Fabrication And Application Of Polypyrrole And Its Composites

Polypyrrole(PPy)is regarded as one of the most attractive materials due to not only its high conductivity,good biocompatibility,simple synthesis methods but also its excellent environmental and thermal stability.It has wide applications in the fields such as energy storage equipment(lithium-ion batteries and super capacitors),adsorption materials,chemical sensors,biosensors,pressure sensors,various biomedical devices,biological materials,preservative coating and other fields.In general,electrochemical and chemical oxidative polymerization are the most important methods for preparing polypyrrole.Although each method has its own advantages,there are still some shortcomings in the actual synthesis and application process,shch as an electrochemically synthesized PPy is low molecular weight and low preparation efficiency and the yield and conductivity of polypyrrole are affected by many factors through chemical methods.Besides,it's also difficult to complex with other materials to achieve better performance.In order to solve these problems,a large number of researchers explore the improvement of polypyrrole synthesis methods,which has become a hotspot during the last few years.Herein,we have concentrated on two aspects in this paper.On the one hand,we study and improve a new method for the preparation of polypyrrole.On the other hand,we prepared polypyrrole composites through reasonable design and synthesis route.In this paper,polypyrrole and its composites with different morphology and excellent properties were prepared by using different oxidizing agents to meet the demands in different fields.The main contents and achievements of this thesis are as follows:1.The monodispersed PPy nanoparticles were prepared simply through the ?-ray radiation first in the air-saturated strong acidic aqueous solution of Py.The formation of PPy nanoparticles is related with the strong oxidative atmosphere in the air-saturated strong acidic solution under the irradiation of ?-ray.As a result,the polymerization of the dissolved Py monomers is readily initiated and high-molecular-weight PPy macromolecules are rapidly produced and then isolated from water in the form of nanoparticles due to their poor water solubility.The prepared PPy nanoparticles exhibited significant NIR(808 nm)photothermal conversion efficiency(40.1%).The MTT assay and fluorescence staining assay indicated that the PPy nanoparticles also have low toxicity.The in vitro and in vivo experiments indicated that the prepared PPy nanoparticles also exhibited enough strong NIR photothermal effect in cells to ablate tumor cells effectively.This work offers a green and convenient synthesis strategy for PPy nanoparticles,which is great potential to provide one of high-efficient photothermal agents for cancer therapy.2.The monodispersed raspberry-like hollow-structured PPy microspheres(H-PPy)were successfully prepared through the in-situ growth of PPy nanoparticles on PS template microspheres,followed by the etching of PS template with THF.When the H-PPy microspheres were dispersed in aqueous solution and irradiated by NIR laser(808 nm),they showed significant photothermal conversion effect,and excellent photostability.(S)-(+)-camptothecin(CPT)can be conveniently loaded through a simple dispersion-permeation method,with a load capacity of 0.14 mg/(mg H-PPy).The MTT assay and the in vitro NIR-laser triggered release behavior indicated that the pure H-PPy microspheres have good biosafety,but the release of loaded CPT in H-PPy microsphere can be achieved with remarkable spatial/temporal resolution after NIR laser irradiation,which results in the excellent synergistic effect of photothermal and chemical ablation of HeLa cells.The high drug-loading capacity and efficient NIR light photothermal effect,as well as the convenient synthesis route,make the raspberry H-PPy microspheres potential to be a promising cancer therapy agent.3.The rGO/PPy composite hydrogel was synthesized by the redox reaction between GO and Py in the isopropanol aqueous solution(10%).In the course of the reaction,the Py monomer acts as a reducing agent for GO reduction,and GO acts as an oxidizing agent for pyrrole polymerization.The formation of complex hydrogels is due to the self-assembly processes due to the reduction of hydrophilic GO into hydrophobic rGOs and the strong ?-? interaction between PPy and rGO.The rGO/PPy composite hydrogels exhibit excellent electrochemical properties such as high specific capacity,excellent magnification performance and excellent cycling stability.This work provides a new method for the preparation of polypyrrole composite hydrogel material.4.Yolk-shell MnO2@PPy composite microspheres were facily prepared by using yolk-shell MnO2,which obtained by oxidizing MnCO3 with KMnO4,as template and initiator.The introduction of polypyrrole improves the electrical conductivity of the material,and this unique yolk-shell structure can also effectively reduce internal stress caused by the volume expansion-shrinkage,which protect the electrode from physical damage caused by high-speed charge and discharge process.The electrochemical test results show that the yolk-shell MnO2@PPy composite microspheres have excellent electrochemical properties such as high specific capacity,outstanding magnification performance and cycling stability.This work provides a new method for improving the electrical conductivity,structural stability and cyclic stability of the material.