阳离子型Gemini表面活性剂由多条疏水链段和极性头基在体系中同时作用, 能够更有效降低体系中的表面张力. 但在含氟表面活性剂替代品这一研究领域, 该类结构作为替代品可能性的研究还很少被报道. 本工作设计了以苯环作为中间联接基团, 以CF₃OCF(CF₃)CF₂OCF(CF₃)- (C72), CF₃(OCF₂)₃- (OC3), CF₃(OCF₂)₄- (OC4)和C₅F₁₁- (C6)四种不同含氧量的氟碳链作为疏水链段, 通过季铵化反应合成一系列单链与双链的含氟阳离子表面活性剂, 测定样品在不同浓度下的表面张力来判断样品的表面活性. 从多重角度比较数据, 讨论含氟双子阳离子表面活性剂性能与疏水链上氧原子掺杂程度、以及与样品不同结构之间的规律. 研究结果初步展示了阳离子型Gemini氟醚表面活性剂的独特性, 该结构具有作为长链氟碳表面活性剂替代品的潜力.

The gemini cationic surfactant is a type of surfactant that simultaneously connects at least two hydrophobic hydrocarbon chains and two polar head groups through one intermediate group. Multiple hydrophobic chain segments and hydrophilic groups act concurrently in the system, enabling more effective reduction of the surface tension within the system. However, within the research realm of alternatives to fluorinated surfactants, the potential of the gemini cationic surfactant structure as a substitute has received relatively little attention. In this study, we synthesized tertiary amines using CF₃OCF(CF₃)CF₂OCF(CF₃)- (C72), CF₃(OCF₂)₃- (OC3), CF₃(OCF₂)₄- (OC4) and C₅F₁₁- (C6) methyl esters in methanol solvent at room temperature. Subsequently, a series of gemini cationic surfactants were obtained through the quaternization of the tertiary amine with one benzylbromide and three dibromide compounds in acetonitrile solvent. The reaction conditions for most samples were mild. After purification, the purity of the samples could nearly reach 95%, which rendered the surface activity characterization results more accurate and persuasive. The sample named C72(Et)-o-phenyl-C72, which features diethyl substitution, requires the optimization of reaction conditions. Subsequent purification through column chromatography is necessary to obtain products of high purity. 1% (w), 0.1% (w), 0.01% (w) and 0.001% (w) solutions were prepared for each compound, and the surface tension was measured by the Wilhelmy plate method. The properties of the samples were compared, and the rule between the properties of fluorine-containing gemini cationic surfactants and the degree of incorporation of oxygen atoms on the hydrophobic chain, as well as their different isomers, was preliminarily explored. The results suggest that the characterization results of OC3 and OC4 series samples, of which hydrophobic chain segment featured repetitive -OCF₂O- units, are the most favorable, and the sample properties are minimally affected by the structure. The sample surface activity of C72 series samples, whose hydrophobic chain segment contains only two oxygen atoms, are relatively low, while the sample characterization results of C6 samples, which has no oxygen atoms, are the least outstanding. The results manifest the uniqueness and feasibility of the fluoroether chain segment gemini cationic surfactants, and the structure has potential to serve as a substitute for long-chain fluorocarbon surfactants.