Functionalized Alkyne Precursors for Direct Placement of Heteroatoms in Carbon Nanotube Growth

Functionalization of carbon nanotubes (CNTs) with heteroatoms enables covalent attachment, opening up a world of potential material structures. However, common functionalization techniques are hazardous and lack precision. Here, we evaluated an in situ functionalization technique utilizing oxygen-containing alkyne precursors and alkyl-functionalized alkyne precursors coupled with acid vapor treatments. CNTs were successfully derived from propargyl alcohol, propiolic acid, and other heteroatom-containing alkyne species. While there was no substantial increase in the oxygen content of resultant CNT structures (all less than 1% O), Fourier transform infrared spectroscopy (FTIR) revealed subtle incorporations of carboxyl and hydroxyl functionality with propargyl alcohol and propiolic-acid fed growths, including specifying hydroxyl or carboxyl chemistry. These results support the universality of alkyne-promoting chemistries and delineate the limits of stable, heteroatom-bearing alkynes to support point-directed functionalization schemes or reduce the environmental burden of wet chemical synthetic approaches.