Functional Microperiodic Polyacrylamide Gels Fabricated by Opal Inversion and Direct-Write Processes
Barry, Robert Angus, III
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https://hdl.handle.net/2142/72162
Description
Title
Functional Microperiodic Polyacrylamide Gels Fabricated by Opal Inversion and Direct-Write Processes
Author(s)
Barry, Robert Angus, III
Issue Date
2008
Doctoral Committee Chair(s)
Wiltzius, Pierre
Department of Study
Materials Science and Engineering
Discipline
Materials Science and Engineering
Degree Granting Institution
University of Illinois at Urbana-Champaign
Degree Name
Ph.D.
Degree Level
Dissertation
Keyword(s)
Engineering, Materials Science
Abstract
Functional three-dimensional microperiodic polyacrylamide hydrogel structures were created and characterized. Submicron to 50 micron periodicities were explored across the structures, the lower end for optical and filtration potential and the larger for cell growth scaffolds. Two synthesis methods were employed; inversion of self-assembled monodisperse colloidal crystals which yields an inverted FCC lattice of polymer, and direct ink writing (DIW) in which a continuous filament is patterned layer-by-layer into a defined structure.
Inverse opal (IO) structures were tested as non-aqueous humidity sensors. Due to the size of the structure periodicity, visible Bragg reflection changed with swelling in the hydrogel lattice. Rapid kinetics of water absorption by the hydrogel film and reflection change sensitive to ambient humidity were observed.
Similar IO structures were imparted chemical sensitivity by active groups designed to control swelling within the structure. Swelling of the hydrogel causes pressure and distortion within the structure, impinging on the permeating porous network. We examined potential tunable filtration by changing the pore size as a function of hydrogel response. However, several manufacturing and fundamental obstacles prevented successful tuning of filtration. We analyze the failure mechanisms and presented solutions for improved materials and methods in future work.
Elastomeric polyacrylamide (PAM) ink for use in a DIW process was developed and characterized. The ink is designed to crosslink by UV exposure during patterning and maintains its elastomeric quality afterwards. Patterning mechanisms were adapted to this ink and the optimization process is explored for continuing ink development to encourage the creation of additional elastomeric inks.
Scaffolds patterned by DIW were tested as growth templates for 3T3 fibroblast cells. Gradient structures were created to examine cell preference for a range of shapes and spacing. Results of cell viability were analyzed and cell behavior on the structure is observed. Cells were found to integrate into the scaffold and larger spacing was preferred. The reasoning behind several modifications made to the patterning process to better accommodate cell growth and potential improvements for future work are discussed.
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