The Design of Functional Ion Gels and Hydrogels for Additive Manufacturing of Devices and Composites

Abstract

Additive manufacturing (AM or 3D printing) involves selective deposition of materials in a layer-by-layer fashion to create customizable structures with precise 3-dimensional control. As AM evolved from a rapid prototyping process to a key driver towards the next industrial revolution, massive efforts have been made towards developing advanced printable materials. However, significant progress is still required to be made to push AM materials toward greater accessibility of the technology and functionality of the materials. One promising method to achieve this goal is 4D printing (4DP), which involves AM of materials that change their material properties (post-printing) in response to an external environmental stimulus. Stimuli-responsive materials have seen increased utility in AM of tissue engineering models, biomedical application, sensory and actuating devices. This thesis focuses on the development of stimuli-responsive hydrogels, ion gels, and ionoelastomers, for direct-ink-write (DIW) printing of composites, sensors, and actuators. Chapter 1 includes an overview of current stimuli-responsive materials for AM and their applications. Chapter 2 discusses the first demonstration of DIW printing of ion gel without the need of curing between layers or use of a nonsolvent, and 3D printing of soft sensors that have increased stretchability through both the material’s mechanical properties and the structural auxetic design. Chapter 3 explores incorporation of polymerizable ionic liquids to print shape memory ionoelastomers that can exhibit multi-directional bending upon stretch and release of the printed structure. Chapter 4 introduces a new method of post-print photocuring opaque hydrogel/particle composites via triplet fusion upconversion to overcome the limitations posed by traditional UV curing.