Poly(p-phenylene benzobisoxazole) (PBO) has been synthesized in the presence of singlewall carbon nanotubes (SWNTs) in poly(phosphoric acid) (PPA) using typical PBO polymerization conditions. PBO and PBO/SWNT lyotropic liquid crystalline solutions in PPA have been spun into fibers using dry-jet wet spinning. The tensile strength of the PBO/SWNT fiber containing 10 wt % SWNTs is about 50% higher than that of the control PBO fibers containing no SWNTs. The structure and morphology of these fibers have been studied.

The electrical switching and electrochromic phenomena of a novel nanocomposite comprising poly(p‐phenylenebenzobisthiazole) (PBZT) and tungsten oxide (WO3) nanoparticles are investigated as a function of the nanoparticle loading. Both dissolving PBZT and doping PBZT backbone structure with acid are achieved by one simple step. Chlorosulfonic acid (CSA) is used as a solvent and spontaneously transformed to sulfuric acid upon exposure to moisture. The formed sulfuric acid serves as doping agent to improve the electrical conductivity of PBZT. The most significant enhancement of electrical switching is observed in the nanocomposites with low weight fraction (5%). The electrical conductivity of 5% WO3/PBZT nanocomposite thin film is increased by about 200 times and 2 times, respectively, as compared to those of the as‐received PBZT and PBZT/CSA thin films. As the nanoparticle loading increases to 20% and 30%, the nanocomposites follow an ohmic conduction mechanism. Stable electrical conductivity switching is observed before and after applying a bias on the pristine PBZT and WO3/PBZT nanocomposite thin films. Electrochromic phenomena of both PBZT and WO3/PBZT nanocomposite thin films with high contrast ratio are observed after applying a bias (3 V). The mechanisms of the nanoparticles in enhancing the electrical switching and electrochromic properties are proposed.