Controllable Syntheses And Performance Studies Of Conducting Polymer Based Aerogels

This dissertation focuses on structure-controlled syntheses and performance studies of the conducting polymer aerogels and their composite aerogels. On the basis of conducting polymers, assisted by graphene oxide obtained by modified Hummer’ method, self-crosslinked polyaniline aerogel, polypyrrole/grapheme/Ag NWs composite aerogels and polyaniline-polypyrrole nano-hollow spheres(PHS)/graphene composite aerogels were prepared, as well as their physicochemical properties and practical performances have been characterized in detail.Self-crosslinked polyaniline aerogels have been successfully synthesized via oxidative coupling reaction in the absence of any additional crosslinkers only by using ammonium persulfate as oxidizing agent and aniline hydrochloric salt as precursor. The morphology, micro-structure, specific surface area etc. of the as-prepared aerogels have been investigated by SEM, TEM, XRD, Raman, and N2 adsorption-desorption tests. It turned out that the origins of self-crosslink are:(1) ortho-position of the aniline could react with monomer to generate branched chains, and probably produced another polyaniline chains to obtain network structure;(2) π–π stacking of benzene rings could also link different chains to get mesh structure, and(3) physical entanglement of long chains could also enhance the network. The results of stress-strain measurement showed the as-prepared aerogel have a certain mechanical properties. When used as electrode materials of supercapacitor, the polyaniline hydrogel manifested a higher specific capacitance: 750 F/g at current density of 1 A/g.By using graphene oxide as crosslinkers, polyaniline-polypyrrole nano-hollow spheres(PHS)/graphene composite hydrogels have been synthesized by uniformly mixing PHS and graphene oxide, ascorbic acid reduction. Then by supercritical carbon dioxide drying, heat-treated under 900 ℃ for 10 h and so on, carbon nano-hollow spheres(CHS)/graphene composite aerogels obtained. The microstructure, morphology, and specific surface area etc. of the as-prepared composite aerogels have been investigated by a series of characterization methods. Results have indicated that the as-prepared composite aerogels have superior mechanical strength with Young’s modulus as high as 1.83 MPa. Electrochemical results have indicated that the CHS/graphene composite aerogels have a higher specific capacitance(226.5 F/g at a current density of 0.1 A/g) than that of pure graphene and carbon aerogels.Graphene oxide was used as surfactant to mix Ag NWs, and then taking advantage of the spontaneous assembly between graphene oxide and pyrrole, polypyrrole/graphene/Ag NWs composite hydrogels have been successfully prepared. Supercritical carbon dioxide drying and heat-treated at 180℃ for 2 h were used to obtain the corresponding aerogels, which possessed surface area(774.5 m2/g) and electrical conductivity(15.4 S/m). SEM, TEM and N2 adsorption-desorption tests were used to investigate the morphology and porous structure of the resulting composite aerogels. When used as electrode materials of thermocells, the as-prepared composite aerogels manifested a certain electric energy output: the normalized current density is 0.375 A/m2*k, normalized power density is 0.121 A/m2* k and the relative efficiency of energy conversion is 0.08%.