磺化聚苯乙炔/多壁碳纳米管复合材料导电机理研究

Study on Conductive Mechanism of Composites-Sulfonated Polyphenylacetylene/Multiwalled Carbon Nanotubes

将磺化聚苯乙炔(SPPA)与多壁碳纳米管(MWNT)超声共混制备得到SPPA/MWNT复合材料.用四探针电阻率测试、场发射扫描电镜(FESEM)、XPS、UV-Vis、XRD等方法对复合材料导电机理进行研究.结果表明,SPPA/MWNT的电导率发生两次突跃;掺杂剂MWNT具有低的临界阈值;临界阈值附近,复合材料中MWNT具有不连续分布的现象及复合材料电阻呈负温度系数(NTC)效应;SPPA/MWNT复合材料中MWNT的碳原子对SPPA进行掺杂.推测复合材料的导电机理为,共轭聚合物SPPA不仅被导电粒子MWNT物理填充,同时还被MWNT的碳原子掺杂,使复合材料中存在两种导电通路而导电,一是因被掺杂而成为高电导率主体的SPPA相互接触形成的导电通路,二是MWNT相互接触形成的导电通路.

Composites-sulfonated polyphenylacetylene/multiwalled carbon nanotubes （SPPA/MWNT） were prepared by mixing SPPA with MWNT in an ultrasonic bath. The conductive mechanism of SPPA/MWNT was studied by fourprobe, field emission scanning electron microscope （FESEM）, UV-Vis, XPS, and XRD. The results showed that there were two obvious increases of electrical conductivity, the dopant（MWNT） had a low percolation threshod, the MWNT was discontinuously dispersed in the composites when reaching the percolation threshold, and the resistance of the composites showed a negative temperature coefficient （NTC）. XPS ,UV-Vis, and XRD results indicated that SPPA was doped by the carbon atom of MWNT in the composites. The conductive mechanism of the composites was inferred as follows： there were two kinds of conductive networks, one was formed by doped SPPA contacting with each other, the other was formed by MWNT contacting with each other, since the conjugated polymer （SPPA） can be not only filled by MWNT, but also be doped by the carbon atoms of the MWNT.