Preparation And Application Of Dispersible And Highly Conductive Carbon Dot Polyaniline Composite

Polyaniline,as a polymer with unique conductive properties,has attracted much attention because it is often used as anti-corrosive filler.However,due to the strong interaction between its chains,its solubility or dispersibility is poor,which greatly limits its application.In order to significantly improve the dispersibility of polyaniline in solvents without affecting its conductivity,a method of inducing polyaniline nanocomposites using carbon dots as template was proposed in this paper.The modified polyaniline nano composite material has the characteristics of small size,good dispersibility,good conductivity compared with the unmodified polyaniline,and the like,which is more beneficial to improving the anticorrosion performance of the modified polyaniline nano composite material.In this paper,the modified nano polyaniline was added into acrylic resin to prepare the coating,and the anticorrosion and antifouling properties of the coating were studied.The fluorine-containing nano-SiO₂was prepared by sol-gel method and introduced into the modified polyaniline acrylic resin coating,and its anticorrosion and antifouling properties were studied and compared.The carbon sites with chitosan,ethylenediaminetetraacetic acid,citric acid,and metformin hydrochloride as precursors,designated as CTS-CDs,EDTA-CDs,CA-CDs and N-CDs,were prepared by top-down method.Polyaniline（PANI）and polyaniline nanocomposites（CDs/PANI）were synthesized by the polymerization of aniline at room temperature using ammonium persulfate as the initiator.The results showed that the introduction of N-CDs into the polymerization of aniline significantly improved the dispersion stability of product PANI.With the increase of the introduction of N-CDs,the dispersibility of N-CDs/PANI was gradually improved.Besides,the introduction of a certain amount of N-CDs not only does not affect the conductivity of PANI,but also significantly increases the conductivity of PANI from 198.7 S/m to 413.6 S/m.This is because,on the one hand,CDs surface has a large number of sp²clusters,which can form a conjugated structure with PANI;On the other hand,the nitrogen atom in N-CDs can form a special luminescence trap to attract electrons to flow in.However,due to the redox property of the carbon sites,excessive N-CDs content will quench the free radicals,resulting in the decrease of the molecular weight of PANI,and further reducing the conductivity of PANI.In view of the excellent dispersibility and high conductivity of polyaniline nanocomposites（N-CDs/PANI）,it was introduced into acrylic resin as a filler to obtain a coating with both outstanding anti-corrosion and anti-fouling properties.The surface morphology of that pure acrylic resin coat,the acrylic resin coating with PANI as a fill and the acrylic resin coating with N-CDs/PANI as a filler are analyzed,and the N-CDs/PANI is easy to disperse in the acrylic resin to form a compact structure,increase the contact point with a metal substrate,promote the formation of a passivation layer and enhance the obstruction to a corrosion medium;The effect of that amount of N-CDs/PANI introduce on the adhesion,coating hardness and corrosion resistance of the N-CDs/PANI/acrylic resin coat was studied by adding different contents of N-CDs/PANI filler in the acrylic resin.when the content of N--CDs/PANI is less than 8wt%,the adhesion grade is 5A and the coating hardness decreases with the increase of filler content.According to EIS test,when the introduction amount of N-CDs/PANI is 4wt%,the corrosion resistance of the acrylic resin coating is optimal,and the value of|Z|_0.01is the highest,about 1.32×10⁷Ωcm².Compared with the|Z|_0.01（1.17×10⁴Ωcm²）of the PANI acrylic resin coating,it is increased by three orders of magnitude,and compared with the|Z|_0.01（20.32Ωcm²）of the bare steel sheet,it is increased by six orders of magnitude.And by Tafel curve test,the coating at this time has the highest corrosion potential and the lowest corrosion current,anticorrosive performance is excellent.After soaking in 1.2 M hydrochloric acid solution for ten days,the surface of the steel sheet coated with 4wt%acrylic resin coating still has the metallic luster;The antifouling test of pure acrylic resin coating,PANI acrylic resin coating and N-CDs/PANI acrylic resin coating was conducted.The results showed that the algae inhibition rate of N-CDs/PANI acrylic resin coating reached 24.6%due to the redox property of PANI and the bactericidal property of N-CDs.The micro-nano rough structure on the surface of the N-CDs/PANI acrylic resin coating is constructed by nano-SiO₂particles,and the antifouling ability of the coating is further improved by realizing the hydrophobic and super-hydrophobic properties of the coating surface.Nano-SiO₂and fluorine atom-modified nano-SiO₂were prepared by sol-gel method using tetraethyl orthosilicate and fluorine-containing silane（FS-1）as precursors,respectively.The influence of the content ratio of F-SiO₂and SiO₂on the static contact angle of water phase on the surface of the coating was studied.the results showed that when the total mass of added SiO₂and F-SiO₂accounted for 60%of the resin and the mass ratio of SiO₂and F-SiO₂was 7:2,the coating had the maximum contact angle of 148.75°and the hydrophobic property was the best.With the optimal conditions fixed,the effects of the amount of N-CDs/PANI（1%,2%,4%and 8%of the total mass of the resin）on the static contact angle of the water phase and the adhesion of the coating were tested.The results showed that,although the hydrophobicity of the obtained composite acrylic resin coating was the highest with the contact angle of 152.6°when the introduction amount of N-CDs/PANI was 1wt%,in combination with the anticorrosion and antifouling performance test,the optimal introduction amount of N-CDs/PANI was 2wt%.Under this condition,the contact angle of the hydrophobic coating of the composite acrylic resin was 142.81°and|Z|_0.01was 4.73×10⁵Ωcm².In particular,the algae inhibition rate was increased by three times as compared with that of the non-hydrophobically modified N-CDs/PANI acrylic resin coating,reaching 98.5%.