Preparation And Performance Of Conducting PEDOT/PI Films By Depositing Polymerization Of EDOT On Hydrolyzed PI In Liquid Phase

Poly(3,4-ethylenedioxythiophene)(PEDOT) film may exhibit excellent electricalconductivity, optical transparence and environmental stability. PEDOT films can be used fornot only antistatic coatings but also electrodes in organic light emitting diodes, electrochromicdevices, transparent electrode, flexible display devices and so on. Fabricating PEDOT filmsbecomes a hot topic in polymer science and many scientists have devoted to this topic. Theinvestigated methods to fabricate PEDOT films include physical coating, physical depositing,electrochemical polymerization and oxidative polymerization in-situ. Of them oxidativepolymerization in-situ seems to be more attractive.In this thesis, the wettability and adsorbing capacity of polyimide (PI) film wereimproved by alkaline hydrolysis. The hydrolyzed PI film was immersed in FeCl3solution toadsorb FeCl3. The PI films with adsorbed FeCl3were suspended in EDOT solution to cultureconducting PEDOT. The changes of functional groups on the PI film were characterized withATR-FTIR and XPS spectrometer; the surface resistance was measured with Keithley2635ASource Meter in four-probe mode.To enhance the uniformity and thickness of the PEDOT layers synthesized in situ on PIfilm, hydrolyzed PI films were oxidized in H2O2solutions and then adsorbed FeCl3fromFeCl3solution. The PI film with macromolecular peroxides and FeCl3were suspended inEDOT solution to culture conducting PEDOT films. The amount of peroxides on PI film wereanalyzed with ATR-FTIR、XPS and wet chemicals; the wettability and adsorbing capacitywere investigated with contact angle and weighting analysis; the surface resistance ofPEDOT/PI composite films were measured; the thickness of PEDOT film was determinedwith AFM. The doping level of the obtained PEDOT film was analyzed with XPS. Thefactors that affected the adsorption capacity of PI film and the surface resistance ofPEDOT/PI composite film were discussed. Finally, the feasibility to fabricate FCCL andHDI-FPC with the depositing polymerization of EDOT on PI film was investigated.The alkaline solutions promoted the hydrolysis of imides rings in PI molecular chains and introduced amic acid groups onto PI surface, hence, enhanced the hydrophilicity andadsorbing capacity of the PI film. The adsorption of FeCl3increased from0.89to1.44g/m2.The adsorbed FeCl3catalyzed the polymerization of EDOT on PI surface in EDOT solution;the absorption bond of S-H stretching appeared on ATR-FTIR spectrum of the PI film and theS signal appeared on the surveying XPS spectra after suspending in EDOT solution; thesurface resistance of the obtained PEDOT/PI composite films were as low as105Ω. ThePEDOT films were about90nm thick and the doping level was about18.5%.Peroxide acid group was identified on the surface of PI film after the film soaked withH2O2solutions and the content of peroxide groups was measured as high as5mmol/m2. Theperoxides promoted the chemical oxidative polymerization of EDOT with FeCl3on PI surface.With the aid of the dual oxidants, the surface resistance of PI film droped to103Ω aftersuspending in EDOT solution. The thickness of the obtained PEDOT film was measured to beabout150nm and the doping level was about30%. Copper wire patterns could be fabricatedon the surface of PEDOT/PI film by electrical plating after the PEDOT was exposed to172nmVUV radiation through masks.