Light-Based Additive Manufacturing of Functional Gels via Thiol-ene Chemistry

Abstract

Additive manufacturing (AM) is an ever-growing field that has benefited several industrial sectors including healthcare, aerospace, dentistry, and construction. The hardware of AM has seen significant investment where there is currently a large variety of technologies, each with unique advantages for specific applications. Vat photopolymerization, one of the earliest forms of AM technology, has the specific advantage of printing small objects with high fidelity. Although the technologies for vat photopolymerization have been greatly improved from the initial invention, the chemistry available for light-based AM has mainly remained the same. This creates an opportunity for polymer scientists and engineers to develop new materials specifically designed for light-based AM. Currently, most commercial photocurable resins for vat photopolymerization are based on chain-growth polymerizations limiting the scope of possible monomers for AM. Introducing new chemistries into light-based AM could enable printing of new materials. Polymeric gels are a class of materials that have the potential for a wide range of applications such as sensors, engineered living materials, and biomedical applications. This thesis focuses on the development of ionogel and hydrogels that can be printed via thiol-ene chemistry. Chapter 1 includes an overview of vat photopolymerization, the chemistry available, and the benefits of thiol-X reactions for vat photopolymerization. Chapter 2 discusses the development of an ionic liquid resin that us curable by photobase generators that catalyze an anionic thiol-ene reaction. Chapter 3 introduces an allylated hyperbranched poly(glycerol) (HPG) and the effect of the hyperbranched structure which enables rapid photocuring at sub-stoichiometric quantities of thiol macromonomer. Chapter 4 builds on the HPG resin by exploring the capacity of the dried gels absorbing sufficient water form moisture to support microbial growth to enable minimally hydrated engineered living materials.