Synthesis And Properties Of Graphene Oxide Modified Acrylic Emulsion And Its Coatings

Since its discovery,graphene has attracted great attention in the material field due to its unique excellent properties.Graphene oxide,a derivative of graphene,also has good mechanical properties,acid resistance,alkali resistance,thermal properties,optical properties and barrier properties.In addition,oxygen-containing functional groups(hydroxyl,carboxyl,epoxy,etc.)on the surface of the graphene oxide film provide the reaction sites needed for modification.At the same time,due to the low price and simple preparation,graphene oxide has been widely used in the research of composite materials in recent years,which also involves the field of coating resin.As the requirements of environmental protection become higher and higher,waterborne coatings develop rapidly.At present,the research on the application of graphene oxide to waterborne coatings has become a hot topic.But most of them are based on physical blending.And among them,the research on the water-based acrylic resin coating is relatively short.This study broke through the limitations of the traditional physical modification by finding and adopting a method of chemical modification,which had successfully used graphene oxide for modifying the acrylic resin emulsion by means of covalent bonding.At the same time,the properties of the GO-modified acrylic emulsion coatings were studied.It was found that the properties of the GO-modified acrylic emulsion coatings were significantly improved,such as acid and alkali resistance and salt spray resistance.The specific innovations as follows:1.Compared with the pure acrylic emulsion coating,the time of acid and alkali resistance of the coating in which the intermediate GOMI-HEA added is increased.The time to the addition of the intermediate is linear growth,which respectively are 1h,2h,3h,4h,5h.Moreover,the corrosion resistance time reaches 5h,which is five times of the pure acrylic emulsion coating,as the addition of GOMI-HEA is further increased to 20wt%.2.Compared with the pure acrylic emulsion coating,as the addition of the intermediate GOMI-HEA is increased to 17.08wt%,the coating has the longest salt spray corrosion time,which reaches 48 h,and it was four times that of the pure acrylic emulsion coating.After experiment for 196 h at the same time,the coating sample in which 17.08wt% GOMI-HEA added has the minimum corrosion condition,and its coating film is the most complete.In this paper,firstly the graphite oxide was prepared by Hummers method,and then it was separated by ultrasonic oscillation to produce graphene oxide(GO).The chemical structure of GO was analyzed by Fourier transform infrared spectrometer(FTIR).Through the characteristic peaks of oxygen-containing functional groups(hydroxyl,carboxyl and epoxy groups),it is proved that GO is prepared successfully by Hummers method.Then,isopolone diisocyanate(IPDI)was semi-closed by hydroxyethyl acrylate(HEA),thereby obtaining the product called as HI.The surface modification of graphene oxide was carried out by reaction on the isocyanate(-NCO)of HI and the hydroxyl(-OH)of graphene oxide,thereby obtaining the modified GO called as HIGO.The chemical structure of HIGO was characterized by FT-IR,and the characteristic peaks of the functional groups such as carbamate,methyl,methylene and carbon-carbon double bond are found.The structure of GO and HIGO was characterized by X-ray diffractometer(XRD),and results show that : GO: 2?=12°;HIGO: 2?=9°.Thermogravimetric analyzer(TG)shows that: the thermal stability of HIGO is improved compared with GO,and a characteristic peak presented the thermal decomposition of the carbamate occurs at 250 ? ~ 330 ?.The surface morphology of GO and HIGO was observed by scanning electron scanning microscope(SEM),and it is found that the layer spacing of HIGO is larger after modification,even one or fewer layers are observed.All characterization methods illustrate the successful modification of graphene oxide.And HI was successfully grafted to GO by using covalent bond,which verified the feasibility of this method.Afterwards,according above methods,using IPDI as the connecting bridge,the GO modified intermediate called as GOMI-HEA was prepared,which introduced GO to HEA through covalent bond.Then,as a modifier,GOMI-HEA was introduced into the mixed system of acrylic acid(ester)monomer according to certain proportion of material,and a series of acrylic emulsion modified by GO was synthesized by coreshell emulsion polymerization.The chemical structure of the intermediate products and emulsion was characterized by FT-IR,and the results demonstrate that the GO modified acrylic emulsion is successfully obtained.Finally,the acrylic emulsion was prepared into a coating and coated.And the effect of the different addition of GOMI-HEA on the film performance was investigated.The results show that when the addition of GOMIHEA is 17.08%,the comprehensive performance of the coating is the best: hardness reaches H,adhesion reaches level 0,impact resistance increases by 10 kg.cm,wear resistance increases by 1 time,acid resistance and alkali resistance increases by 4 times,and corrosion resistance is the best.