Preparation And Anticorrosion Properties Of Functionalized Graphene Oxide/epoxy Composites

Graphene oxide（GO）,as one of the most important graphene derivatives,which has attracted intense interest in field of polymer nanocomposites,owing to their two-dimensional structure and intriguing properties,along with abundant oxygen functional groups exsited in their surface.However,GO sheets exhibited aggregations and clusters in the polymer matrix,due to their high surface area and van der Waals’interaction,and the poor dispersion and exfoliation significantly limited their further application.To achieve excellent dispersion and compatibility of GO in polymer,decorating sheets with organic components and nanoparticles is a simple and efficient approach,then functionalized graphene oxide（FGO）is incorporated into polymer to prepare FGO/polymer composite material,finally,we make further studies of dispersion and corrosion protection performance of composite material.In this paper,GO was fabricated via Hummers’ method,then which was modified by silane coupling agents（APS,GPS）and nanoparticles（CaCO₃、Fe₃O₄ and Zr02 NPs）to prepare GO-CaCO₃、GO-Fe₃O₄ and GO-ZrO₂ nanohybrids,respectively.The morphology and structure of nanohybrids were studied by High resolution transmission electron microscopy（HR-TEM）,Field emission scanning electron microscope（FE-SEM）,energy dispersive spectroscopy（EDS）,X-ray photoelectron spectroscopy（XPS）,Fourier-transform infrared spectroscopy（FTIR）and X-ray diffraction（XRD）analysis.Investigations indicated that the NPs and modified GO with the optimal weight ratio of 1:5,and the corresponding nanohybrids of NPs anchored on GO surface with high uniformity and density,and the multilayered stacked structure of GO has been changed into the thin layered structure.The as-prepared GO-CaCO₃,GO-Fe₃O₄ and GO-ZrO₂ nanohybrids were incorporated into epoxy resin（EP）at weight fraction of 2%.The FE-SEM、EDS、XRD analysis revealed the nanohybrids achieved excellent dispersion and high exfoliation within polymer matrix.Then,the GO-CaCO₃/EP,GO-Fe₃O₄/EP and GO-ZrO₂/EP composite coatings were prepared through spraying and curing process.The scanning electron microscope（SEM）,electrochemical impedance spectroscopy（EIS）and water contact angle（WCA）tests were used to evaluate the corrosion protection properties of EP composite coatings.The results indicated that GO-CaCO₃/EP（～86h）took a relatively longer time than the pure EP coating（～20h）to reach the middle stage of corrosion.After 174h of immersion,the GO-Fe₃O₄/EP coating still remained excellent corrosion resistance,while pure EP became invalid.The conversion time from initial to the terminal stage of corrosion was 60 h for neat EP and 380 h for GO-ZrO₂/EP,respectively.After soaking for 20 days,functionalized GO/EP composite coating still maintained the relative large WCA,and the inconspicuous transformation was shown in coated functionalized GO/EP composite coating.These results demonstrated three nanofiller（GO-CaCO₃、GO-Fe₃O₄ and GO-ZrO₂）significantly reinforced the corrosion protection properties of EP composite coatings.At last,the corrosion-resistant mechanisms were represented and tentatively discussed.