Study On The Preparation And Properties Of Polyaniline And Its Derivative Doped With Calcium Lignosulphonate

As a kind of new functional polymer materials, PANI has become one of thehottest focuses in the polymer area due to its unique and excellent performance.However its applications are limited as it is infusible and insoluble in most solvents.Calcium lignosulphonate (LGS), a cheap by-product of pulp processing industry, whichcontains a lot of activity groups such as sulfo group in its molecular structure, can beused to dope PANI for the improving of solubility and electrical conductivity etc.However, there exist great steric hindrance between the polymeric sulfonate and theconducting polymer during the polymerization, which can cause the torsion of the PANIbackbone, thus making it difficult for the effective doping of LGS into the PANI chains.Chemical reactions with free radicals are dramatically affected by the magnetic fieldand the important magnetic field effect on most organic polymer molecules is magneticorientation. Uniform magnetic field tends to align molecules more neatly and orderly inthe polymerizing medium, which can indeed greatly improve the dope degree and canbe favorable for the increasing conductivity, solubility and thermal stability of thereaction products. In this paper, the conductive PANI-LGS with high solubility wasfirstly prepared by emulsion polymerization method in the presence of magnetic field(0.4T). The effect of reaction time, concentration of LGS, HCl and APS on the redoxperformance and conductivity of PANI-LGS are studied by cyclic voltammetry andstandard four-probe method. The effects of magnetic field on the polymerizationbehavior, orientation of the structure and performance of the PANI-LGS is investigatedby viscosity test, electrical conductivity test, solubility test, cyclic voltammograms andimpedance spectroscopy, FT-IR,XRD, thermogravimetric analysis and SEM.The results indicated that the optimal properties of PANI-LGS were achieved whenthe mass fraction of LGS was8.5%, the reaction time was5h, the molar ratio of HCl toAn was5:1, the molar ratio of APS to An was1:1. Compared with the product preparedwithout the magnetic field, the conductivity of the PANI-LGS synthesized in thepresence of magnetic field (0.4T) increased by more than four times. Meanwhile, thesolubility of the PANI-LGS was rather excellent in NMP, dimethyl sulfoxide organicsolvents etc.Poly (2,3-dimethyl aniline)(P (2,3-DMA), as one of the electron-substitutedderivatives of aniline, has significant anticorrosion property. Nowadays, the demands for production efficiency and environmental benefits are increasing fast, so seeking forthe technique which is efficient, energy saving and less environment pollution has beenan important research direction. LGS contains various active groups, which endow itwith good dispersing and wettability performance. In this paper, LGS is added into thepolymerization system of2,3-DMA to prepare P (2,3-DMA)/LGS (PDL)．The effects ofLGS content, the concentration of APS and H3PO4, the reaction time, the reactiontemperature on the tafel, EIS curves and yield of PDL are discussed, the structure andproperties of PDL were also investigated using FTIR, XRD, SEM, solubility andaccelerated corrosion test.When mass ratio of LGS was25%, nH3PO4/n2,3-DMA=2.5:1, nAPS/n2,3-DMA=2:1, t=10h,T=30°C, the anticorrosion performance and yield of PDL were the highest. FT-IRindicated that PDL has been synthesized successfully. The performance of P (2,3-DMA)or PDL as protective coating against corrosion of steel was assessed by immersion testin3.5%NaCl. Compared with P (2,3-DMA)/PVA coating, the PDL/PVA coatingexhibited superior corrosion protection for the steel. On one hand, the introduction ofLGS into P (2,3-DMA) could reduce the cost and is beneficial for environmentalprotection, on the other hand, the solubility, dispersion and anticorrosive performanceof P (2,3-DMA) were greatly improved.