Confining The Polymerization Of Aniline And Investigating The Properties Of Product

Polyaniline ?PANI? nanomaterial is one kind of conductive polymers with good properties such as unique doping mechanism, reversibility of redox. thermal conversion and so on. As a result, the application prospects of PANI are very broad. Different structures of PANI nanoparticles have been synthesized so far. among which yolk-shell nanostructure has been paid much attention. It takes more advantage of the cavity between the core and shell. Giving full play to the role of the cavity can expand the application field of PANI. In addition, PANI can also be used as the precursor of nitrogen doped carbon ?NCs? materials when it is calcined under the condition of high temperature and the atmosphere of nitrogen or inert gas. In this way, some certain structure of NCs can be prepared. NCs as one kind of nonmetal catalytic materials have attracted more attention, especially the excellent performance in the electro-catalysis for cathode oxygen reduction reaction ?ORR? of fuel cell. In this paper, we have realized the polymerization of aniline in a confined space by using the sacrifice template method, which led to the formation of PANI@SiO₂. On one hand, based on the photothermal conversion properties, PANI@SiO₂ is used for drug loading and photothermal release; On the other hand, it is used as the precursor to synthesize NCs which have good electro-catalytic activity. The main contents of this paper are as follows:1. The polymerization of aniline was realized in a confined space by using CeO₂ nanoparticles as reactive templates that were encapsulated by SiO₂. The weak solubility of CeO:in acidic solution, resulting in the slow release of Ce4+ ions with a high oxidizing potential. Meanwhile, the porous structure of the SiO₂ shell allowed an equilibrium to be established between the diffusion of aniline inward and Ce4+ ions outward from the shell, which realized the polymerization of aniline in the cavity. The influences of the shell thickness, reaction temperature and aniline concentration on the generation of the yolk-shell nanostructures were investigated in detail. By virtue of the excellent photothermal property of polyaniline that was confined in the SiO₂ shell, the product was applied in drug loading and photothermal releasing using 5-fluorouracil as a representative anticancer drug.2. PANI confined in the SiO₂ shell was pyrolyzed and carbonized at high temperature. The product was further disposed with concentrated alkaline solutions via hydrothermal process to remove the SiO₂ shell and formed nitrogen doped carbon nanoparticles ?C-NCNP?. During the experiment, we explored the effect of different calcination temperature on the performance of the product. The synthesized C-NCNP was applied to the electrocatalysis for ORR. It was found that 900 ? was the optimal temperature and the corresponding product labeled as C-NCNP-900 showed the perfect performance. As a controlled experiment, we synthesized PANI in the absence of SiO₂ protection under otherwise the same conditions followed by calcination at 900 ? to get NCNP-900, which exhibited worse ORR performance than C-NCNP-900.