Chloroform-Dispersed Single-Walled CNT Ink

Chloroform s-CNT inks are prepared from isolating s-CNTs from CNT soot using a previously established procedure.^{43 (link)} Briefly, a 1 : 1 ratio by weight of arc-discharge CNT soot (698695, Sigma-Aldrich) and poly[(9,9-dioctylfluorenyl-2,7-diyl)-alt-co-(6,6′-{2,2′-bipyridine})] (PFO-BPy) (American Dye Source, Inc., Quebec, Canada; #ADS153-UV) are each dispersed at a concentration of 2 mg mL⁻¹ in ACS grade toluene. This solution is sonicated with a horn tip sonicator (Fisher Scientific, Waltham, MA; Sonic Dismembrator 500) and then centrifuged in a swing bucket rotor to remove undispersed material. After centrifugation, the supernatant containing polymer-wrapped s-CNTs is collected and centrifuged for an additional 18–24 h to sediment and pellet the s-CNTs. The collected s-CNT pellet is redispersed in toluene with horn tip sonication and again centrifuged. The centrifugation and sonicating process is repeated a total of three times. The final solution is prepared by horn tip sonication of the s-CNT pellet in chloroform (stabilized with ethanol). s-CNTs prepared via this approach are characterized by a log-normal length distribution with an average length of 580 nm and diameters varying from 1.3 to 1.8 nm.^{44 (link)} Concentration of s-CNT ink was determined using optical cross sections from the CNT S₂₂ transition. This solution is referred to as s-CNT ink in the manuscript.