TY - JOUR

T1 - Molecular thermodynamic modeling of a bilayer perforation in mixed catanionic surfactant systems

AU - Емельянова, Ксения Александровна

AU - Викторов, Алексей Исмаилович

N1 - Funding Information: We gratefully acknowledge the Russian Science Foundation (project # 16-13-10042) for financial support.

PY - 2018/10/16

Y1 - 2018/10/16

N2 - Perforated bilayers play an essential role in biology and in surface science. Here, we extend the classical aggregation model of catanionic surfactant mixtures to describe perforations in a self-assembled bilayer in aqueous salt. The model predicts that changing solution salinity and anionic-to-cationic surfactant ratio may lead to the spontaneous formation of pores in the bilayer and to the assembly of a micellar network. We estimate the dimensions of an optimal pore as a function of solution salinity and aggregate composition and show that with an increase of concentration of the deficient surfactant in a catanionic mixture, both the diameter and the thickness of the optimal pore decrease. This decrease is stronger for pores enriched in surfactant having a longer tail than for the pores enriched in the oppositely charged surfactant with a shorter tail. Our model helps to quantify the driving forces for the formation of a pore in a catanionic bilayer and to understand its role. For the aqueous mixtures C16TAB/SOS/NaBr and DTAB/SDS/NaBr, our predictions are in reasonable although not quantitative agreement with available cryo-TEM and SANS data. Predicted radii of perforations are in the range of those obtained from SANSdata for perforated bilayer disks.

AB - Perforated bilayers play an essential role in biology and in surface science. Here, we extend the classical aggregation model of catanionic surfactant mixtures to describe perforations in a self-assembled bilayer in aqueous salt. The model predicts that changing solution salinity and anionic-to-cationic surfactant ratio may lead to the spontaneous formation of pores in the bilayer and to the assembly of a micellar network. We estimate the dimensions of an optimal pore as a function of solution salinity and aggregate composition and show that with an increase of concentration of the deficient surfactant in a catanionic mixture, both the diameter and the thickness of the optimal pore decrease. This decrease is stronger for pores enriched in surfactant having a longer tail than for the pores enriched in the oppositely charged surfactant with a shorter tail. Our model helps to quantify the driving forces for the formation of a pore in a catanionic bilayer and to understand its role. For the aqueous mixtures C16TAB/SOS/NaBr and DTAB/SDS/NaBr, our predictions are in reasonable although not quantitative agreement with available cryo-TEM and SANS data. Predicted radii of perforations are in the range of those obtained from SANSdata for perforated bilayer disks.

KW - Perforated bilayers Modeling

UR - http://www.scopus.com/inward/record.url?scp=85056560527&partnerID=8YFLogxK

U2 - 10.1039/c8cp04593c

DO - 10.1039/c8cp04593c

M3 - Article

VL - 20

SP - 27924

EP - 27929

JO - Physical Chemistry Chemical Physics

JF - Physical Chemistry Chemical Physics

SN - 1463-9076

IS - 44

M1 - DOI: 10.1039/c8cp04593c

ER -