%0 PDF %T A Micromolding-based Evaporation-Polymerization Technique for Rapid and Tunable Fabrication of Hydrogel Films Containing Micropatterned Opal Structures %A Bukenya, Maurice. %D 2018-10-09T07:38:27.197-04:00 %8 2018-10-09 %R http://localhost/files/fq978645r %X Abstract: Opal-structured thin-film hydrogel materials hold great potential for utility in a wide range of sensing applications. However, it remains significantly challenging to synthesize these films in a rapid, inexpensive and reliable manner. Prevailing techniques especially suffer from long opal deposition times, and often tend to involve complex and relatively expensive steps. In this thesis, I examined a reliable, rapid and inexpensive micromolding-based evaporation-polymerization method for fabricating poly (ethylene glycol)-based opal-structured thin films. Specifically, intense, highly uniform opalescent colors were achieved by filling microwells in a PDMS mold with Polystyrene (PS) bead solution and allowing the liquid in the bead solution to evaporate in a controlled manner so that the PS beads were arranged into a Face-centered cubic (FCC) structure. Then, upon drying, the interstitial spaces of the packed structure were filled with a UV-curable poly(ethylene glycol) diacrylate (PEGDA) prepolymer solution. The prepolymer solution was polymerized under UV light and the opal-containing PEG films recovered by peeling them off from the mold. Opal deposition using my evaporation-aided technique reduces deposition time to 30-45 minutes only. In addition, the as-prepared films show high tunability of opal color by simply changing PEGDA content in the prepolymer solution. Swelling and de-swelling studies show highly reversible and tunable responsiveness of the films to wetness, pointing to potential applications in humidity sensing. Finally, SEM images confirm the preservation of the FCC structure of the opals in these films.; Thesis (M.S.)--Tufts University, 2018.; Submitted to the Dept. of Chemical and Biological Engineering.; Advisor: Hyunmin Yi.; Committee: Ayse Asatekin, and Qiaobing Xu.; Keywords: Nanotechnology, Materials Science, and Chemical engineering. %[ 2022-10-12 %9 Text %~ Tufts Digital Library %W Institution