Transducing Metal Catalyst Reactivity to Selective Chemical Sensing with Pentiptycene Metallopolymer/Single-Walled Carbon Nanotubes Suprastructural Complexes

Single-Walled Carbon Nanotubes (SWCNTs) possess desirable electronic properties to function as the transducer material in a chemiresistive sensor. However, pristine SWCNTs make poor chemical sensors as they lack the functionalities for the selective molecular interaction with target analytes. Our group has demonstrated that catalysis can be a powerful design principle for chemical sensing. By taking advantage of the high reactivity and chemoselectivity of the metal catalysts, we can build chemical sensors with high sensitivity and selectivity that mirror the catalytic processes. To this end, it is essential to develop a general methodology for the seamless integration of metal catalysts in SWCNT-based chemiresistors that can facilitate the effective transduction of the desired chemical interactions to electrical sensing readouts.<br/>In this project, we show that by using a family of pentiptycene-containing conjugated polymers, which are found to effectively bind SWCNTs to form stable dispersions, we can chelate metal catalysts to form suprastructural complexes that are capable of translating the reactivity of the embedded metal catalysts to the selective detection of gas analytes. Chemiresistive chemical sensors constructed based on these metallopolymer/SWCNT complexes find applications in diverse areas such as environmental monitoring and health diagnostics. In particular, we demonstrate that by incorporating a methane oxidation catalyst in these metallopolymer/SWCNT complexes, we can detect the potent greenhouse gas in high humidity at room temperature, overcoming the weakness in most chemiresistive methane sensors. Moreover, we have built a sensitive and selective sensor for the detection of ammonia in breath, which is an important biomarker for the screening and monitoring of chronic kidney disease. For better utility, wearable sensors can also be realized by immobilizing the metallopolymer/SWCNT complexes on flexible substrates. Furthermore, by varying the metal catalysts and tuning the polymer ligand structures, these hybrid sensory nanomaterials can be readily derivatized to construct sensor arrays for the accurate classification and differentiation of analytes in a complex mixture.