Designing Advanced Macromolecules for Advanced Manufacturing: Balancing Reactivity, Rheology, and Resolution*

Additive manufacturing (AM) offers the promise for addressing looming concerns for materials sustainability with chemical processes that require less energy and result in less material consumption. However, research must impose a lens of sustainability earlier in the innovation process, where processes and materials are designed to adhere to the principles of green chemistry and strive for more sustainable engineering. Novel materials for AM continue to emerge at a feverish rate, and it is imperative that we begin to consider end-of-life (EOL) earlier in the material and process design. Our research has focused on light-based AM modalities due to the unique combination of low energy consumption, exceptional resolution that enables less material consumption in latticed architectures, and the opportunity to print high molecular weight polymers with low viscosities. An important motivation is the opportunity to intensify chemical processes, wherein the synthetic chemistry occurs in a printed shape that serves as the reactor that ultimately results in a printed object. Advanced macromolecular materials for advanced manufacturing require a precisely tailored balance of reactivity and rheological performance that collectively ensure precise resolution from diverse additive manufacturing modalities. This lecture will exemplify our most recent efforts involving vat photopolymerization of fully aromatic polyimide hydrogels for printing carbonaceous objects, aqueous polymeric latexes for printing ABA triblock copolymer elastomers, and printing unsaturated polyesters in the absence of solvent with the opportunity for subsequent recycling. Polyimide polymeric salts offer desirable solution viscosity, and recent efforts have involved the tuning of crosslink density with mixed polysalts wherein the photo-active diacid concentration is precisely controlled.  Sulfonation of diamines renders all-aromatic polyimide precursors in water, thus enabling the vat photopolymerization of polyimides in water.  SIS triblock copolymers are prepared as a colloid and printed in the presence of an aqueous scaffold.  Removal of water allows for the formation of nanostructured ABA triblock copolymers with tensile elongations exceeding 800%.