Key role of the linker in pyrene-linker-carboxylate surfactants for the efficient aqueous dispersion of multiwalled carbon nanotubes

Abstract

. (2015) 'Key role of the linker in pyrene-linker-carboxylate surfactants for the ecient aqueous dispersion of multiwalled carbon nanotubes.', RSC advances., 5 (115). pp. 95360-95368.Further information on publisher's website:http://dx.doi.org/10.1039/C5RA20250GPublisher's copyright statement:Additional information: Use policyThe full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-prot purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details. This study establishes that the structure of the linker group between the hydrophobic and hydrophilic units in the new surfactants 1-13 plays an important role in the dispersibility of multiwalled carbon nanotubes (MWNTs) in water. Systematic variation of the linker group in amphiphilic surfactants for carbon nanotubes has not been previously investigated. In the present series, the hydrophobic unit is derived from pyrene, the hydrophilic unit comprises 1-9 carboxylate groups and the linker is based on amide or ether moieties. The resulting MWNTsurfactant dispersions, up to concentrations and efficiencies of ca. 160 mg L -1 and almost 50%, respectively, have been characterised by UV-Vis absorption spectroscopy studies which provide detailed structure-property relationships, while transmission electron microscopy (TEM) was used to confirm that the MWNTs were well dispersed. For many of the new surfactants enhanced dispersion efficiency is observed compared to commercial surfactants. The efficiency of dispersion is affected by the presence, functionality and particularly the length of the linker, and also the number of terminal carboxylate units. The marked effect of sodium, potassium and calcium cations on the dispersion behaviour is explained by interactions between the metal ions and the surfactant and an ionic screening mechanism. We also demonstrate that the dispersibility of the MWNT-surfactant dispersions can be reversibly switched "off" and "on" by addition of acid and base, respectively. The experimental results are supported by theoretical calculations of solvation energy ΔE S . This study represents a significant advance in the design of multi-functional surfactants for efficient aqueous dispersion of carbon-based materials.

Formation of Two-Dimensional Micelles on Graphene: Multi-Scale Theoretical and Experimental Study

“…0.01 eV to sliding and rotation parallel to the sheet. − This results in a desirable combination of (i) strong adsorption of the surfactants onto graphitic surfaces, and (ii) free lateral movement over them. Surfactants 1 – 4 were synthesized as described previously …”

“…The recently synthesized family of surfactants 19 (see Figure 1) contain pyrene groups for stable planar anchoring to the graphene surface, connected by oligoethylene glycol (OEG) chains to hydrophilic head groups derived from Newkome dendrons. 20 Pyrene is known to bind to graphene with a binding energy of −1.09 eV, and to experience a low energy barrier of ca.…”

Binder‐Assisted Dispersion of Agglomerated Carbon Nanotubes for Efficiently Establishing Conductive Networks in Cathodes of Li‐Ion Batteries

“…In a CNT–PVDF–NMP suspension, PVDF molecular chains would coat onto CNT surface due to the strong interaction between PVDF and CNTs. [ 23 ] As a result, the solid solution interaction between CNTs and the PVDF–NMP solution would be significantly promoted, as compared to that between CNTs and pure NMP. We further tested the viscosities of the CNT–PVDF–NMP suspensions.…”

Functionalization of Carbon Nanotubes with Stimuli- Responsive Molecules and Polymers

“…Nevertheless, it is worth remarking that this work did not clearly address whether the complexation between 4 and 5 was altered on the CNT sidewall with changing pH, and such an issue may deserve further investigation. In 2015, Bryce and Lambert [59] synthesized a total of 13 amphiphilic surfactants, the structures of which were made of a pyrene head (hydrophobic) and various hydrophilic tails ending with carboxylate groups. Similar to the design of numerous other CNT dispersants, the pyrene group here was employed to act as a strong graphenophile to irreversibly link the surfactant molecules to the surface of CNTs.…”

“…Pyrene-based surfactants 6 and 7 that show pH-responsiveness in dispersing MWNTs. The inset scheme was adopted from reference[59] with permission.A novel dumbbell-shaped 2-ureido-6[1H]-pyrimidinone (UPy)-based fluorene derivative 8 (…”