Adsorption of block-copolymers on the surface of carbon nanotubes in organic solvent*

Carbon nanotubes (CNTs), find attractive applications due to their unique properties. In some cases, such as polymer nanocomposites, the processing method requires their dispersion in an organic solvent. The dispersion quality strongly impacts the properties of the final nanocomposite. This research characterizes the adsorption of block copolymers of the styrene-b-4-vinylpyridine family (S4VP) onto multi-walld CNTs (MWCNT) in N,N-dimethyl formamide (DMF), using cryogenic transmission electron microscopy (cryo-TEM) and small angle neutron scattering (SANS) measurements with contrast variation. The results show that the block copolymer adsorbs onto the MWCNT surface as a continuous coverage. PS blocks adsorb more tightly (forming a 20 Å layer containing about 6% PS), whereas P4VP blocks emanate into the solvent forming a thick (110 Å) but dilute (<1%) layer, indicating chain extension. Finally, some comparison will be made with adsorption of S4VP from DMF onto the surface of dispersed single-walled CNTs and graphene nanoplatelets, indicating the effect of surface curvature.