Single-walled carbon nanotubes modified by ionic liquid as antiwear additives of thermoplastics

Pristine single-walled carbon nanotubes (CNTs) were dispersed in the room-temperature ionic liquid (IL) 1-octyl, 3-methylimidazolium tetrafluoroborate ([OMIM]BF4) by grinding and ultrasounds. Excess IL was removed to obtain single-walled carbon nanotubes modified by [OMIM]BF4 (mCNTs). mCNTs were added in a 1 wt.% to polystyrene (PS), polymethylmethacrylate (PMMA) and polycarbonate (PC) to obtain PS + mCNT, PMMA + mCNT and PC + mCNT. The dry tribological performance of the new nanocomposites was studied against AISI 316L stainless steel pins and compared with that of the neat polymers and with the nanocomposites containing pristine carbon nanotubes without IL (PS + CNT; PMMA + CNT and PC + CNT). The maximum wear rate and friction coefficient reduction is obtained for PS + mCNT. Results are discussed upon the basis of optical, SEM and TEM microscopy, thermogravimetric analysis (TGA), Raman spectroscopy, X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS).