Investigating cetyltrimethylammonium bromide (CTAB) reverse microemulsions using nuclear magnetic resonance

[摘要] This thesis investigates CTAB/alcohol/hexane/water reverse micelles, where the alcohol is butanol, pentanol, hexanol and heptanol, through the use of nuclear magnetic resonance (NMR). Diffusion and relaxation measurements showed the alcohol is distributed between the reverse micelle (RM) interface and the continuous phase, and exchanges between these two environments. The exchange of pentanol in the CTAB/pentanol/hexane/water RM was investigated using 20 relaxation exchange spectroscopy (REXSY), and was determined to be on the order of milliseconds. The proportion of alcohol in the interface was determined for all microemulsions which decreases as a function of increasing alcohol size. Each microemulsion was investigated by molecular simulations which produced oblate shaped droplets, which was associated with a non-homogeneous distribution of alcohol in the interface. CTAB was determined to be present in solely the interface of the microemulsions with the exception of the CTAB/pentanol/hexane/water RM. The CTAB/pentanol/hexane/water RM behaves differently as initially the CTAB was distributed between the RM and the continuous phase however, after time, the surfactant is re-distributed so that CTAB is present in only the interface. The RM sizes were determined using the CTAB diffusion coefficients. The droplet sizes decreased as a function of alcohol chain length, with the exception of the CTAB/pentanol/hexane/water RM which, after time, gave the largest droplet of all the microemulsions.

[发布机构] University:University of Birmingham;Department:School of Chemistry

[关键词] Q Science;QD Chemistry