Stable aqueous dispersion of polymer functionalized graphene sheets from electrochemical exfoliation for anticorrosion application

Abstract

A green approach of achieving stable aqueous dispersion of graphene by noncovalent functionalization using hydrolyzed styrene-maleic anhydride copolymer has been successfully accomplished. The alkaline solution of hydrolyzed styrene-maleic anhydride copolymer was used as the electrolyte during the electrochemical exfoliation of graphite and simultaneously functionalized the exfoliated graphene sheets. The formation of single-layer graphene was confirmed by X-ray diffraction, atomic force microscopy, and transmission electron microscopy analyses. Fourier transform infrared spectroscopy, Raman spectroscopy, X-ray photoelectron spectroscopy and thermogravimetric analyses confirm the existence of hydrolyzed styrene-maleic anhydride copolymer on the surface of graphene via noncovalent interaction. The results of electrochemical measurements performed in 3.5 wt% NaCl solution indicated that the addition of well-dispersed hydrolyzed styrene-maleic anhydride copolymer functionalized graphene (SMA-graphene) into waterborne organic silicone resin system remarkably improved anticorrosion performance compared with pure waterborne organic silicone resin coating. This significantly enhanced corrosion protection is mainly due to the longer and circuitous diffusion pathway of the corrosive medium derived from highly dispersed SMA-graphene sheets in the composite coating.