Determination of critical micelle concentration of dendritic surfactant synthesized via a selective ring-opening addition reaction

Abstract

An azetidine-2,4-dione was applied to synthesize dendrons with four carbons in the end ([G-0.5]-C4 and [G-1]-C4) via a selective ring-opening addition reaction, which was subsequently extended to obtain a dendritic surfactant ([G-1]-C4 surfactant) by acidification. The dendrons were characterized by Fourier transform infrared (FT-IR), 1H nuclear magnetic resonance (1H NMR), elemental analyzer (EA), and fast atom bombardment mass spectrometry (FAB MS). The dendritic surfactant, with a cationic head and branched hydrophobic C4 tails, was dissolved in 2wt.% dimethyl sulfoxide (DMSO) aqueous solution for the determination of critical micelle concentration (CMC) by fluorescence and electrical conductivity measurements. The resulted CMC values were very close within measurements, ca. 0.013–0.05mM. Transmission electron microscopy (TEM) and zeta potential measurement also provided an evidence of micelle formation and shape. Moreover, anionic dyes were adsorbed onto the micelles successfully to confirm the positive charge of [G-1]-C4 surfactant.