Synthesis And Characterization Of The Fluorinated Surfactants Based On Short Fluorine Carbon Chain

Due to the high surface activity, excellent chemical stability and heat resistance, super hydrophobic and lipophobic properties, fluorinated surfactant has been widely used in commodity field and various industrial fields. It is an urgen affair to research efficient and environment friendly surfactant.In this work, several conventional fluorinated surfactants and Gemini fluorinated surfactants were synthesized by using low-cost amines (di-n-butylamine, hexamethylenediamine) and3-perfluorohexyl-1,2-epoxypropane as starting materials. The final products include quaternary ammonium salt, amine salt, and sulfonic acid salt fluorinated surfactants.The main results are as flows:1. The synthesis and characterization of surfactants. First, fluorine-containing intermediates were synthesized from the reaction of low-cost amines and3-perfluorinated hexyl-1,2-propylene oxide. Then target products were obtained by ammoniation reaction, quaternization reaction and sulfonation reaction. New products were characterized by FT-IR spectra,1H NMR spectra,19FNMR spectra and MS.2. The surface properties of surfactants. In this study, we mainly investigated the surface properties of the Gemini fluorinated surfactants. The surface properties including critical micelle concentration (cmc), surface tension (γ), temperature resistance, salt resistance, surface excess concentration(Γmax), surface area demand per molecule(Amin) and thermodynamic parameters (△Gagg0,△Gads0,△Hagg0,-T△Sagg0) were investigated by means of surface tension measurements and electrical conductivity measurements. The relationship between the structure and properties was discussed. The result showed that the cmc values of those Gemini fluorinated sufactants were significantly smaller than those of single-chain fluorinated surfactants by two to three orders of magnitude. Futher, Gemini fluorinated sufactants reduced surface tension more efficiently than the single-chain fluorinated surfactants at the same concentration. In addition, Gemini fluorinated sufactants had better properties of temperature resistance and salt resistance. The surface wettability properties of the synthesized Gemini fluorinated surfactants were also studied by a contact angle measuring instrument. The results showed that the surface wettability ability of these Gemini surfactants increased with the increase of concentration and the time. The thermodynamic parameters (△Gagg0,AHagg0,-TASagg0) from electrical conductivity indicated that the micellization of2C6FC3-Me.HCl and2C6FC3-Sul was mainly the process of entropy-driven, while the micellization of2C6FC3-Me was entropy-driven at low temperature and was enthalpy-driven at high temperature.