Effect of backbone chemical structure of polymers on selective (n,m)single-walled carbon nanotube recognition/extraction behavior

Abstract

The development of a simple and facile method to extract single-walled carbon nanotubes (SWNTs) with a specific chirality index is one of the most-crucial issues in the fundamental study and applications of the SWNTs. We have compared the selective recognition/extraction of the SWNT chirality of poly(9,10-dioctyl-9,10-dihydrophenanthrene-2,7-diyl) (2C8-PPhO) to that of poly(9,9-dioctyfluoreny1-2,7-diyl) (2C8-PFO) that are able to extract specific semiconducting SWNTs free of any metallic SWNTs. Vis/NIR absorption, 2D photoluminescence, and Raman spectroscopy as well as molecular mechanical simulations were used to analyze and understand the obtained chiral selective solubilization behavior. We found that 2C8-PPhO selectively extracts and enriches the (8,6), (8,7), and (9,7)SWNTs, whose behaviors are different from that of 2C8-PFO, which preferentially extracts the (7,5), (7,6), (8,6), and (8,7)SWNTs. Our results indicate that 2C8-PPhO preferably recognizes larger-diameter SWNTs with higher chiral angles compared to those recognized by 2C8-PFO. These findings demonstrate that the difference in the non-aromatic ring numbers on the polymers results in different SWNT chirality recognition/extraction behaviors.