Comparative study of the extraction selectivity of PFO-BPy and PCz for small to large diameter single-walled carbon nanotubes

Abstract

Semiconducting single-walled carbon nanotubes (s-SWCNTs) are fascinating materials for future electronic and optical applications. Conjugated polymer wrapping is one of the most promising methods for mass production of high purity s-SWCNTs. However, its chiral selectivity is relatively inferior to other s-SWCNT production methods. In this paper, the chiral selectivity of two polymers, poly[(9,9-dioctylfluorenyl-2,7-diyl)-alt-co-(6,6′-{2,2′-bipyridine})] (PFO-BPy) and poly[9-(1-octylonoyl)-9H-carbazole-2,7-diyl] (PCz), which are representatives of widely used polyfluorene and polycarbazole families, respectively, were comparatively studied. Both polymers exhibited high selectivity for a subset of existing chiral species in each of the commercially available raw SWCNT materials (CoMoCAT, HiPco, and arc-discharge) which cover a diameter range of 0.6–1.8 nm. Less chiral species were selected by PFO-BPy from small diameter (< 1 nm) raw SWCNT materials, while more from large diameter (> 1.2 nm) raw materials. High chiral purity (6, 5) (> 99%) and (7, 5) (> 75%) solutions were extracted by PFO-BPy and PCz from CoMoCAT materials, respectively. The different chiral angle and diameter selections for different raw materials by both polymers were ascribed to their different geometrical structures and related polymer-tube interactions. Our work provides indispensable information for better understanding the mechanism of polymer wrapping method and improving extraction of single chirality s-SWCNTs.