The surface of poly(p-phenylene-1

3

4-oxadiazole) (p-POD) fiber was fluorinated directly by fluoride (F2).The results of ATR-infrared spectroscopic analysis and X-ray photoelectron spectroscopy(XPS) show that it can effectively generate chemical reactions between p-POD fiber and F2.A mass of CF bonds are formed on the macromolecules of fiber surface and the content of F in the form of CF/C O

CFH and CF2 is 28.2%

which indicates that there are not only substitution reactions but also addition reactions between p-PODs and F2.The curves of thermal gravimetric analysis (TGA) show that there is not impact on p-PODs resistance to high temperature

while the aggregative structures of the fluorinated p-POD fiber are more orderly than those of the original fiber from the wide angle X-ray diffraction pattern.In addition

it takes no change in strength of p-POD fiber after fluorination.Under the condition of 20% concentration sulfuric acid which belongs to the artificial accelerated aging test

the retention of strength of fluorinated p-POD fiber remains 84% which increases by about 90% compared to that of the original fiber.Thus

the acid resistance of p-POD is obviously improved owing to the hydrogen bond formed between F atoms and acid solution which makes the protonation of oxadizoles more harder.Besides

there are compact crosslinking layers formed on the surface of p-POD fiber which can slowdown the aging process.