Synthesis And Properties Of Quaternary Ammonium Bola Surfactants

While conventional quaternary surfactants consist of a single hydrophilic group with a single hydrophobic chain,the new Bola-type surfactant differs from the above conventional structure and consists mainly of two hydrophilic head groups and one or two hydrophobic chains.The surface activity of its novel surfactant is better than that of the conventional surfactant,and it can form stable micelles in water,which has attracted the interest of researchers in several novel applications including drug delivery and ion channels.In this paper,three types of quaternary Bola-type surfactants were synthesized based on the structural and functional characteristics of the novel surfactants.（1）BTAE-n and PTAE-n were prepared from brominated alkanes（n=8,10,12）,benzyl chloride andα,α’-Dichloro-p-xylene by substitution reactions with alkyl long chains as linkage groups.The best experimental conditions were determined by single-factor tests,and the final products were purified were characterized by infrared spectroscopy,nuclear magnetic resonance hydrogen spectroscopy,and mass spectrometry.（2）The tetraheaded quaternary surfactant ZTAE-n（n=3,4）with ester and ether bonds as linkage groups was prepared by esterification and substitution reactions using chloroacetyl chloride,polyethylene glycol andα,α’-Dichloro-p-xylene as raw materials.The optimal experimental conditions were determined by single-factor tests,and the purified final products were characterized by infrared spectroscopy,nuclear magnetic resonance hydrogen spectroscopy,and mass spectrometry.（3）The surface properties of BTAE-n、PTAE-n and ZTAE-n surfactants,such as Kraftt point,solubility,emulsification properties,wetting properties,and foaming properties were evaluated.The Krafft points of the three types of quaternary ammonium surfactants were all less than 0°C,and they had good low-temperature solubility.The solubility of the three types of quaternary ammonium salt surfactants showed easy solubility in polar solvents and insolubility in non-polar solvents.In terms of emulsification performance,PTAE-n surfactant has the best emulsification performance,which increases with the increase of hydrophobic chains among the same type of surfactants.Wetting performance was the opposite of emulsification performance.ZTAE-n surfactant exhibited the best wetting performance.In the foam performance,the foam performance decreased with the gradual increase of molecular weight,but all were better than the single-chain surfactants,and BTAE-n surfactant showed the best foam performance.（4）The surface tensions of BTAE-n、PTAE-n、ZTAE-n surfactants and Benzalkonium chloride（BAC）were measured by the drop profile method with respect to the Critical micelle concentration（CMC）and plotted.The curves ofγ-lgc were calculated and the surface chemical parameters such as the saturation adsorption amountг_max and the minimum interception area A_min were obtained.（5）The inhibition activity of three types of quaternary ammonium surfactants as well as the positive drug benzalkonium chloride against three types of Gram-positive,Gram-negative and fungal bacteria was evaluated by Oxford cup method,and the MIC values were observed,and the MIC values of PTAE-10 and PTAE-12 surfactants were lower than those of the positive drug,showing good inhibition activity.The bactericidal activity of the three types of quaternary surfactants at a concentration of 128μg/m L against the three types of bacteria was determined by plate counting method,and PTAE-12 surfactant showed the highest bactericidal rate against the three types of bacteria.