The thesis deals with the synthesis and characterization of surfactants derived
from natural products. Physico-chemical properties, such as solubility and
melting points, and surfactant properties, such as dispersion, emulsification,
wetting and foaming were investigated.
A number of surfactants was synthesized from sugars and natural hydrophobic
compounds. Monosaccharides, incl. D-glucose, 2-deoxy -2-amino-D-glucose, Dfructose
and D-(+)-glucono-1,5-lactone, were used for the hydrophilic moiety of
the surfactants. The hydrophobic moiety consisted of steroids, monoterpenes,
rosin acids, fatty acids and long chain alkyl groups, as well as aromatic
compounds. In general, the synthetic procedures gave relatively high yields in
few steps. Some novel surfactants were prepared in high yields in one simple,
synthetic step.
A simple model could not rationalize the general structure-property
relationship of the surfactants since no clear trends could be observed. All
surfactant properties were compared to those of common commercial surfactants.
The aqueous solubility follows the general trend expected from the HLB of the
surfactant when considerations about the character of the head group and the
connecting unit are added. Some surfactants were able to form macroemulsions
between 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, by
using twin chain tail groups, increased the dispersion properties further. The
wetting properties of the sugar-based surfactants were generally found to be
poor. 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 a
good dispersion and emulsification agent. PEG- and sugar-based surfactants of
dehydroabietic acid are good foaming agents with fair wetting properties. The
sugar-based one is also a particularly good dispersion agent.