Room temperature amine sensors enabled by sidewall functionalization of single-walled carbon nanotubes

Abstract

A new series of sidewall modified single-walled carbon nanotubes (SWCNTs) with perfluorophenyl molecules bearing carboxylic acid or methyl ester moieties are herein reported. Pristine and functionalized SWCNTs (p-SWCNTs and f-SWCNTs, respectively) were characterized by X-ray photoelectron spectroscopy (XPS), Raman spectroscopy and scanning electron microscopy (SEM). The nitrene-based functionalization provided intact SWCNTs with methyl 4-azido-2,3,5,6-tetrafluorobenzoate (SWCNT-N-C6F4CO2CH3) and 4-azido-2,3,5,6-tetrafluorobenzoic acid (SWCNT-N-C6F4CO2H) attached every 213 and 109 carbon atoms, respectively. Notably, SWCNT-N-C6F4CO2H was sensitive in terms of the percentage of conductance variation from 5 to 40 ppm of ammonia (NH3) and trimethylamine (TMA) with a two-fold higher variation of conductance compared to p-SWCNTs at 40 ppm. The sensors are highly sensitive to NH3 and TMA as they showed very low responses (0.1%) toward 200 ppm of volatile organic compounds (VOCs) containing various functional groups representative of different classes of analytes such as benzene, tetrahydrofurane (THF), hexane, ethyl acetate (AcOEt), ethanol, acetonitrile (CH3CN), acetone and chloroform (CHCl3). Our system is a promising candidate for the realization of single-use chemiresistive sensors for the detection of threshold crossing by low concentrations of gaseous NH3 and TMA at room temperature

Electrically-Responsive Reversible Polyketone/MWCNT Network through Diels-Alder Chemistry

“…Accordingly, the D/G ratio decreases from 1.49 for pristine MWNTs to 1.29 for PK-Fu functionalised MWCNTs. This suggests that after the cycloaddition step subsequent rehybridisation restores the sp 2 state, recovering the aromaticity of the system in the defect region of MWCNTs, as recently reported [31]. Highly defective graphene layers can also be followed by the key analysis of intensity ratio between G’ and D bands, that increases from 0.17 for pristine MWCNTs to 0.27 for the less entangled PK-Fu functionalised MWCNTs (see Figure S4).…”

Versatile Multi-Functional Block Copolymers Made by Atom Transfer Radical Polymerization and Post-Synthetic Modification: Switching from Volatile Organic Compound Sensors to Polymeric Surfactants for Water Rheology Control via Hydrolysis

“…A comparison between two successive exposure cycles of CHCl 3 is displayed in Figure 10a, with the first cycle giving an overall variation in resistance of about 3%, while the second display a slightly lower variation of 1.6%, both determined at the maximum vapours concentration (100 ppm). Same experiments were performed using THF as the solvent, as shown in Figure 10b, resulting in a similar trends in terms of reduced resistance variation for the second cycle, thus suggesting a loss of sensitivity after the first VOC exposure according to similar nanocomposite devices already investigated in the literature [48]. Nevertheless, the system is able to discriminate different VOCs, according to the solvent affinity with the polymer matrix.…”

Carbon Nanotube Chemical Sensors

“…The sensors show no interference from volatile organic compounds and are operational in air and under high humidity. 125…”