氟气氟化含氢氟聚醚制备双端官能团全氟聚醚

Preparation of perfluoropolyether with double terminal functional groups by fluorination of hydrogen-containing fluoropolyether

摘要:

以含氢氟聚醚（E10H）为原料，利用氟氮混合气进行氟化制备了双端羟基全氟聚醚（F-E10H-AL），分别探索了常温氟化、低温氟化及先低温后常温氟化的3种氟化工艺。然后与双三氟甲烷磺酸亚胺锂（LiTFSI）制备成锂离子电解质。采用红外光谱、核磁氢谱和氟谱分析氟化后的产物结构，并采用电化学工作站测试了阻抗和计时电流。结果表明，低温氟化工艺具有较高的氟化效率，在-10℃对E10H直接氟化12h后，分子链上有21.0%的H被F取代，但是产生较多的封端基团CF3O-。当利用六氟环氧丙烷二聚体酯化保护E10H上的羟基时，采用先低温后常温氟化工艺，分子链上有48.3%的H被F取代。最后将氟化产物还原，得到F-E10H-AL，分子链末端基本没有CF3O-，含量为0.7%。结合阻抗和计时电流的数据，计算出F-E10H-AL/LiTFSI的离子迁移数为0.32，高于PFPE-OH/LiTFSI（0.07）。

Abstract:

Using hydrofluoropolyether (E10H) as raw material and fluorinating with a mixture of fluorine and nitrogen, a double-terminated hydroxyl perfluoropolyether (F-E10H-AL) was prepared. Three fluorination processes were explored, including normal temperature fluorination, low temperature fluorination, and first low temperature and then normal temperature fluorination. Then it is combined with lithium bistrifluoromethanesulfonate (LiTFSI) to prepare a lithium-ion electrolyte. The structure of the fluorinated product was analyzed by infrared spectroscopy, hydrogen nuclear magnetic spectroscopy and fluorine spectroscopy. The impedance and chronoamperometry(CA) were tested by electrochemical workstation. The results show that the low-temperature fluorination process has high fluorination efficiency. After direct fluorination of E10H at -10°C for 12 hours, 21.0% of H atoms in the molecular chain is replaced by F atoms, but more CF3O- are produced. When the hydroxyl group on E10H was protected by hexafluoropropylene oxide dimer, the fluorination process of low temperature followed by normal temperature was adopted, and 48.3% of H atoms in the molecular chain were replaced by F atoms. Finally, the fluorinated product is reduced to obtain F-E10H-AL with a CF3O- content of 0.7% at the end of the molecular chain. Combining the impedance and CA datas, lithium-ion transference number of F-E10H-AL/LiTFSI is calculated to be 0.32, which is higher than that of PFPE-OH/LiTFSI (0.07).