Synthesis and Properties of Dissymmetric Gemini Surfactants

A series of novel dissymmetric gemini surfactants, C _m H_2m+1COOC₂H₄(CH₃)₂N(CH₂)₃N(CH₃)₂C₂H₄OOCC _n H_2n+1]Br₂ was synthesized and symbolized as m-s–n. The Krafft temperatures and surface tension curves of the dissymmetric gemini surfactants were measured using an electrical conductivity method and a drop volume method. The low Krafft temperatures indicate very good solubility of these esterquat gemini surfactants. With the increasing numbers of carbon atoms in the hydrophobic alkyl chain, the critical micelle concentration (CMC) and the minimum surface area (A _min) decrease, and the efficiency of surface tension reduction (pc₂₀) increases. With the same numbers of carbon atoms in the hydrophobic alkyl chain, the dissymmetric gemini surfactant has a lower CMC and a smaller A _min than the corresponding symmetric gemini surfactant due to the enhanced hydrophobic interactions.