| Autor: |
Tomlinson, A., Danks, T. N., Heyes, D. M., Taylor, S. E., Moreton, D. J. |
| Zdroj: |
Langmuir; October 1997, Vol. 13 Issue: 22 p5881-5893, 13p |
| Abstrakt: |
The interfacial and nonaqueous solution properties of model engine oil antisludge dispersants have been characterized. Straight chain C8−C18 mono, bis, and tris succinimides were synthesized with polar headgroups of different dimensions and varying nitrogen content. These molecules were found to be poorly soluble in water, as confirmed by log P calculations (P is the partition function between octan-1-ol and water.) Vapor pressure osmometry measurements carried out in acetone and toluene revealed that the mono succinimides show evidence of association into clusters of about three molecules with no noticeable chain length dependence, whereas the bis and tris compounds are essentially unassociated in these solvents. Surface pressure vs area curves from a Langmuir trough exhibit a characteristic plateau at low surface coverage, especially for short chain lengths and mono-substituted succinimides. This feature we attribute to a more compact packing of the headgroups under pressure. For the same lateral pressure the area occupied increases in the order: mono, bis, and tris, correlating well with the number of succinimide moieties in the headgroup. Ellipsometry performed on these molecules deposited on silicon wafers showed that the molecules generally formed excellent close-packed Langmuir−Blodgett films. The succinimides are extremely effective at binding to polar substrates, which is consistent with their practical use. For example, solutions of the various compounds deposited on TLC plates generally showed little movement, and there was the maximum amount of separation in those cases where the solvent had a natural affinity for the headgroup or tail. |
| Databáze: |
Supplemental Index |
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