Study On The Preparation And Corrosion Resistance Of Polypyrrole And Its Derivatives/SiO₂ Composites

Polypyrrole(PPy)and its derivatives have drawn much attention due to their good mechanical and physical properties,non-toxicity,chemical stability and high catalytic activity.It not noly has excellent optical and electrical properties,widely used in sensors,electronic materials and biomedical fields,but also has a little corrosion resistance,used to prepare organic composite coating,which is expected to replace the current galvanized passivation process,to achieve green coating technology.However,there are some problems of a single PPy and its derivatives such as insoluble,easily reunion,poor dispersion,low corrosion resistance and so on,so this study improves its dispersion and corrosion resistance by doping nanoparticles PPy and its derivatives compound modification.This thesis explores the preparation conditions of nano-SiO2,and obtains the best preparation process.The synthesis of PPy,PPy/nSiO2,PNMPy,PPy/PNMPy,PNMPy/nSiO2 and PPy/PNMPy/nSiO2 materials were carried out respectively,and samples were characterized by XRD,FT-IR and SEM.The results showed that PPy/nSiO2,PNMPy/nSiO2 and PPy/PNMPy/nSiO2 composites were successfully prepared.The corresponding composite coating materials were prepared and the performance analysis was carried out.The electrochemical data of different coatings were tested in different immersion time.The results are as follows:(1)The addition of PPy/nSiO2 to polyurethane can significantly improve the corrosion resistance of the coating,and the corrosion resistance of the coating is obviously better than that of the zinc coating.The corrosion resistance of 4%-PPy/nSiO2/PU coating is the strongest.(2)The corrosion resistance of PPy/PNMPy/nSiO2/PU and PNMPy/nSiO2/PU coatings doped with SiO2 is obviously better than that of undoped coating materials,PPy/PNMPy/nSiO2/PU has the best corrosion resistance among them.(3)The protection efficiency PE of 4%-PPy/nSiO2/PU coating for 240 days was 92.78%,12.60%higher than the undoped coating,52.74%higher than the single PU coating,84.67%higher than the zinc coating.It turns out that PPy/nSiO2/PU coating material has a long time corrosion resistance.(4)The anti-corrosion properties of PPy/PNMPy/nSiO2/PU and PNMPy/nSiO2/PU coatings for 240 days were studied respectively,PE was found to be 95.23%and 92.96%,respectively,11.97%and 13.56%higher than that of the undoped SiO2 coatling,indicating that the corrosion resistance of the coating material doped with SiO2 is stronger.(5)Methyl-substituted coating materials have higher conductivity and reactivity,resulting in higher potential difference and more excellent corrosion resistance.It turns out that PPy/PNMPy/nSiO2/PU is the most corrosion-resistant material in the coatings studied.