A Comparative Study Of 8-Hydroxyquinoline Aluminum/Conductive Polymer Core-Shell Composite

Conductive polymer polypyrrole and polyaniline have become one of the most widely used materials because of their good environmental stability,ease of synthesis,and good electrical conductivity.However,conductive polymers have poor flexibility and poor processability.8-hydroxyquinoline aluminum(Alq3)has been shown to be one of the most promising materials for the fabrication of organic light-emitting devices.This material exhibits many features similar to inorganic semiconductors such as relative stability,easy synthesis,good electron transport and lights emitting.However,organic light-emitting devices based on Alq3 show quite low stability due to the effects of environment aging and photo-oxidation.Therefore,how to improve the stability of 8-hydroxyquinoline aluminum and the processing properties of conductive polymers have become the focus of current research.We considered using microemulsion polymerization to synthesize core-shell composites in order to improve the stability and processability of composite materials.The use of conductive polymers as "shells" and 8-hydroxyquinoline aluminum as a "core" for composites not only combines the advantages of 8-hydroxyquinoline aluminum with conductive polymers,but also improves their overall performance because of the interaction of two substances.The main results are as follows:(1)Preparation of conductive polymer.Polypyrrole was prepared by chemical oxidation polymerization method using water as the reaction medium.The effects of dopants,reaction time,reaction temperature,oxidant species,and oxidant-monomer molar ratio on the molecular structure,microstructure,and phase type of the polymer were investigated using an orthogonal test.The Fourier transform infrared spectroscopy(FT-IR),scanning electron microscopy(SEM),X-ray diffraction(XRD),and resistance tests were used to characterize and analyze the optimal reaction.Conductive polyaniline was prepared using similar experimental procedures with hydrochloric acid as a doping agent and ammonium persulfate as a initiator,which paves the way for later comparative studies.(2)Preparation of 8-hydroxyquinoline aluminum/polypyrrole core-shell composites.8-hydroxyquinoline aluminum/polypyrrole core-shell composites were prepared via in situ chemical oxidative polymerization with ammonium persulfate as an oxidizer and HCl as a dopant.The Alq3,PPy,and Alq3/PPy composite were characterized using XRD,FTIR,SEM,and thermo-gravimetric analysis(TGA).XRD was used to analyze the crystallization properties of the composites;FTIR was used to characterize the special chemical bonds in all the materials;the morphology and structural characteristics of the composites were characterized by SEM.This article also tested the electrical conductivity of composites.Furthermore,the possible formation mechanism of Alq3/PPy core-shell structure composites were also demonstrated.(3)Preparation of 8-hydroxyquinoline aluminum/conductive polymer core-shell composites.AIq3/PPy and Alq3/PANI core-shell composites were prepared by the same experimental scheme as above using sodium dodecylbenzenesulfonate as a dopant and ammonium persulfate as an initiator.The molar ratio of sodium dodecylbenzenesulfonate-pyrrole(aniline)and ammonium persulfate-pyrrole(aniline)was changed,and the influence of the relative content of dopants and initiators on the chemical structure,surface morphology,and electrical conductivity of the composites was investigated.Finally,the reaction speed,structure morphology and material properties of Alq3/PPy and Alq3/PANI core-shell composites were compared.