Synthesis and Characterization of Surfactants Based on Natural Products PDF
70 Pages·2002·1.412 MB·English
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The thesis deals with the synthesis and characterization of surfactants derivedfrom natural products. Physico-chemical properties, such as solubility andmelting points, and surfactant properties, such as dispersion, emulsification,wetting and foaming were investigated.A number of surfactants was synthesized from sugars and natural hydrophobiccompounds. Monosaccharides, incl. D-glucose, 2-deoxy -2-amino-D-glucose, Dfructoseand D-(+)-glucono-1,5-lactone, were used for the hydrophilic moiety ofthe surfactants. The hydrophobic moiety consisted of steroids, monoterpenes,rosin acids, fatty acids and long chain alkyl groups, as well as aromaticcompounds. In general, the synthetic procedures gave relatively high yields infew steps. Some novel surfactants were prepared in high yields in one simple,synthetic step.A simple model could not rationalize the general structure-propertyrelationship of the surfactants since no clear trends could be observed. Allsurfactant properties were compared to those of common commercial surfactants.The aqueous solubility follows the general trend expected from the HLB of thesurfactant when considerations about the character of the head group and theconnecting unit are added. Some surfactants were able to form macroemulsionsbetween water and different oils. The emulsions were stable for several months.Surfactants with open sugar head groups, in contrast to closed sugar head groups,were found to be better dispersion agents. Increasing the size of the tail group, byusing twin chain tail groups, increased the dispersion properties further. Thewetting properties of the sugar-based surfactants were generally found to bepoor. Foaming properties were low for surfactants with low aqueous solubility.Some surfactants were found to be particularly interesting: 1-deoxy -1-octylamino-D-glucitol is a very good foaming and wetting agent, as well as agood dispersion and emulsification agent. PEG- and sugar-based surfactants ofdehydroabietic acid are good foaming agents with fair wetting properties. Thesugar-based one is also a particularly good dispersion agent.
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