Synthesis And Surface-active Properties Of Novel Quaternary Ammonium Salt Gemini Surfactants

Recently new types of surfactant called Gemini surfactants attracted increasing attention from both industrial and academic fields. Gemini surfactants are a new class of surfactants having two hydrophobic tails and two hydrophilic head groups connected through a linkage adjacent to the hydrophilic head groups in a molecule. They display greater propensity to form micelles and can efficiently reduce surface tension compared with their corresponding conventional single-chain surfactants counterparts.Novel ionic liquid-type quaternary ammonium Gemini surfactants were synthesized and characterized by IR spectra,1H NMR spectra, 13C NMR spectra and MS. The surface properties including surface excess concentration,Γcmc, surface area demand per molecule, Acmc, efficiency in surface tension reduction, pC20, the effectiveness of surface tension reduction,γcmc, critical micelle concentration, CMC, and standard free energy of micellization,ΔGads0 andΔGmic0, were investigated by means of surface tension measurements. The results indicated that compared with those of their corresponding conventional single-chain surfactant counterparts, these novel Gemini surfactants had lower CMC values and could reduce surface tension more efficiently. Gemini surfactants with alkyl chains of moderate length (C12 or C14) showed the best foamability and foam stability.