Facile preparation of TPU conductive nanocomposites containing polypyrrole-coated multi-walled carbon nanotubes for a rapid and selective response in volatile organic compounds applications

Thermoplastic polyurethane (TPU) conductive nanocomposites were fabricated by using TPU as a matrix and polypyrrole (PPy) coating multi-walled carbon nanotubes (MWCNTs) as conductive filler. The microstructure and gas-sensitive response properties of the nanocomposites to volatile organic vapors (VOCs) were systematically investigated. FTIR and HRTEM verified that PPy was successfully encapsulated on the surface of MWCNTs. FESEM showed that homogeneous dispersion of MWCNTs-g-PPy conductive nanofillers contributed to the formation of continuous conductive networks. The obtained TPU/MWCNTs-g-PPy nanocomposites possessed certain gas-sensitive response selectivity, especially for ammonia gas when compared with other target VOCs. The gas-sensitive response values were in the range of 90–100% with a response time of 40–50 s. An excellent recovery performance at 500 ppm ammonia atmosphere was also achieved. Moreover, the gas-sensitive response values to ammonia showed a good linear relationship with the concentration of ammonia gas. The nanocomposites showed excellent stability in both ammonia and dry-air cycle detection.