Effect of the synthetic strategy on the non-covalent functionalization of multi-walled carbon nanotubes with polymerized ionic liquids

Multiwalled carbon nanotubes (MWCNTs) have been non covalently functionalized with various imidazolium-based polymerized ionic liquids (PILs). Two functionalization methods, starting from ionic liquid (IL) monomers containing a vinyl group, have been explored: a simple solution mixing of MWCNTs and PILs and the in situ polymerization. The resulting hybrid materials have been characterized by infrared and Raman spectroscopy, transmission electron microscopy, zeta potential measurement, thermogravimetric analysis and differential scanning calorimetry, and their dispersibility in various solvents has been evaluated to access the effect of the functionalization. The particle size analysis of MWCNTs/PILs agglomerates in various solvents is also reported. The in situ method allows a homogeneous coating of the MWCNT surface and thus a better dispersion of the nanotubes. The solution mixing method, for which diffusion limitations of the PILs into MWCNT aggregates should exist, does not allow a uniform surface functionalization. Finally, with protic IL monomers showing a tendency for hydrogen bonding, we have produced stable CNT/PIL organo- or hydrogel composites.