Abstract
At present, the self-doped polyaniline bear sulfonic, boronic and carboxylic groups, but bearing phosphonic group is rare in the study. The phosphonic acid functional group as the protonic acid radical of the self-doped polyanilines, it does not only show enough acidity for doping but also is a dibasic acid. The first acid radical is used to internal-doping in the polyaniline backbone, and the second acid radical would provide features, such as forming salt while keeping the doping state. In 2014, the Japanese study teams reported the studies of the self-doped polyaniline bearing phosphonic acid. The materials they used in the subsequent analysis showed good thermal stability, high transparency, polaron delocalization and self-doped effects. But there are not perfect studies in bearing phosphonic acid polyaniline area, therefore, there is still looking forward to improving performance and developing usability in the future. In this study, we try to use bearing phosphonic acid aniline (3-aminophenyl phosphonic acid) as the monomer and use the chemical oxidative polymerization with the various experimental parameters. Then, analyze the surface morphology, molecular structure, redox level and protonation level. Proved via UV-visible spectra and FTIR spectra, poly(3-aminophenyl) phosphonic acid similar to polyaniline backbone. The polymers can form the porous structure in the morphology by adding the initiator. For the proton exchange materials, increasing the surface area can effectively increase the proton transfer pathways. In addition, adding the initiator increase the degree of spins delocalization and protonation level effectively. The degree of protonation level increased from 20.26-37.64 (%) to 44.04-72.37 (%) (The oxidant is APS), 12.34-14.43 (%) increased to 14.05-19.35 (%) (The oxidant is K2S2O8) and 1.60-16.02 (%) increased to 10.57-30.26 (%) (The oxidant is H2O2). The redox level of the poly(3-aminophenyl phosphonic acid) can be controlled by the choice of oxidant. When using K2S2O8 as the oxidant, the average redox level is about 1.54, that is a relatively high level of oxidation. Whereas H2O2 is about 0.61, that is a high level of reduction. However, regardless of which oxidant is used, the polymers all have -N+- protonated structures, the binding energy ~401eV. Finally, the experiment progress found that poly3-aminophenyl phosphonic acid has spins delocalization effect. When using AP as the initiator, the A/B ratio tends to 1 have an optimum spin symmetry and a high degree of electron delocalization. Poly(3-aminophenyl phosphonic acid) is non-conductive, due to the acid group of the chemical structure has an interaction with the polyaniline backbone. Based on the current experimental results, poly(3-aminophenyl phosphonic acid) is a porous material that does not have electron conductivity. It can be known from the literatures that the phosphonic acid functional group can serve as the proton-donating and proton-accepting, so the polymer is proton conductivity. Therefore, it is expected to become a proton exchange material or an organic spintronic material.