Electronic Theses and Dissertations

Juan Chen

Date

2022

Document Type

Dissertation

Degree Name

Doctor of Philosophy

Department

Physics

Committee Chair

Chenhui Peng

Committee Member

Firouzeh Sabri

Committee Member

Mohamed Laradji

Committee Member

Erno Istvan Lindner

Committee Member

Omar Skalli

Abstract

Programming shape changes in soft materials require precise control in directionality and magnitude of their mechanical response. Among ordered soft materials, liquid crystal elastomers (LCEs) exhibit remarkable and programmable shape-shifting when their molecular order changes. In this dissertation, we proposed a new method to fabricate complex spatially-varying ordered LCEs by a maskless projection display system. By programming the synchronization of the rotated polarizer and projected segments with different shapes, various configurations of topological defects ranging from single to two-dimensional lattice of arbitrary patterns are created in a deterministic manner. We synthesized, remotely programmed, and modeled the reversible and complex morphing in the monolithic LCE kirigami encoded with predesigned director fields. We obtained a rich variety of out-of-plane shape transformations including auxetic structures and undulating morphologies by combining different topological structures and kirigami geometries. The spatiotemporal shape-shifting behaviors are well recapitulated by elastodynamics simulations, revealing that the complex shape changes arise from integrating the custom-cut geometry with local director profiles defined by topological defects inscribed in the material. Different functionalities such as fluttering of the Chinese crane bird “QianZhiHe”, arbitrary directional locomotion in an annulus ring, linear locomotion in the complex Chinese character, bio-inspired fluttering butterfly, flower bud, dual-rotation light-mill, and dual-mode locomotion are further realized. Our proposed LCE kirigami with topological patterns opens opportunities for future developments of multi-functional devices for soft-robotics, flexible electronics, and biomedicine. Nanofiber arrays with a complex organization can be produced by using our new proposed fabrication techniques. Oriented arrays of nanofibers are ubiquitous in nature and have been widely used in the re-creation of biological functions such as bone and muscle tissue regenerations. The nanofiber arrays can effectively guide and promote neurite outgrowth. The applications of nanofiber with arced profiles and topological defects on neural tissue organization are also demonstrated. This finding, combined with the versatility and programmability of nanofiber structures, suggests that they will help solve challenges in nerve repair, neural regeneration, and other related tissue engineering fields.

Comments

Data is provided by the student

Library Comment

Dissertation or thesis originally submitted to ProQuest.

Notes

Embargoed until 1/12/2023

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