Synthesis And Properties Of High-Performance Conducting Polypyrrole In A Functional Medium

Conducting Polymers (CPs) have been used in many fields because of their good performances, while the medium used in polymerization or redox process plays a key role. In this thesis, a new multi-functional (oxidizing, magnetic and hydrophobic) ionic liquid (IL), 1-butyl-3-methylimidazolium tetrachloroferrate (BMIM[FeCl4]) was used as the new medium to synthesize conducting polypyrroles (PPy), which is totally different from the conventional organic solvents or inert ionic liquid. Chemical and electrochemical polymerizations of pyrrole, and redox test of PPy were carried out in the neat BMIM[FeCl4] or its solutions with various solvents. The present work not only exploits the application of functional IL in CPs, but also supplies a new outlook in developing new functional CPs. The main results acquired in this thesis are described in detail as follows,Firstly, a simple chemical method was raised to recover BMIM[Fecl4] from its aqueous homogeneous mixture with H2O via a two-step way by adding some inorganic salts. Compared with the previously reported method, this method overcomes the limitation that BMIM[FeCl4] can only be separated from a two-phase solution containing over 20%(v/v) BMIM[FeCl4].In fact, with this method BMIM[FeCl4] was successfully recovered from its homogeneous aqueous solution containing only 1%(v/v) BMIM[FeCl4].Secondly, in order to increase the yield and the rate of reaction between Py and BMIM[FeCl4], chemical and electrochemical polymerizations of monomer pyrrole in pure IL BMIM[FeCl4] and in various solution were systematically studied, and the effects of adding solvents on the PPy were discussed. Results show that all the solvents can be divided into three categories in terms of their effects on pyrrole polymerization:strongly enhancing, enhancing and inhibiting. Based on the thermodynamics and kinetics analysis, these different effects were well explained. Results of the Cyclic Voltammetry (CV) measurements demonstrated that these chemically polymerized PPy have good electrochemical behaviours. In addition, PPy films electrochemically synthesized in the same solution medium had a loose structure and high electrochemical activity; as well as exhibited hydrophility.Thirdly, PPy thin films with fine nano-structures were obtained by an interfacial polymerisation at the interface of (pyrrole aqueous)/(BMIM[FeCl4]). It was found that the ferromagnetic susceptibility at room temperature was 8.0 emu/g which was five times as high as that reported in references. This magnetic film was also electrochemical active. This result maybe paves a way towards the potential application for micro-wave absorbant materials or electrical-magnetic shields.Fourthly, PPy gel was obtained by a direct chemical polymerization of pyrrole monomer and BMIM[FeCl4]. Carbon fiber, carbon nanotubes, carbon aerogels were introduced in the PPy gel in the polymerization process to improve its electrochemical activity and mechanical performance. On the other hand, three dimension networks PPy/PAA hydrogel were obtained using PAA as the first and second network and PPy as the third network. The effects of the mole ratio of MBAA to PPA on the mechanical and electrochemical activity behavior were investigated.