Catalytic synthesis of perfluorolyethers

Abstract

Perfluorolyether is characterized by highly chemical inertness, oxidative stability, anticorrosion as well as radiation resistance. It can be used as lubricant especially in harsh environmental conditions. In this work, hexafluoropylene oxide was catalytically polymerized at low temperature using the methods of anionic polymerization, and perfluorolyethers were obtained with number-average degree of polymerization more than 15. CsF and RbF were used as catalysts and their catalytic activities were investigated. Experimental results show that perfluorolyethers with number-average molar masses up to 3 000 g/mol could be obtained using the two kinds of catalysts, respectively. As compared to CsF, the number-average degree of polymerization is higher and the relative molecular mass distribution interval is narrower when RbF is used as catalyst. The effect of factors such as impurities’ content, reaction temperature and reaction time on the number-average degree of polymerization was also investigated. It is found that low impurities’ content and low temperature are beneficial to the generation of high number-average degree of perfluorolyethers. The optimization reaction time is 24 h, and further increase of reaction time does not significantly affect the average relative molecular mass. The product was characterized by IR, ¹⁹F NMR and GC-MS, and the catalytic mechanism was analyzed finally.

Keywords

hexafluoropylene oxide / perfluorolyether / polymerization / purification

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