TY - JOUR
T1 - Systematically quantifying oil–water microemulsion structures using (spin-echo) small angle neutron scattering
AU - Mulder, Maarten
AU - Li, Xuesong X.
AU - Nazim, Mohammad M.
AU - Dalgliesh, Robert M.
AU - Tian, Bei
AU - Buijse, Marten
AU - van Wunnik, John
AU - Bouwman, Wim G.
PY - 2019/8/20
Y1 - 2019/8/20
N2 - 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.
AB - 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.
UR - http://www.scopus.com/inward/record.url?scp=85066115571&partnerID=8YFLogxK
U2 - 10.1016/j.colsurfa.2019.04.045
DO - 10.1016/j.colsurfa.2019.04.045
M3 - Article
AN - SCOPUS:85066115571
SN - 0927-7757
VL - 575
SP - 166
EP - 175
JO - Colloids and Surfaces A: Physicochemical and Engineering Aspects
JF - Colloids and Surfaces A: Physicochemical and Engineering Aspects
ER -