Graphene/Polyaniline Nanocomposites And Its Application In Anticorrosion Coatings

With the outstanding mechanical performance, conductivity, thermal stability and shielding effect, graphene is suitable to be the functional filler for reinforcement in the coatings system. However, the research of graphene applied in coatings system is at the initial stage. In this thesis, modified graphene oxide(PGO) was prepared by the functionalization of graphene oxide(GO) with p-phenylenediamine(PPD). Furthermore, formed of PGO and polyaniline(PANI), the PGO/PANI nanocomposites were applied in the anticorrosion coatings to investigate how the nanocomposites affect the performance of the coatings.(1) GO was prepared by modified “Hummers” method. PGO was produced by the modification reaction between PPD and GO via facile refluxing. After the modification by PPD rigid molecule, PGO possessed larger interlayer distance. In the FTIR spectra of PGO, the peak of C-NH-C proved that PPD was successfully grafted onto the surface of GO. In the Raman spectra, PGO had wider G peak with larger ID/IG than that of GO, which inferred the increased disorder. Plannar structure of PGO with folds and better rigidity appeared in SEM image. The higher thermostability of PGO represented the partial reduction during modification. With amino on the surface, PGO was able to disperse in acidic conditions, which made it possible for the in situ polymerization with PANI.(2) The PGO/PANI nanocomposites were synthesized by in situ chemical oxidation polymerization. The vibration absorption peaks of benzene ring and quinone ring showed blue shifts in the FTIR spectra, while the electron transition peaks of benzene ring and quinone ring showed red shifts in the UV-Vis spectra, indicating that the PANI connected with PGO to form greater π electron delocalization. XRD pattern manifested no characteristic peak of PGO revealing the high exfoliation. SEM images presented that PANI grew on the PGO surface in the form of nanoparticles and transformed into nanorods with the longer reaction time.(3) The anticorrosion coatings were gained by solution blending with polystyrene as the film forming material and PGO/PANI as the functional fillers. With the reinforcement of PGO/PANI composites, the anticorrosion efficiency of the films increased from 85.16% to 99.9% and a positive correlation between the anticorrosion performance and the content of PGO was found inferring that PGO played a leading role in the nanocomposites. Besides, the film with the PGO/PANI possessed better performance than the one with PGO or PANI individual which verified that the composites enjoyed the synergism of PGO and PANI. What’s more, the Electrochemical Impedance Spectroscopy(EIS) emerged the Warburg impedance component, concluding that PGO well dispersed in the film was capable to slow down or even defend the permeation of the corrosive material from the environment.