Study on patterning processes and supercapacitors using dually responsive materials and electrodeposition

Abstract

In this thesis, a combination of top-down lithography and bottom-up electrochemical deposition was presented to implement novel organic/inorganic structures and applications were studied supercapacitors. First, new UV curable binder polymers having photoreactive methacrylate moiety were designed and synthesized by grafting GMA to carboxylic acid groups on MAA of copolymer. Novel synthesized polymer had excellent thermal behavior and high transmittance at 365 nm. In addition, we could successfully obtain photolithographic patterns with low swelling, high sensitivity, and high resolution dry film photoresist (DFR). In a second phase, Universal templates with a high aspect ratio nanopore array were developed using a bilayer system of a silicon-containing block copolymer top layer and a dually responsive photoresist bottom layer. The dually responsive photoresist cross-links upon heating and degrades upon exposure to UV light. Therefore, the template can be easily removed by dipping in an aqueous base solution. Moreover, gold and polypyrrole nanostructure arrays were fabricated by electrodeposition and a simple removal process of the template. To expand applicable area of gold nanostructure, nanoporous gold from electrodeposited AuAg alloy was fabricated and investigated as 3D current collector for $Ni(OH)_2$ supercapacitor. The capacitance was optimized by considering the amount of $Ni(OH)_2$ in two different regions, the inner pores and the top of the NPG electrode. We have developed an outstanding supercapacitor with high capacitance, high energy density, and semi-permanent lifetime using the $Ni(OH)_2$/NPG electrode.