Microstructural morphologies of CTAB micelles modulated by aromatic acids

Abstract

The morphological changes in cetyltrimethylammonium bromide (CTAB) micelles caused by the presence of three phenylalkanoic acid analogues viz. 3-phenylpropanoic acid (PPA), 3-phenylprop-2-enoic acid (PPE) and 3-phenylprop-2-ynoic acid (PPY) have been examined by ¹H NMR, light and neutron scattering and rheology. Spheroidal CTAB micelles transform into vesicles in the presence of PPY and elongated ellipsoidal micelles with PPE and PPA. The CTAB/PPY system showed an interesting phase transition from vesicles to long rod-like micelles at a temperature of ∼45 °C or at pH ∼9 while CTAB/PPE and CTAB/PPA systems even in alkaline pH (∼9) showed little effect. pH- and temperature-dependent self-assembly of CTAB with analogous aromatic acids behaves differently and may have applications in microfluidics, drag reduction, and encapsulation processes.