| With its excellent environmental performance,waterborne coatings were found to be more popular in the coating industry.Graphene is a kind of functional material with excellent comprehensive performance.The effective combination of water-based coatings and graphene will open up a new way for the preparation of high-performance water-based coatings and broaden their application fields.It was found that in order to maximize the effectiveness of graphene modification,it was necessary to solve the problem of dispersibility and stability in waterborne coatings and improve its effective dosage in emulsion.In this paper,the recent development of graphene oxide(GO)modified waterborne coatings was summarized and analyzed from the aspects of preparation methods,process routes and main properties.On this basis,a kind of functional graphene oxide(AGO)was designed and synthesized.Then,two kinds of AGO modified waterborne coatings were designed and prepared by crosslinking,chain extension,phase inversion and radical polymerization,including AGO/self-crosslinking styrene acrylic waterborne coatings and AGO/polyurethane acrylate waterborne coatings.The synthesized AGO was added into styrene acrylic emulsion as a crosslinking agent,and a series of room temperature self-crosslinking styrene acrylic waterborne coatings with different content of AGO(0-1.1 wt%)were prepared by changing the amount of AGO.It was found that with the increase of AGO content,the crosslinking degree of styrene acrylic emulsion increased first and then decreased.When the content of AGO was 0.7wt%,the crosslinking degree of the system was close to 90%.At the same time,with the increase of the amount of AGO,the water absorption of the latex film decreased gradually.When the content of AGO was 1.1 wt%,the water absorption of the latex film was found to reach the lowest value.The acid and alkali resistance test results showed that the acid and alkali resistance of the tested samples was the best when the content of AGO was 0.7wt%.The results of Tafel test curve showed that when the content of AGO was 0.7 wt%,the corrosion current of emulsion paint was found to be the lowest,and the corrosion potential was significantly positive,thus,the corrosion resistance of styrene acrylic emulsion paint was the best.Moreover,AGO was found to be more effective in improving the corrosion resistance of self-crosslinking styrene acrylic emulsion paint compared with the direct addition of GO.The main reason was that the addition of AGO as a crosslinking agent to the styrene acrylic emulsion system could not only enhance the crosslinking degree of the emulsion system,but also enhance the dispersing effect and stability of graphene in the emulsion,thereby maximally giving play to the antiseptic effect of graphene.The designed AGO was added into the waterborne polyurethane acrylate emulsion as a chain extender.Then,a series of AGO/polyurethane acrylate waterborne coatings with different AGO content(0-0.9 wt%)was prepared by changing the amount of AGO.It was found that with the increase of AGO content,the crosslinking degree of the latex film first increased and then decreased,while the water absorption of the latex film first decreased and then increased.The particle size measurement showed that the particle size of the composite emulsion was found to increase with increasing the AGO content.The water contact angle test results showed that the water contact angle of pure polyurethane acrylate latex film was only 85.9° and the water contact angle of latex film was found to increase to 102.0° after modified by 0.5 wt% AGO.Scanning electron microscopy(SEM)results showed that compared with pure polyurethane acrylate latex film,the micro pores on the surface of polyurethane acrylate composite latex film modified by AGO were significantly reduced,and the surface was found to become more compact and smoother.TGA test results showed that compared with pure polyurethane acrylate latex film,the heat resistance of polyurethane acrylate composite latex film modified by AGO was improved to a certain extent,and its 10% thermal decomposition temperature was found to increase by nearly 19℃.The results of Tafel measurement curve showed that when the content of AGO was 0.5 wt%,the corrosion current of emulsion paint was found to be the smallest,and the corrosion potential was obviously positive,thus,the corrosion resistance of polyurethane acrylate composite emulsion paint was the best. |
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