A zirconium hybrid polyhedral oligomeric silsesquioxane derivative (Zr-POSS-bisDOPO) is synthesized by the corner-capping and Kabachnik-Fields reactions. It is characterized by Fourier transform infrared spectroscopy (FTIR) and nuclear magnetic resonance spectroscopy (NMR), and then used as a flame retardant in diglycidyl ether of bisphenol A (DGEBA) to endow epoxy resin (EP) with flame retardancy. The flame retardancy, thermal stability, and mechanical properties of the cured EP/Zr-POSS-bisDOPO composites are investigated. The results show that when Zr-POSS-bisDOPO is added by 5-7 wt%, the EP/Zr-POSS-bisDOPO composites pass the UL-94 V-0 rating test. In addition, they have a better flame-retardant effect than pure EP. The combination of Zr atom embedded in the Si-O cubic cage and the two phosphaphenanthrene substituent groups in one corner of cubic cage is expected to realize the Zr/Si/P ternary intramolecular hybrid synergistic effect and achieve the possibility of dispersing metal-POSS cages at a sub-micrometer-scale level into polymer matrix. It also proves that Zr-POSS-bisDOPO produces phosphorus-containing free radicals and terminates the chain reactions in gas phase. Meanwhile the Si-O-Si and Zr-O units are retained in the solid phase, which promote the char formation and enhance the flame retardancy. This kind of Zr-doped POSS will be helpful for developing the new metal-POSS hybrid flame-retardant and polymer composites.
Polyaniline/graphene oxide (GON-An) composites were synthesized by chemically grafting pphenylenediamine (PPDA)-modified graphene oxide (GO) with polyaniline (PANI), which was confirmed by FT-IR, XRD, SEM, TEM, Raman spectroscopy, and XPS analyses. The electrochemical impedance spectroscopy test, brine immersion, and Tafel slopes analysis revealed that compared with GO and PPDA-modified GO (GON), GON-An composites which combined the unique corrosion resistance of both PANI and GO exhibited relatively obvious superiority in improving the corrosion resistance of epoxy coating with the same contents. After being immersed in brine for 35 days, the composite epoxy coating containing 1 wt-% of GON-An(1:2) composites in which the mass ratio of GO and PANI was 1:2, possessed a high impedance of 4×10 9 Ω cm 2 , a high corrosion potential of −0.25 V, and a low corrosion current of 4.119×10 −11 A cm −2 . Furthermore, the anti-corrosive mechanisms of PANI/GO epoxy coatings were discussed.
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