Covalently Grafted Graphene Oxide/Poly(C_<i>n</i>-acrylate) Nanocomposites by Surface-Initiated ATRP: An Efficient Antifriction, Antiwear, and Pour-Point-Depressant Lubricating Additive in Oil Media

Abstract

Nanocomposites of graphene oxide with polyacrylates with varying numbers of carbon atoms from 10 to 18 were prepared by surface-initiated atom-transfer radical polymerization (SI-ATRP), thereby controlling the density of polymer grafting through regulated molecular weight with narrow polydispersity. The dispersivities of these nanocomposites in oil media depend on the grafted density of polyacrylates on the graphene surface, and the degree of dispersion and stability increase with increasing chain length. After detailed characterization of these nanocomposites, their lubrication properties in terms of antifriction and antiwear behavior in base oil and polyol were evaluated. An optimized loading of 0.04 mg/mL graphene oxide/C18-polyacryalate nanocomposite in base oil and polyol provided improved tribological properties in terms of significant reductions of about 42% and 34% in friction and wear, respectively, as well as an improvement in the pour point, thus qualifying this nanocomposite as a potential antifriction, antiwear, and pour-point-depressant additive for lubricating oils and polyol.