Study On Acrylate Emulsion Polymerization Behavior Of Graphene Hydration And As A Stabilizer

Water-based acrylate copolymer coatings are durable,have good air permeability,are cost-effective and environmentally friendly.They have become the preferred coatings for interior and exterior wall coatings and textile coatings.However,when used in water-based anticorrosive coatings,they have high "breathability" and are prepared by traditional emulsion polymerization.The presence of the free emulsifier of the type acrylate emulsion leads to low salt spray resistance and poor water resistance of the paint film.Graphene has always been considered as the most promising way to solve the low salt tolerance of water-emulsion acrylic anticorrosive coatings,but its uniform and stable dispersion in water-based coatings has always been a problem.Whether graphene can be hydrophilically modified into a particle-shaped emulsion polymerization stabilizer to solve the problem of stable dispersion of graphene in water-based coatings,and then to improve the anti-corrosion performance of water-emulsion acrylate copolymer coatings has become today's water-emulsion type anticorrosion The main research direction in the field of coatings.In the thesis,graphene oxide(GO)was obtained by the improved Hummers method,partially reduced with sodium borohydride(NaBH4)to restore its conjugated structure,and then sulfonated SRGO by the diazonium salt method.Then use the obtained sulfonated graphene(SRGO)as a stabilizer,and set different formulas with monomers such as styrene(St),methyl methacrylate(MMA),butyl acrylate(BA),and methacrylic acid(MAA).The acrylate copolymer emulsion was prepared by emulsion polymerization,and its emulsion polymerization behavior was explored under different conditions.And the influence of the type and content of SRGO on the anticorrosive performance of the coating was investigated.The main work of this paper is as follows:(1)Preparation of sulfonated graphene and characterization of its structure and properties.GO was prepared by the improved Hummers method,pre-reduced with NaBH4 to obtain RGO,and then RGO was sulfonated and modified by the diazonium salt method to obtain SRGO with better hydrophilicity.The structure was characterized by TEM.The lamellar structure with a lateral dimension of several microns,the number of layers is about 2-5,and the surface has wrinkles.The FTIR and the TG characterization verified the presence of-SO3H on SRGO.Through XPS characterization,it is found that the degree of sulfonation of SRGO is positively correlated with the content of aryl diazonium salt.At the same time,it is found that the hydrophilicity of graphene modified by sulfonation is by observing the dispersion of graphene in water before and after modification and the contact angle test.The properties of SRGO are improved,and the hydrophilicity of SRGO is positively related to its sulfonation degree.The S element content of SRGO-2 used as Pickering emulsion stabilizer is 3.01%,and the ? is 35.4±3°.(2)Study on the Pickering emulsion polymerization behavior stabled by sulfonated graphene.Firstly,50wt%St and 50wt%BA were used as the oil phase,SRGO-2 was used as a stabilizer,and the Pickering monomer emulsion was prepared by high-speed dispersion at 10000 RPM for 10 min.The emulsification ability of SRGO-2 can be judged by the layering of the emulsion and the microscopic morphology of the emulsion droplets.It was found that as the content of SRGO-2 increased,the appearance of the emulsion gradually became unobvious.The particle size of the emulsion droplets observed under the microscope gradually decreased,and the particle size distribution gradually became uniform.Then SRGO-2 was used as a stabilizer and the reaction conditions was controlled,the initiator types,monomer addition methods,SRGO form,SRGO content,polymerization temperature,reaction time,oil phase type,oil-water ratio and the addition of other emulsifier 3203N affects the monomer conversion,latex particle size and emulsion stability of Pickering emulsion polymerization.Finally,the monomer conversion of the emulsion is more than 87%,and the latex particle size is about 300?400 nm.(3)The application of acrylate copolymer Pickering emulsion in coatings.Adding additives to the obtained acrylate copolymer Pickering emulsion to prepare coatings,and then apply different types and contents of SRGO coatings on tinplate to make coatings.The coatings are tested through dielectric resistance and electrochemical experiments.The anticorrosion performance of the layer is investigated.It is found that the coating with 0.2wt%SRGO-2 has the best anti-corrosion performance,with water resistance up to 12 d and salt water resistance up to 6 d.And the test results of electrochemical experiments verify that the coating containing 0.2wt%SRGO-2 has the best anti-corrosion performance.