Design and Development of a Detector Based on Poly(Lactic Acid)/CNT Composite for Detection of Volatile Organic Compounds

Research subject: 

In recent years, there are so many attractions in the field of effective detection and discrimination of volatile organic compounds (VOCs). Detection of VOCs compounds, are very important in many applications and industries such as air pollution control, air quality control, food packaging, food quality control, disease diagnostic, agriculture etc. The sensitivity and selectivity of the prepared sensors to detect of VOCs needs to improve.   

 Research approach:

 A conductive polymer composite sensitive layer based on poly (lactic acid) as polymer matrix and multiwall carbon nanotubes as conductive filler was prepared to detect of volatile organic compounds (VOCs). For this purpose the porous sensitive layer was prepared by non-solvent induced phase separation (NIPS) method. In this structure, chloroform (low boiling point temperature) was used as the solvent and ethanol (high boiling point temperature) was used as a non-solvent. The sensitive layer was used to detect of toluene, methanol, and chloroform. The structure and morphology of synthesized layer was investigated by means of scanning electron microscopy (SEM) and BET test.

The investigation indicated that the phase separation method induced the open cell morphology into the conductive composite. The BET results showed that the specific surface area of composite increased to 22.3 m2/gr. The experimental results showed that the response properties of porous layers was improved dramatically in comparison with dense layers. It was related to the increase of specific surface area of polymer composite and therefore the increase of diffusion coefficient of analyte molecules into the polymer matrix. Finally the sensitivity and selectivity of porous sensitive layers was investigated based on Flory-Huggins interaction parameter.