Synthesis And Electromagnetic Shielding Performance Of The Nano-polyaniline Interface Research

In this paper, It was reviewed the history of polyaniline's evolution, especially its synthesis method and the polymerization mechanism. The structure of polyaniline, the doping mechanism were summarized, too. The effects of reactional condition on the properties of polyaniline were analyzed by the numbers. It was studied the synthesis method of nanofibers polyaniline (PANI) by interfacial polymerization, and characterized their properties through four-probe method, FTIR, UV-Vis, XRD, TGA,SEM etc techniques. It was explored the relationship between the conductivity and the parameters of synthesis technology and also investigated the Shielding Effectiveness (SE) of PANI which were synthesized in different reactive medium such as n-butyl alcohol/water, ethanol/water or n-hexyl alcohol/water by interfacial polymerization. The main results are summarized as follows:(1) By orthogoral experiments, condition of basic synthetic technology for producing PANI was made as follows: the stirring rate; stirring time; HCl doping time and vacuum drying time, respectively. It was also researched the elements'effect on the conductivity of PANI such as the amount of organic solvent in reaction system of organic solvent/water; HCl acid concentration; the molar ratio of oxidant to monomer (aniline). A better synthetic technology for producing PANI whose conductivity was 3.55 S·cm^-1.(2) The diameters of polyaniline(PANI) nano-fiber which was synthesized through interfacial polymerization by optimum techonolgy were about 60-100 nm and the lengths of these were from 600nm to several microns.(3) FTIR spectra of PANI synthesized in aqueous n-butyl alcohol, ethanol or n-hexyl alcohol showed the relationship between oxidized repeat unit of PANI and its conductivity. UV-vis spectra of these showed that ABS₁/ABS₂ of PANI closed to EB at n-butyl alcohol/water system. After the investigation of the crystalline structure of PANI synthesized in different aqueous solvents it was found that the crystalline structures were affected by the organic solvents in the reactive medium. The thermal gravimetric analysis (TGA) of PANI was studied and the results showed that it was accorded with one-dimension model for PANI synthesized in aqueous solvents.(4) The tests were made on the Shielding Effectiveness (SE) of PANI which were synthesized in three kinds of reaction medium, respectively. The results showed that the higher conductivity of PANI, the better SE of the overall trend. The values of SE reached more than 40dB from 150 kHz to 3GHz, and overreached the standard of the general industrial or commercial use of electronic devices. Compared with n-hexyl alcohol/water, ethnol/water reaction medium, the SE parameters of PANI nanofibers synthesized in n-butyl alcohol/water reaction medium showed the best tendency, thereinto the highest value was 79.1dB.