pH值对聚苯胺的结构和导电性能的影响

基于酸浓度对苯胺聚合具有较大的影响,采用化学氧化法,在不同pH值条件下制备了聚苯胺,利用FT-IR、UV-V is、XRD对产物的光学吸收、凝聚态结构进行研究,并测定了样品的电导率。结果表明,当pH≥3时有偶氮链生成,并随pH值增大偶氮链增多;苯胺聚合生成具有良好结晶性的低聚物,且随pH值增大,低聚物的电导率急剧降低。当pH≤3时苯胺主要以首-尾连接方式聚合;随着pH值由2减小到0时,所获得的聚苯胺的紫外吸收光谱发生显著红移,其凝聚态结构由一种结构向另一种结构转化;只有当pH≤1时才能合成电导率较高的聚苯胺;当pH值由4减小到0时,聚苯胺的电导率增加了9个数量级。

The Effect of pH on the Structure and Conductive of Polymers

Based on the great effect of acid concentration on the aniline polymerization,polyaniline samples have been prepared by chemical oxidation method.The optical absorbance,morphology structure of polyaniline samples has been investigated by FT-IR,UV-Vis spectroscopy,XRD.The conductivity of polyaniline samples has been investigated by four-probe.The results show that azo-chain is generated when the pH ≥ 3 and azo-chain increased with pH value increasing.Aniline polymerizes and generates good crystalline low polymers when the pH ≥ 3 and conductivity of the low polymers decrease sharply with pH value increasing.The polyaniline samples have a predominantly ＂head to tail＂ arrangement when pH≤3.The absorption wavelength in UV-vis spectra appeared red shift,and the morphology structure transformed one structure to anther as the pH increased from 2 to 0.The polyaniline with high conductivity can only be obtained in a strong acidic condition when pH≤1;it is remarkable to find that the conductivity increases by nine order as the pH changed from 4 to 0.