Tailoring the self-assembly, interfacial properties and rheological behaviour of sugar-based surfactants

Sammanfattning: Surfactants are important ingredients in many formulated products used in everyday life. Many of these surfactants originates from fossil-based materials and degrades slowly in aquatic systems. As society strives towards having a smaller environmental footprint, surfactants that are non-toxic, biodegradable and can be synthesized from renewable raw materials need to be developed. To this end sugar-based surfactants, or alkylglycosides, is a promising class of surfactants that have the properties that are sought after. To utilize these surfactants to their full potential more knowledge is required about their behaviour both at interfaces and in solution.In this thesis the behaviour of the alkylglycoside C16G2, and how it is affected by small changes in its molecular structure, has been studied with scattering techniques and rheometry. The anomeric configuration was found to have a large impact as β-C16G2 allowed for a more efficient packing of the headgroup, compared to α-C16G2. This is apparent both at interfaces, where the adsorption was higher for the β anomer, and in solution, where β-C16G2 forms very elongated worm-like micelles while α-C16G2 forms shorter cylindrical micelles. The difference in self-assembly affects the rheological behaviour of these solutions where highly viscous, shear thinning and viscoelastic properties reflects the long micelles of β-C16G2, while solutions of α-C16G2 are Newtonian with low viscosity. The effect of introducing a double bond in the tailgroup of β-C16G2 was also investigated, where a significant decrease in Krafft point was seen, while the formation of worm-like micelles and viscous solutions was still evident.