Oxidative polymerization of 2,6-difluorophenol to crystalline poly(2,6-difluoro-1,4-phenylene oxide)

Oxidative polymerization of 2,6-difluorophenol was performed using the Fe-salen complex and hydrogen peroxide as catalyst and oxidizing agent, respectively. The resulting polymer obtained at 60 degrees C in 1,4-dioxane was partly soluble in tetrahydrofuran and insoluble in chloroform, benzene, and hexafluorobenzene. The molecular weight of the THF-soluble part was in the range of several thousands. NMR and IR analysis showed the formation of poly(2,6-difluoro-1,4-phenylene oxide). In the DSC trace of second scan, the crystallization temperature and melting point were observed, indicating that the Fe-salen complex enabled the synthesis of crystalline poly(phenylene oxide) from a,6-difluorophenol for the first time.