Organic compound gas detector based on polylactic acid/poly (styrene‐co‐acrylonitrile)/multi‐walled carbon nanotube blend composite with co‐continuous microstructure

A conductive polymer composite (CPC) based on polylactic acid (PLA)/poly (styrene‐co‐acrylonitrile) (SAN)/multi‐walled carbon nanotubes (MWNT) blend was prepared and used as a sensitive layer for detecting methanol, ethanol, toluene, and water vapor. The response behavior of polymer blend nanocomposite in comparison with PLA‐MWNT and SAN‐MWNT sensitive layers was studied as well as the influence of solution blending on the morphology, electrical behavior, and performance parameters of prepared sensitive layers. The scanning electron microscopy micrograph results showed that the PLA/SAN solution blended with a 50/50 wt% ratio had formed the co‐continuous morphology. In addition, the electrical conductivity investigation revealed that the percolation threshold of sensitive layers decreased from 1.5 vol%, related to PLA‐MWNT, to 0.8 vol%, related PLA/SAN blend nanocomposite. Thermodynamic investigation revealed that, in the solution blended conductive composites, MWNTs are preferentially localized in the PLA phase. The relative response (Rrel) of blended conductive composite, in comparison with PLA‐MWNT, was increased toward ethanol and toluene vapor while it was decreased against the methanol vapor. The sensitivity behavior of polymer blend composite was investigated based on the double percolated conductive network as well as the thermodynamic parameters such as Flory‐Huggins interaction parameter and solubility parameters.