| Marine atmospheric corrosion is a worldwide problem for maritime industries, which seriously shortens the life of metal construction materials, leading to not only huge economic losses but also safety hazards. Protective coating is one of the most common measures for combating marine corrosion. Due to the limitations of technology and capital, the current anticorrosion coatings for marine application are usually detrimental to human and marine ecosystems. Thus, it’s urgent to develop environment-friendly coatings for anticorrosion. Based on the molecular design of waterborne polyurethane and functional materials’ selection, a series of functional waterbome polyurethane (WPU) and their composites for marine application were fabricated. The overall performances of emulsions and coatings were tested and investigated.A series of epoxy modified polyurethane (EPU) emulsions were successfully prepared by using bisphenol-a-type epoxy resin (E-44), polyether polyol (N210, N220), isophorone diisocyanate (IPDI), and dimethylolpropionic acid (DMPA) as main raw materials. The structure of EPU was confirmed by FT-IR, which was in line with the theoretical design. The effect of E-44 content, molecular weight of polyether polyol, the type of chain extender, coating process on EPU were investigated. The optimum properties of EPU were achieved when the E-44 content was 10 wt%, N210 and BDO were chosen as the polyether polyol and chain extender, respectively. In addition, when the heat boning temperature was set as 80℃, the obtained coatings from EPU emulsions had a better performance than others.Based on EPU, a series of waterborne epoxy-modified polyurethane-acrylate (EPUA) emulsions were successfully prepared via a two-step procedure. The carbon-carbon double bond terminated EPU emulsions were first synthesized to serve as seeds, and then the butyl acrylate (BA) and methyl methacrylate (MMA) monomers were introduced into EPU particles to form a polymeric core by radical polymerization. FT-IR revealed the epoxy and polyacrylate (PA) components were successfully incorporated onto the chain EPUA. TEM observation showed core-shell structure of EPUA particles, where PA and EPU acted as dispersed core and outer continuous shell, respectively. The as-prepared EPUA coating films exhibited good thermo-stability and mechanical properties, as revealed by thermogravimetric analysis (TGA) and tensile testing, respectively. The results of potentiodynamic polarization curves and immersion corrosion testing in 5 wt% NaCl aqueous solution both demonstrated that the anticorrosive properties of EPUA were mainly depended on the mass content of PA with the optimized value of 30 wt%.On the basis of EPUA, a series of functionalized graphene oxide enhanced epoxy-modified polyurethane-acrylate (DETDA/GO/EPUA) emulaions were successfully fabricated via a three-step search. Graphene oxide (GO) was prepared through modified Hummers method at first, followed by reacting with diethyl toluene diamine (DETDA) to obtain functionalized graphene oxide (DETDA/GO), and finally DETDA/GO/EPUA emulsions were fabricated of DETDA/GO, EPU and acrylate monomers through emulsion radical polymerization. The influence on the properties of DETDA/GO/EPUA with different DETDA/GO loading level was studied. It turns out that the performance of DETDA/GO/EPUA were highly dependent on DETDA/GO contents. As the addition of functionalized graphene oxide, it not only significantly decreased the water absorption and solvent absorption of DETDA/GO/EPUA coating films, but also improved the thermal stability of films at high temperature. However, both the stability of hybrid emulsion and the anticorrosion performance of DETDA/GO/EPUA coating films became worse at high loading level. At the loading level of DETDA/GO set as 2 wt%, the DETDA/GO/EPUA exhibited the optimal performance in coating application. |
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