There has been a growing interest in the detection and monitoring of CO2 in various fields for industrial concerns and for high food quality packaging. The air quality in the workplace is closely related to the indoor CO2 concentration. In the food packaging, CO2 generated by the microbial metabolic activity is one of the food spoilage indicators. Monitoring of CO2 levels in the foods packed with modified atmosphere packaging (MAP) is also required to ensure the food quality and predict the shelf life. Herein, we report a surface-immobilized chemiresistive CO2 sensor based on single-walled carbon nanotubes (SWCNTs) noncovalently functionalized with a CO2 switchable copolymer containing amidine pendant groups that transform into amidinium bicarbonates in response to CO2. In the presence of CO2 under humid conditions, the generated amidinium bicarbonates from the polymer wrapping increase the concentration and/or liberate the hole carriers in the nanotubes, thereby increasing the net conductance of the sensor. The amidinium moieties revert back to the amidines when purged with a CO2-free carrier gas with a reversible decrease in conductance. We also demonstrate the sensor performance at various RH values and CO2 concentrations and its selectivity to CO2 over the other atmospheric gases such as O2 and Ar.

Switchable single-walled carbon nanotube−polymer composites for CO2 sensing

2019 Spring National Meeting

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