Synthesis and Aggregation of Novel Sugar‐Based Gemini Surfactant with a N, N′‐Acetylethylenediamine Spacer in Aqueous Solution

Abstract

AbstractA novel sugar‐based Gemini surfactant with a N,N′‐acetylethylenediamine spacer (N,N′ (N‐dodecyl‐2‐D‐glucosaminyl acetyl) ethylenediamine, Glu(12)‐(AA)‐Glu(12)), was synthesized with D‐(+)‐Glucono‐1,5‐lactone as starting material in three steps. The surfactant's structure was confirmed using 1H and 13C nuclear magnetic resonance (NMR) spectroscopy and electrospray ionization mass spectrometry (ESI‐MS). The aggregation behavior of Glu(12)‐(AA)‐Glu(12) in aqueous solution at pH 4.0, 7.0, and 10.0 was investigated by surface tension, dynamic light scattering (DLS), and cryogenic transmission electron microscopic (Cryo‐TEM) measurements. The surface tension measurement shows that the critical micelle concentration (CMC) of Glu(12)‐(AA)‐Glu(12) is at the concentration level of 10−5 mol·L−1 at 25 °C, which is significantly lower than that of corresponding monomeric sugar‐based surfactants. Compared with such sugar‐based Gemini surfactants with similar hydrophilic spacers, Glu(12)‐(AA)‐Glu(12) demonstrated similar or slightly lower surface activity. The CMC value of Glu(12)‐(AA)‐Glu(12) underwent a slight decrease with the increase of pH. DLS and Cryo‐TEM measurements reveal that Glu(12)‐(AA)‐Glu(12) forms micelles at acidic pH (pH 4.0) and the micelles are transformed into vesicles at neutral or high pH (pH 7.0, 10.0). The microstructural transformation of Glu(12)‐(AA)‐Glu(12) aggregates is related to the protonation state of its two tertiary amines in the head groups versus pH.