Preparation Of Structurally And Mechanically Functional Coatings Based On Conducting Polymer PEDOTs And Their Electrical Applications

Intrinsically conductive polymers（ICPs）are now a rapidly growing field in material science due to their important scientific research value and promising commercialapplications.AmongthefamilyofICPs,poly（3,4-ethylenedioxythiophene）（PEDOT）and its derivatives（PEDOTs）are among the star materials due to their excellent environmental stability,high doped state conductivity and permeability,good redox activity and cycle life,and have been widely studied in the fields of antistatic,electrochromic,supercapacitors,thermoelectric devices,solar cells,etc.Poly（3,4-ethylenedioxythiophene）:polystyrene sulfonate（PEDOT:PSS）is used in a wide range of applications such as new-generation flexible displays,high-performance electrolytic capacitors,antistatic coatings,electrically protective and shielding layers,organic light-emitting diodes（OLEDs）,printed electronics,and many others,owning to its excellent aqueous processing properties.Heraeus has a monopoly in PEDOT:PSS with its Clevios?product line.However,commercially available products such as PH 1000 are expensive,and the resulting films have poor structural and mechanical properties（pencil hardness,adhesion,etc.）and high moisture absorption,limiting their application in the field of conductive coatings.In order to overcome these problems,this thesis firstly prepared PEDOT:PSS aqueous dispersion,and then combined it with waterborne epoxy system（including epoxy emulsion and petrified epoxy curing agent or bio-based epoxy curing agent）,silane coupling agent,nano-fillers,etc.,to explore the electrical,mechanical,surface and interface,water resistance and other properties of the prepared PEDOTs（PEDOT and PEDOT:PSS）-based conductive coatings under different composition and proportioning conditions,in order to obtain conductive coatings with excellent structural and mechanical properties and water resistance in a cost-effective way.The specific studies are as follows:1.PEDOT:PSS aqueous dispersion was synthesized from3,4-ethylenedioxythiophene（EDOT）monomer by a simple and efficient chemical oxidation polymerization method,and then combined with waterborne epoxy system,and further introduced organic-inorganic caged polysesquioxane（POSS）,silane coupling agent（SCA）,etc.The structural morphology,mechanical and electrical conductivity,surface wettability,water resistance,etc.of the coatings were systematically investigated.Specifically,a series of PEDOT:PSS/Epoxy（A）composite coatings with different solid ratios were prepared by mixing the self-made PEDOT:PSS aqueous dispersion with the pre-dispersed waterborne epoxy emulsion A/curing agent A by mechanical co-blending.Then,the two ratios with better antistatic properties were selected,and POSS and SCA were further introduced by using the orthogonal method to investigate their effect on the structural morphology,electrical,interfacial,mechanical,water resistance and other properties of PEDOT:PSS/Epoxy（A）/POSS/SCA composite coating.Finally,the coatings with a pencil hardness level of HB,adhesion force of level 1 and volume resistivity applicable to antistatic utilization were obtained.2.In view of the Ultraviolet（UV）resistance of epoxy components and the complex regulation of quaternary system,the silane coupling agent KH560 modified with nano-Si O₂（KH560/Si O₂）was introduced into the mixture of PEDOT:PSS and waterborne epoxy emulsion B/bio-based curing agent B to prepare PEDOT:PSS/Epoxy（B）/（KH560/Si O₂）ternary composite system.And the mechanical and electrical properties,water and UV resistance of the coatings were investigated.By using inexpensive KH560/Si O₂filler,the amount of film-forming compound was further reduced and the pencil hardness level and UV resistance of the coatings were further enhanced,while the bulk resistance was only slightly increased.3.In order to further simplify the preparation process,the PEDOT:PSS/Epoxy（B）dispersion was prepared by the one-pot method of oxidative polymerization of EDOT monomer in the presence of waterborne epoxy emulsion B.The mechanical and electrical properties,water resistance of the composite coating formed after the dispersion was dried and cured alone and the PEDOT:PSS/Epoxy（B）dispersion formed with the curing agent/different solvents were explored separately.Of them,the coatings using dimethyl sulfoxide as the dilution solvent for the curing agent exhibited higher pencil hardness level（2H）and adhesion force（level 2）as well as lower bulk resistance.