碱处理对聚偏二氟乙烯结构与介电性能的影响

Influence of Alkali Treatment on the Structure and Dielectric Properties of Polyvinylidene Fluoride

研究了碱液浸泡处理对聚偏二氟乙烯(PVDF)结构和介电性能的影响。随着浸泡时间的延长,PVDF膜逐渐出现发黄发黑现象。根据傅里叶变换红外光谱、拉曼光谱、X射线光电子能谱等测试表明,PVDF分子链在高温碱液中发生了脱除氟化氢反应,生成碳碳双键,其中部分被继续氧化成含氧基团。接触角测试和宽频介电谱测试结果显示,PVDF膜在强碱中浸泡22 h后,表面水接触角降至31°,亲水性增加;而随着分子链上共轭双键的增加,界面极化程度增大,低频处的介电常数和介电损耗均显著提高。

The effect of alkaline solution on the structure and dielectric properties of polyvinylidene fluoride(PVDF)was studied.With the increase of immersion time,the color of PVDF gradually turns yellow and deeper.According to results of FT-IR,Raman spectroscopy,and XPS measurements,the PVDF molecular chains in high-temperature alkaline environment were defluorinated to form carbon-carbon double bonds,parts of which were further oxidized to form oxygen-containing groups.The results of the contact angle test and broadband dielectric spectrometer show that after 22 h alkali treatment,the water contact angle on PVDF surface decreases to 31°,indicating that the hydrophilicity is increased.Besides,with the increase of conjugated double bonds on molecular chains,the degree of interfacial polarization is strengthened,leading to a significant increase in dielectric constant and dielectric loss at low frequency.