Systematically quantifying oil–water microemulsion structures using (spin-echo) small angle neutron scattering

Systematically quantifying oil–water microemulsion structures using (spin-echo) small angle neutron scattering

Mulder, Maarten (Student TU Delft)
Li, Xuesong X. (Shell Global Solutions International B.V.)
Nazim, M.M. (TU Delft ImPhys/Practicum support)
Dalgliesh, Robert M. (Rutherford Appleton Laboratory)
Tian, B. (TU Delft RST/Neutron and Positron Methods in Materials)
Buijse, Marten (Shell Global Solutions International B.V.)
van Wunnik, John (Shell Global Solutions International B.V.)
Bouwman, W.G. (TU Delft RST/Neutron and Positron Methods in Materials)

2019-08-20

Microemulsion systems consisting of D₂O, an alkane, an anionic internal olefin sulfonate surfactant, salt and secondary butyl alcohol (SBA) as co-solvent are studied in a systematic way. In four different sample sets, either the salt content, SBA content or alkane carbon number was varied in order to study the effects of the individual compounds on the structure sizes making up the microemulsion. Using complementary small-angle neutron scattering techniques SANS and Spin-Echo SANS, it was found that the microemulsion systems exhibit the largest structures in the optimum state (domain size of d/2 =144 nm in the model by Teubner and Strey), where the structure is considered bicontinuous. In comparison, at under- and over-optimum states where the structures consist of emulsified spherical droplets, the smallest measured diameter was 2R = 44 nm. Furthermore, the structure sizes in bicontinuous microemulsions decrease exponentially (down to d/2 =15 nm for pentadecane and 5 wt% SBA) as function of both SBA content and alkane carbon number. The observed trends in structure sizes combined with the trends observed in the area per surfactant molecule, are qualitatively explained with the extended Winsor R-ratio, the HLD-NAC model and surfactant film flexibility arguments.

http://resolver.tudelft.nl/uuid:5519da60-7d60-42ed-a149-2c162d28281a

https://doi.org/10.1016/j.colsurfa.2019.04.045

0927-7757

Colloids and Surfaces A: Physicochemical and Engineering Aspects, 575, 166-175

Institutional Repository

journal article

© 2019 Maarten Mulder, Xuesong X. Li, M.M. Nazim, Robert M. Dalgliesh, B. Tian, Marten Buijse, John van Wunnik, W.G. Bouwman