Polyelectrolyte‐grafted carbon nanotubes: Synthesis, reversible phase‐transition behavior, and tribological properties as lubricant additives

Abstract

A novel polyelectrolyte-grafted multiwalled carbon nanotubes (MWCNTsg-PILs) which possesses a hard backbone of MWCNTs and a soft shell of brush-like poly (ionic liquids) (PILs) has been synthesized via the surface atom transfer radical polymerization (ATRP). Chemical structure and the grafted PILs quantities of MWCNTs-g-PILs were determined by FTIR, TGA, and XPS. TEM and FE-SEM observations indicate that the nanotubes were coated with a PILs layer, exhibiting core-shell nanostructures with the PILs chains as the brush-like or hairy shell and the MWCNTs as the hard backbone. Furthermore, the effect of counter-anions on the solubility of MWCNTs-g-PILs was investigated. The results indicate that relative solubility of MWCNTs-g-PILs in various solvents could be switched by anion exchange. This tunable solubility results in the formation of the cycle of reversible phase-transition. Tribological property of MWCNTs-g-PILs as additives in base lubricant 1methyl-3-butylimidaaolium hexafluorophosphate (LP104) was evaluated using an Optimol SRV oscillating friction and wear tester, confirming that MWCNTs-g-PILs are the excellent antiwear and friction-reducing additives, which can amend the tribological properties of base lubricant significantly. This is attributed to the good dispersibility and core-shell structure of MWCNTs-g-PILs. These results reported in this work may open primarily toward constructing a bridge among carbon nanotues (CNTs), ILs, and lubricant additives and secondarily to prove that CNTs (modified CNTs) as lubricant additives are promising candidates. V

Superhydrophobic–Superoleophilic Polythiophene Films with Tunable Wetting and Electrochromism

“…[ 24 , 25 ] The said doping/dedoping process was validated by X-ray photoelectron spectroscopy (XPS), wherein the negatively charged counter ion (in this case PF 6 − from the tetrabutylammonium hexafl uorophosphate (TBAH) supporting electrolyte) was confi rmed to be present only in the wettable polymer nanostructured fi lm state during doping as shown by the presence of the fl uorine (F 1s) and phosphorus (P 2p) peaks (Figure 3 c). [ 26 ] The high-resolution XPS scans clearly show that these unique elemental peaks (due to the dopant) are present only in the wetting fi lm, but are not found in the non-wetting polymer fi lm state after dedoping at 0 V ( Figure S11, Supporting Information). Thus, the superhydrophobic property is actually observed on a non-fl uorinated fi lm , which is rare compared to most artifi cial superhydrophobic surfaces previously reported.…”

A review of recent developments of friction modifiers for liquid lubricants (2007–present)

“…TEM and FE-SEM observations indicated that the nanotubes were coated with PILs layer, exhibiting core-shell nanostructures with PILs chains as brush-like or hairy shell and MWCNTs as hard backbone. The composite was both the excellent anti-wear and friction-reducing additives due to its good dispersibility and core-shell structure [166].…”

New Single-Walled Carbon Nanotubes–Ionic Liquid Lubricant. Application to Polycarbonate–Stainless Steel Sliding Contact

“…The combination of the properties of ILs [6][7][8][9] and carbon NTs [25][26][27][28] could also improve the tribological performance of the suspensions, but there is no precedent of the use of NT dispersions in ILs as lubricants, although functionalized multi-walled carbon NTs chemically modified by an IL have been recently used as additives of IL lubricants in steel-steel contact [29,30].…”