Electrostatically controlled isolation of debundled single-walled carbon nanotubes from nanoplatelet dispersant

Influence of Trace Amount of Well-Dispersed Carbon Nanotubes on Structural Development and Tensile Properties of Polypropylene

“…Pristine MWCNTs (P-MWCNTs) (purity >90%, average outer diameter of 10–12 nm, and length of 0.1–10 μm) and ODA (CH 3 (CH 2 ) 17 NH 2 , 97%) were purchased from Sigma-Aldrich. The P-MWCNTs were purified by mild oxidation and disentangled with exfoliated ZrP nanoplatelets using our established nanoplatelet-assisted dispersion approach. − The ZrP nanoplatelets were synthesized with length and width of 100 μm and exfoliated to an individual layer thickness of 0.7 nm using tetra( n -butylammonium hydroxide) (Sigma-Aldrich, 1 mol L –1 in methanol), which has been previously reported in detail. − The disentangled MWCNTs were isolated from solution by the addition of acid to coagulate and precipitate the ZrP nanoplatelets. , The disentangled MWCNTs were functionalized with ODA prior to mixing with PP according to our recently reported method . The MWCNTs become hydrophobic after reacting with ODA and precipitate from aqueous solution.…”

“…In this work, we correlate the tensile behavior of a commercial PP containing multiwalled carbon nanotubes (MWCNTs) with the microstructure of the system across broad length scales. Excellent dispersion and compatibilization were achieved using our well-established nanoplatelet-assisted dispersion approach, − followed by subsequent reaction with octadecylamine (ODA), which is a long-chain fatty amine functional group well-known to be miscible with PP. This unique processing method takes advantage of the reversible electrostatic interaction between exfoliated α-zirconium phosphate (ZrP) nanoplatelets, which have a positive surface charge, and lightly oxidized CNTs.…”

“…This unique processing method takes advantage of the reversible electrostatic interaction between exfoliated α-zirconium phosphate (ZrP) nanoplatelets, which have a positive surface charge, and lightly oxidized CNTs. During ultrasonication, the high aspect ratio ZrP nanoplatelets focus mechanical energy within CNT aggregates and promote their individual dispersion in aqueous solvent. − The concentration of energy across the surface of the CNTs prevents significant stretching or bending of the nanotubes during sonication that would otherwise result in the rupture and scission of long CNTs. , The ZrP nanoplatelets may be subsequently removed from solution by the introduction of an acid to disrupt the electrostatic interaction between the ZrP and CNT phases. , We have recently reported that this method results in high yield (>95%) of individually dispersed single-walled carbon nanotubes (SWCNTs) and MWCNTs in aqueous solution, while completely removing any detectable trace of the ZrP nanoplatelets. , …”

“…5,6 The ZrP nanoplatelets may be subsequently removed from solution by the introduction of an acid to disrupt the electrostatic interaction between the ZrP and CNT phases. 25,26 We have recently reported that this method results in high yield (>95%) of individually dispersed single-walled carbon nanotubes (SWCNTs) and MWCNTs in aqueous solution, while completely removing any detectable trace of the ZrP nanoplatelets. 24,26 In our previous work, we showed that after reacting with ODA, the recovered functionalized MWCNTs (F-MWCNTs) are stable in PP and remain well dispersed at up to 2 wt % loading in compression-molded samples.…”

“…25,26 We have recently reported that this method results in high yield (>95%) of individually dispersed single-walled carbon nanotubes (SWCNTs) and MWCNTs in aqueous solution, while completely removing any detectable trace of the ZrP nanoplatelets. 24,26 In our previous work, we showed that after reacting with ODA, the recovered functionalized MWCNTs (F-MWCNTs) are stable in PP and remain well dispersed at up to 2 wt % loading in compression-molded samples. 18 The disentanglement process is extremely beneficial for properties related to the surface area of the F-MWCNTs, such as thermo-oxidative stability, the onset of electrically conductive behavior, and PP crystallite nucleation.…”