Rapid functionalization of single-walled carbon nanotubes in polar solvents

Fluorescent semiconducting single-walled carbon nanotubes (SWCNTs) hold considerable promise for photonics. Furthermore, their optical characteristics can be improved by functionalization, which generates additional spectral features. However, the importance of the solvent in which the SWCNT modification is conducted remains underexplored. In this work, the complex relationships between solvent, dispersant, and SWCNTs were untangled to unravel the underlying phenomena. Through a systematic investigation of SWCNT reactivity in a broad spectrum of solvents, supported by multiscale modeling enabled by our implementation of a hybrid functional within SIESTA, we found that the solvent medium and the dispersant enabling SWCNT solubilization affect not only the kinetics but also the course of the modification of SWCNTs. Polar solvents induced notable structural reorganization of polymers on the SWCNT surface and enhanced charge redistribution at the polymer-SWCNT interface. Consequently, we achieved control over the optical properties of SWCNTs, and the tailored SWCNTs enabled optical detection of cholesterol, a substantial risk factor for cardiovascular diseases.