Polypropylene-coated functionalized multiwall carbon nanotubes (PP/f-MWNT) comprising functionalized multiwall carbon nanotubes (f-MWNT) in an amount of from about 0.5 wt. % to about 80 wt. %, based on the total weight of the PP/f-MWNT; and polypropylene (PP) in an amount of from about 20 wt. % to about 99.5 wt. %, based on the total weight of the PP/f-MWNT. A method of making PP/f-MWNT comprising (a) contacting pristine multiwall carbon nanotubes (p-MWNT) with nitric acid to produce f-MWNT; (b) contacting at least a portion of the f-MWNT with a first solvent to form a f-MWNT dispersion; (c) contacting PP with a second solvent to form a PP solution; (d) contacting at least a portion of the f-MWNT dispersion with at least a portion of the PP solution to form a PP and f-MWNT suspension; and (e) drying at least a portion of the PP and f-MWNT suspension to form the PP/f-MWNT.