Sung Il Hwang

Faculty Mentor(s)

Dr. Matthew Smith

Document Type

Poster

Event Date

4-11-2014

Abstract

Materials that can mimic biological behavior by converting chemical energy to mechanical work under constant external conditions represent an exciting opportunity for extending traditional responsive behavior via energy harvesting and autonomous function. One such material is the self-oscillating gel which exhibits periodic swell-deswell oscillations driven by the Belousov-Zhabotinsky reaction. A key step in increasing the functionality of these materials is the ability to form arrays of individual oscillators that can behave in a cooperative fashion. To achieve this ability the gel must be patternable while maintaining enough versatility to design its polymer backbone for optimal performance (e.g. maximum swell-deswell amplitudes). To address this challenge we explored the synthesis of vinyl terminated responsive polymer grafts. By incorporating these grafts into a nonresponsive polymer backbone at sufficient concentrations and applying an appropriate stimulation, the grafts should form microdomains (physical cross links between chains), enabling printing of any desired gel pattern. Poly-N-isopropylacrylamide (PNIPAm) was chosen as a test candidate due to its extensively studied thermo-responsive behavior. PNIPAm grafts with vinyl end group were made first by adding a primary amine group at one chain end using 2-aminoethanethiol as a chain transfer reagent during radical polymerization. Then the amine end-group was replaced with a vinyl group using an amide condensation reaction. Future work will involve the incorporation of this graft into various polymer backbones and exploring techniques for chemically fixing the networks after physical gelation.

Comments

This research was supported in part by a grant to Hope College from the Howard Hughes Medical Institute through the Undergraduate Science Education Program.

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