N-[γ-(二烷基氨基)烷基]全氟辛基磺酰胺类阳离子氟表面活性剂的合成及性质研究

Synthesis and Properties of Cationic Fluorinated Surfactants N-[γ-(dialkylamino)alkyl] Perfluorooctanesulfonamide

摘要:

以全氟辛基磺酰氟(C8F17SO2F)和N,N-二烷基氨基烷基二胺[NH2(CH2)nNR2(n = 2, 3; R = -CH3, -CH2CH3)]为原料，合成了四种N-[γ-(二烷基氨基)烷基]全氟辛基磺酰胺[C8F17SO2NH(CH2)nNR2]，然后用盐酸酸化和用碘甲烷季铵化分别得到相应的四种盐酸盐[C8F17SO2NH(CH2)nN+HR2Cl-]和四种季铵盐[C8F17SO2NH(CH2)nN+R2(CH3)I-]。研究了这些阳离子型氟表面活性剂在水中的溶解性和表面活性，探讨了中间基团（碳氢间隔基）长度和亲水头基大小对该类阳离子氟表面活性剂性能的影响。结果表明适度改变中间碳氢间隔基长度和亲水头基大小对该类阳离子氟表面活性剂的溶解性影响较大，但对其表面活性的影响不很明显，可归因于这类氟表面活性剂的氟碳链的疏水效应太强，掩盖了中间碳氢间隔基长度和亲水头基大小对其疏水性的影响。它们的细微差别可以从溶解性、溶液表面的吸附状态、空间位阻和电荷密度角度解释。

Abstract:

Four N-[γ-(dialkylamino)alkyl]perfluorooctanesulfonamides [C8F17SO2NH(CH2)nNR2, n = 2, 3; R = -CH3, -CH2CH3] were synthesized from the reaction between perfluorooctanesulfonyl fluoride (C8F17SO2F) and N,N-dialkyl-alkanediamine [NH2(CH2)nNR2, n = 2, 3; R = -CH3, -CH2CH3], from which derivative products (four hydrochloride salts [C8F17SO2NH(CH2)nN+HR2Cl-] and four quaternary ammonium salts [C8F17SO2NH(CH2)nN+R2(CH3)I-]) were obtained by acidification with hydrochloric acid and quaternization with CH3I, respectively. The solubility and surface activities of these cationic fluorinated surfactants in aqueous solution were studied. The effects of length of linker group (hydrocarbon spacer) and the size of hydrophilic group on the performance of these cationic fluorinated surfactants were discussed. It showed that these two factors, i.e. such changes in the length of linker (hydrocarbon spacer) and the size of hydrophilic group, could significantly influence the solubility of surfactants but insignificantly influence their surface activity. This could be attributed to the strong hydrophobicity of fluorocarbon chains which overwhelming upon the influence from the length of linker (hydrocarbon spacer) and the size of hydrophilic group. The detailed differences between the behaviors of these surfactants could be explained in the term of solubility, adsorption state on the air/water interface, steric effect and charge density distribution.