Chemical Decoration of Boron Nitride Nanotubes Using the Billups-Birch Reaction: Toward Enhanced Thermostable Reinforced Polymer and Ceramic Nanocomposites

Abstract

The combination of properties of boron nitride nanotubes (BNNTs) makes them desirable building blocks for the development of functional macroscopic materials with unprecedented electronic and mechanical features. However, these properties have not been fully exploited because their chemical inertness hampers their processing. One solution is to covalently functionalize the BNNTs to assist in their individualization, dispersion, and processing. Here, we show that dodecyl chains can be covalently attached to BNNTs through the Billups-Birch reaction using lithium and 1-bromododecane as reagents. By combining thermogravimetric and spectroscopic analyses, we were able to verify the presence of the alkyl chains that chemically graft to the outermost wall of the nanotubes, as well as unveil the sp2 to sp3 rehybridization. The hydrophobic addends change the dispersibility and individualization of BNNTs in various organic solvents, which we envision will allow the manufacturing of sophisticated materials such as polymer and ceramic nanocomposites with enhanced strength and thermal stability. Furthermore, because of the inherent thermal stability of BNNTs, the alkyl moieties can be easily removed at high temperatures in air without oxidizing the nanotubes. This chemical functionalization provides a straightforward way to tune the properties of BNNTs, which until now has proven to be a formidable undertaking.

Surfactant-assisted individualization and dispersion of boron nitride nanotubes

“…The ability to fabricate macroscopic materials of BNNTs has also been hindered greatly by the poor dispersibility of BNNTs in all solvents. Researchers have attempted to overcome this barrier in a variety of ways, including covalent/non-covalent functionalization, [13][14][15][16][17][18] polymer or peptide wrapping, [19][20][21][22][23][24] co-solvent systems, 25 surfactants, [26][27][28] strong acids, 12,29 and other aromatic and biomolecules. 9,10,[30][31][32][33][34] One promising way to disperse BNNTs into aqueous solution is through the use of surfactants.…”

Boron nitride nanotubes enhance mechanical properties of fibers from nanotube/polyvinyl alcohol dispersions

“…[46][47][48] The specic structural motif and the rigidity of LSZ are also considered to play a role in its selective interaction with nanotubes of different diameters. 46 When interacting with BNNTs of larger diameter (i.e., roughly 7 nm), 19,49 the wrapping of nanotubes by LSZ may have been hindered. Adding TTAB in LSZ solution increases the BNNT concentration in dispersions.…”

“…[14][15][16] This approach preserves the intrinsic properties of nanotubes as compared to the covalent functionalization of tubes, which oen causes permanent changes in the B-N lattice structure and subsequent property deterioration. [17][18][19] In recent work, dispersions of BNNTs in solvents, including dimethyl formamide (DMF) and ethanol, have been integrated with polymer matrices to produce composites and bers. 12,[20][21][22] Particularly, signicant improvement in thermal conductivity was obtained for BNNT-based composites prepared by vacuum ltration of aqueous dispersions of nanotube/polymer mixtures.…”

Modification of Carbon Nanotubes via Birch Reaction for Enhanced HER Catalyst by Constructing Pearl Necklace‐Like NiCo2P2–CNT Composite

“…In liquid ammonia environment, the added sodium disperses between the negatively charged CNTs, and the added 6‐bromohexanoic acid would dissociate readily to yield sodium bromide and the hexanoic acid radical, then the hexanoic acid radical would readily add to the CNTs, inducing the surface of which was alkylated by the (CH 2 ) 5 COO − groups through the formation of covalent bond . Besides, the Birch reaction only grafts the alkyl radicals to the outmost sidewall of CNTs, thus avoiding severe damages to the inner sidewall of the CNTs (Figure S1, Supporting Information) . As one can see from the digital photographs in Figure , the functionalized CNTs show good dispersibility and distinct Tyndall effect in aqueous solution compared with the pristine CNTs (PCNTs).…”