具熱可交聯性、彈性與高疏水性之PEDOT:PSS導電複合薄膜：製備、性質分析及應用

Abstract

Poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) conductive film exhibits excellent conductivity and transparency so that it could be applied in various fields, such as antistatic coatings, optoelectronic displays, and solar cells. However, the water resistivity, weather stability, and fragile property of PEDOT:PSS film limit its development. In this research, a series of approaches by introducing thermally curable monomer, soft latex, and inorganic silica nanoparticles were employed to effectively improve the weather stability, elasticity, flexibility and hydrophobic property of PEDOT:PSS conductive film. In the first part (Chapter 2), P(SS-NMA) was copolymerized by thermally curable monomer N-(methylol acrylamide) (NMA) and 4-styrenesulfonate (SSNa) in water. The gel content, moisture absorptivity, and swelling index were used to evaluate the properties of P(SS-NMA) copolymer. Then, P(SS-NMA) copolymer was regarded as a template to prepare PEDOT:P(SS-NMA) dispersion. The optoelectronic properties and surface morphology of the PEDOT:P(SS-NMA) thin film were investigated. The thermally curable PEDOT:P(SS-NMA) conductive film possessed better weather stability and water resistivity than PEDOT:P(SS) conductive film did. In the second part, two approaches were adopted to enhance the film’s elasticity and flexibility. In Chapter 3, poly(butyl acrylate-styrene) (P(BA-St)) soft latex with low glass transition temperature (Tg) was synthesized by using different ionic charge types of surfactant. The P(BA-St) soft latex was blended with PEDOT:PSS dispersion to prepare a series of PEDOT:PSS/P(BA-St) conductive thin films and elastic conductive thick films. The PEDOT:PSS/P(BA-St) conductive thick film exhibited 97 % of elongation and 30 S/cm of conductivity with good weather stability. In Chapter 4, the core-shell PSS-PBA soft latex was also carried out by using PSS as a polymeric surfactant in the polymerization of butyl acrylate (BA). Transmission electron microscopy (TEM) and zeta-sizer were employed to investigate the size and morphology of PSS-PBA soft latex. Then, the PSS-PBA soft latex was used as a template in the oxidative polymerization of EDOT. The optoelectronic properties and surface morphology of the resulting PEDOT:PSS-PBA conductive thin films were characterized. During the bending and weather stability test, the PEDOT:PSS-PBA conductive thin film exhibited better flexibility (R/R0 < 1.2) and hydrophobic property (contact angle = 75°) than PEDOT:PSS film did (R/R0 = 1.5, contact angle = 40°). In the third part (Chapter 5), the hydrophobic property of the PEDOT:PSS film was improved by introducing fluorine-modified silica nanoparticles. The fluorine-modified silica with various particle sizes was prepared via sol-gel process. By either blending or coating approach, PEDOT:PSS/fluorine-modified silica conductive film exhibited high water contact angle (contact angle > 90°) and good weather stability. Also, the optoelectronic properties and surface morphology of the conductive thin films were characterized. In Chapter 6, a modeling program was developed to calculate the contact angle in the stripe, grid point, and diagonal point patterns as well as a composite film with roughness. Minimum convergent volume (MCV) was specified to obtain an appropriate water drop volume to measure the contact angle. Furthermore, the contact angle of hydrophobic PEDOT:PSS/fluorine-modified silica conductive film was calculated by the program to compare with the experimental measurement. For bending method, a particle restriction supposition was presented. For coating method, different wetting states resulted from the different particle sizes on the surface. Finally, in Chapter 7, PEDOT:PSS was applied as the anode material in the field of electroluminescent devices. Via introducing water soluble polymer poly(vinyl pyrrolidone) (PVP), the PEDOT:PSS/PVP conductive dispersion could effectively increase its viscosity and wetting property on the resin. After coating the dielectric resin, fluorescent layer and PEDOT:PSS/PVP dispersion on the template orderly, the electroluminescent devices could be demonstrated.