Designing polymers for additive manufacturing
Assistant Professor, Department of Chemistry, University of Washington
Additive manufacturing (AM) has re-emerged into the spotlight in the last 5 years driven by the rapid progress in hardware and software. In contrast, many materials currently employed with these new technologies are typically off-the-shelf products that were not necessarily designed for the purpose of AM. These materials can exhibit limited processability or compatibility with AM hardware, or lack the requisite physical properties for its intended application. Thus, there is an opportunity to design and create new materials – starting at the molecular level – to meet the specifications required for printing via an AM process, but also afford new capabilities and functionality in the printed objects. Our group 3D prints soft polymeric materials such as hydrogels and ionogels by using macromolecular composition and architecture to control the viscoelastic behavior of the corresponding inks and resins. In this seminar, I will first present multi-stimuli-responsive polymeric gels designed for direct-write 3D printing. Triblock copolymers based on F127 or poly(alkyl glycidyl ethers) were developed and formulated into stimuli-responsive hydrogels that (1) underwent a reversible sol-gel transition in response to temperature, (2) exhibited shear-thinning behavior, and (3) cross-linked in the presence of UV-irradiation. These hydrogels were further used to create living materials comprised of microbial consortia. In the second part of my seminar, I will present protein-based hydrogels for laser-scanning SLA printing. The globular shape of bovine serum albumin (BSA) was ideal for the formulation of low viscosity resins. The 3D printed constructs exhibited excellent mechanical properties and feature sizes as small as 150 microns after processing. These materials are expected to be useful for the fabrication of 3D printed medical devices.
Alshakim Nelson is an Assistant Professor in the Department of Chemistry at the University of Washington. He received his PhD in organic chemistry from the University of California, Los Angeles in 2004, where he worked with Sir J. Fraser Stoddart on carbohydrate-containing polymers and macrocycles. He was then an NIH postdoctoral fellow at the California Institute of Technology working for Professor Robert Grubbs on olefin metathesis catalysts for the formation of supramolecular ensembles. Dr. Nelson joined IBM Almaden Research Center in 2005 as a Research Staff Member where he focused on the synthesis of nanomaterial building blocks that enabled large area nanomanufacturing via self-assembly. In 2015, Dr. Nelson joined the faculty at the UW, where his research group focuses on the synthesis, characterization, and processing of stimuli-responsive hydrogels for 3D printing. Dr. Nelson has over 40 publications and 11 issued patents. His honors and awards include recognition as an IBM Master Inventor, ACS PMSE Young Investigator, Kavli Foundation Fellow, NSF CAREER award, and 3M Non-Tenured Faculty Award.