Temperature and concentration effects on decyltrimethylammonium micelles in water

Abstract

Wide-angle neutron scattering experiments combined with Empirical Potential Structural Refinement modelling have been used to study the detailed structure of decyltrimethylammonium bromide (C₁₀TAB) micelles at two different temperatures; 25°C and 50°C and two concentrations; 0.4 and 0.8 M in water. At higher temperature, the micelles become smaller, and fewer counterions bind to the micelle surfaces, however, the headgroup positions are more ordered, possibly due to crowding in the smaller micelles. At higher concentration, the models suggest the micelles become elongated, although the aggregations numbers are smaller than those at the lower concentration. The smaller micelles found in 0.8 M solutions have more hydrated headgroups and lower counterion binding than the ellipsoidal micelles found in 0.4 M C₁₀TAB solutions.

GRAPHICAL ABSTRACT

KEYWORDS:

• Micelles
• structure
• ion binding
• wide-angle scattering
• empirical potential structure refinement

Acknowledgements

We thank the STFC for the beam time (RB620144), and for the computing resources provided by the STFC's e-Science facility. The data from this experiment is available at doi:10.5286/ISIS.E.RB620144-1.

Disclosure statement

No potential conflict of interest was reported by the authors.

ORCID

Karen J. Edler http://orcid.org/0000-0001-5822-0127

Daniel T. Bowron http://orcid.org/0000-0002-4557-1929

Additional information

Funding

This work was supported by Science and Technology Facilities Council – ISIS Neutron Scattering Facility [grant number RB620144].