Enhanced conductivity in polybenzoxazoles doped with carboxylated multi-walled carbon nanotubes

TWO representative polybenzazoles, poly(p-phenylene benzobisoxazole) (PBO) and poly(2,5-benzoxazole) (ABPBO), have been used as matrix materials for fabricating electrically conducting nanocomposite films. in this strategy, pristine multi-walled carbon nanotubes (MWCNTs) were first treated with nitric acid to form carboxylated multi-walled carbon nanotubes (MWCNTs-COOH). Subsequently, MWCNTs-COOH were dispersed efficiently in the methanesulfonic acid (MSA) solution of polybenzazole, sonicated, and then processed into thin films. MWCNTs-COOH in MSA formed an isotropic regime at the concentration of similar to 0.1 wt%. Nanotubes could form net like structures and conductive channels in the polymer matrix to improve electrical conductivity mechanical properties, and thermal stability. At the MWCNT-COOH composition of 5 wt.%, polybenzazole/MWCNT-COOH composite films exhibited a dramatic enhancement in electrical conductivity by 8 orders of magnitude from similar to 10(-12) to 1.6 x 10(-4) S cm(-1) without significantly sacrificing optical transparency. (C) 2008 Elsevier Ltd. All rights reserved.