomenon at lower temperatures than for CnEm. The wetting results, obtained by measuring the contact angle at similar surface tensions, indicate that surfactants of the DeHab(E)m type are more efficient wetting agents than both disaccharide sugar surfactants and CnEm type surfactants.
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