Thermally induced solid-state synthesis of fluorine-containing poly(ether oxadiazole)

Abstract

Synthesis of poly[oxy-(2,3,5,6-tetrafluoro-1,4-phenylene)-(1,3,4-oxadiazol-2-yl)-1,4-phenylene] (F-PEOz) was examined by nucleophilic aromatic substitution reaction of 2-(4-hydroxyphenyl)-5-pentafluorophenyl-1,3,4-oxadiazole (HPOz). Only low molecular weight F-PEOz or crosslinked insoluble polymers were obtained by the solution polymerization with bases. In contrast, thermally induced solid-state polymerization of HPOz potassium salts at 180°C for 1 h gave fully soluble F-PEOz with the yield of 84% and its reduced viscosity was 0.66 dL g−1. The longer polymerization time gave insoluble polymers due to the crosslinking reaction even in solid state. The solid-state polymerization did not undergo topochemically and it proceeded in an amorphous state. The crosslinking reaction was slightly inhibited by the solid-state polymerization. F-PEOz exhibited excellent solubility, high Tg of 246°C and good thermal stability. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010