vQRS Based on Hybrids of CNT with PMMA-POSS and PS-POSS Copolymers to Reach the Sub-PPM Detection of Ammonia and Formaldehyde at Room Temperature Despite Moisture

Abstract

Nanocomposite-based quantum resistive vapour sensors (vQRS) have been developed from the assembly of hybrid copolymers of polyhedral oligomeric silsesquioxane (POSS) and poly(methyl methacrylate) (PMMA) or poly(styrene) (PS) with carbon nanotubes (CNT). The originality of the resulting conducting architecture is expected to be responsible for the ability of the transducer to detect sub-ppm concentrations of ammonia and formaldehyde at room temperature despite the presence of humidity. In particular, the boosting effect of POSS is evidenced in CNT-based nanocomposite vQRS. The additive fabrication by spraying layer-by-layer provides (sLbL) is an effective method to control the reproducibility of the transducers’ chemo-resistive responses. In dry atmosphere, the two types of sensors showed a high sensitivity towards both hazardous gases, as they were able to detect 300 ppb of formaldehyde and 500 ppb of ammonia with a sufficiently good signal to noise ratio (SNR > 10). They also exhibited a quick response times less than 5 s for both vapours and, even in the presence of 100 ppm of water, they were able to detect small amounts of gases (1.5 ppm of NH3 and 9 ppm of CH2O). The results suggest promising applications of POSS-based vQRS for air quality or volatolome monitoring.

Keywords

• quantum resistive vapour sensor
• toxic gases sub ppm detection
• ammonia
• formaldehyde
• room-temperature
• nanocomposite
• humidity
• spraying layer-by-layer