Synthesis And Properties Of Fluorosurfactants Bearing Hexafluoropropene Trimer

Fluorinated surfactants, due to the unique properties such as low surface tension, high chemical and thermal stability, excellent hydrophobicity and oleophobicity, are specially applicable in the fields that not suitable for general hydrocarbon surfactants. However, typical flurorinated surfactants, containing long perfluoroakyl chains that possess high biometabolic stability, high bioaccumulation, long-distance migration, have aroused great concerns because of these ecologic problems. Development of new fluorinated surfactants, as the alternatives of long chain perfluoroalkyl surfactants, has become the focus and development direction of fluorosurfactants.As the development direction of environmentally friendly fluorosurfactants, new generation of fluorosurfactants should take use of short or biodegradable perfluoroalkyl chains as the as the perfluoroalkyl precursors, rendering these fluorosurfactants ecologically benign properties such as low bioaccumulation. However, short perfluoroalkyl chains usually possess poor surface activity, the design and synthesis of short perfluoroalkyl chain containing fluorosurfacants become the key issue in the development of environmentally friendly fluorosurfactants.In our work, hexafluoropropylene trimer was used as the perfluoroalkyl precurcer for the synthesis of a series of perfluorosurfactants due to its abundancy and cheapness. All compounds were characterized by 1H NMR, 19F NMR, MS and IR. By surface activity test, thermogravimetric Analysis (TG), critical micelle concentration (CMC) test, the surface activity and thermostability of the fluorosurfactants were studied. Part of the fluorosurfactant were explored their properties based on their compositions with polymers. The reseach is mainly divided into the following parts:1. In chapter 1, the research and development of fluorosurfactants, including their structure, function, general synthetic strategy, and application filed, were summarized. It was pointed that the main issues that hinder the development of the fluoroscurfactants currently, and the technical keys in developing fluorosurfactants. Finally, according to the development direction of the fluorosurfactants, the study subject proposed in this thesis was the design and synthesis of fluorosurfactants with short perfluoroalkyl chain.2. p-Hydroxybenzenemethanol and hexafluoropropylene trimer were used to synthezie the fluorine-containing intermediate, and followed by reacting with thionyl chloride, amination, etc., in sequence,4 four intermediates of benzylamine with the perfluoroalkyl group were obtained. The four intermediates were reacted with alkyl halides, and more than 30 target compounds were synthesized. The molecular structures of the intermediates and the target compounds were characterized.3. The surface activity of the synthesized compounds was tested by pendant drop method, and the thermostability of part of the compounds was investigated by thermogravimetric (TG) analysis. The results indicated that most of compounds have a good surface activity and thermal stability. The minimum surface tension of some compounds were up to 20 mN/m, critical micelle concentration (CMC) below 1.0 × 10-3 mol/L, meanwhile thermal decomposition temperatures exceeded 260℃.4. A cationic polymer (PEI) was mixed with the above anionic and cationic fluorosurfactant, and their properties were examined. Results showed that the combination with the cationic polymer promoted the surface activity of cationic fluorosurfactant, but precipitated micelles were formed for the combination of the anionic fluorosurfactant with the polymer, and surface activity was also reduced.