Study On The Surface Modification Of Polyaniline And Its Application In Anticorrosive Coating

The surface modification of polymers has received much attention, which can improve the performance of the polymer, or impart a variety of functions to a polymer and further expand its applications.Polyaniline (PANI) is one of the most important conducting polymers materials due to its good environmental stability, unique doping mechanism, excellent electrochemical properties, etc.; especially, it has drawn great attentions in the studies about anti-corrosion of metal. However, its applications have been greatly limited due to the high rigidity in the molecular chain backbone of PANI and the great interaction among molecular chains, which cause poor dissolubility and dispersibility. Therefore, surface modification of PANI is regarded as one of the most effective approaches to improve dispersibility in organic solvent and enhance the anticorrosive performance of PANI.In the present work, the dispersibility and stability of PANI in the paint was improved through surface modifying, at the same time, the composite coating of PANI with high anti-corrosion was prepared, which enhanced the useful value of PANI. This paper has discussed the following aspects:â‘ Surface Treatments of PANI was carried out in organic solvent by ultrasonic dispersion and the composite coating of PANI was prepared. The effect of PANI content on anti-corrosion property of composite coating was investigated by Tafel polarization curve. The results showed that when the content of PANI was 3 %( mass fraction), the anti-corrosion property of composite coating was better in 3.5 %( mass fraction) NaCl solution. In addition, the results showed that the anti-corrosion property of emeraldine base (EB) surpassed the emeraldine salt (ES), which was proved by the results of salt spray test.â‘¡The surface of PANI was modified by using octamethylcyclotetrasiloxane (D₄) and vinyl trimethoxysilane (VTMS). The effects of reaction temperature, time, and the amount of monomer, etc. on the grafting yield were investigated. Besides, the structure and property of PANI before and after modifying were compared by CV, ultraviolet-visible light spectrum (UV-Vis), fourier-transform infrared spectra (FTIR), X-ray diffraction (XRD) and thermogravimetry (TGA). The results indicated that the surface of PANI was modified effectively by using D₄, and the dispersibility, dispersibility stability and anti-corrosion of PANI were enhanced significantly.