Structural evolution in cationic micelles upon incorporation of a polar organic dopant.
Micelles of cetyltrimethylammonium bromide (CTAB), when doped with increasing levels of 4-ethylphenol, show microstructural transitions from spherical micelles to elongated wormlike micelles, disks, and subsequently to globular and then to tubular vesicles. Wormlike micelles are observed at a dopant-to-CTAB molar ratio of 1:3. At higher dopant ratios (1:1), globular vesicles are observed which transition to tubular vesicles when the dopant becomes the predominant species at a ratio of 3:1. These transitions are reflected in small-angle neutron scattering analysis and, interestingly, can be directly observed through cryo-transmission electron microscopy. The para-substituted phenol is interfacially active and modulates interfacial curvature of the micelles. The observations of microstructure modifications have relevance to the synthesis of mesoporous materials using CTAB as the template.
Singh
Mohit
M
Department of Chemical and Biomolecular Engineering, Tulane University, New Orleans, Louisiana 70118, USA.
Ford
Christy
C
Agarwal
Vivek
V
Fritz
Gerhard
G
Bose
Arijit
A
John
Vijay T
VT
McPherson
Gary L
GL