Title

In situ Polymerization of Conjugated Polymers and All-Organic Electrochromic Fabrics

Date of Completion

January 2011

Keywords

Chemistry, Polymer|Textile Technology

Degree

Ph.D.

Abstract

Conjugated polymers have been widely utilized in applications such as electrochromic devices, organic photovoltaics, smart windows, organic transistors etc. Their unique electric properties and the ability to reversibly change color under external electrical stimuli, combined with their low cost, high coloration efficiency and versatile structures make them ideal candidates for the aforementioned applications. However, the processability issue faced by many conjugated polymers, along with the inefficient traditional assembly approach, greatly limited the use of some readily available conjugate polymer materials. We have found a simple yet efficient alternative assembling method in which monomers were mixed with polymer electrolyte before converted to their polymer forms. This novel approach, termed "in situ assembly", is applicable to any monomer that can be dissolved in the electrolyte solution, less sensitive to the polymerization environment, and can reduce assembling time and cost without sacrificing device quality and stability. The device fabrication, polymerization kinetics and mechanism were discussed in Chapter 3. Furthermore, because polymerization takes place after the device assembly, it offers a unique platform for studies that cannot be performed in traditional methods. For example, a high through-put copolymer selection model based on this platform was discussed in Chapter 4. The fundamental of diffusion of small molecules in solid state electrolyte matrix was used as a way to determine how monomer feed ratio affects the resulting copolymer properties. Copolymers of two or more monomers with various ratios can be obtained and characterized in a single run. This method can precisely identify the feed ratio needed to achieve a specific desired color, and could be extended to any other applications that require customized copolymer compositions. ^ We have also extended electrochromic studies onto a spandex fabric substrate. Spandex was impregnated with PEDOT-PSS, a conjugated polymer complex dispersed in water, in order to achieve a conductive fabric. The resulted fabric has a reasonable conductivity and retained the stretchability of the spandex as investigated. This unique substrate is the base of a stretchable color-changing fabric device. By studying the electrical properties of the spandex fabric, the performance of electrochromic material on the substrates as well as assembled devices were investigated in Chapter 5 and Chapter 6. Chapter 7 introduced the development of a break-through stretchable polymer electrolyte. With this electrolyte we have achieved all the key factors that could are essential for making the "truly wearable displays". ^