SEMINAR: Tailoring Polymer Structure for Additive Manufacturing...02-11-2020

Speaker:  Prof. Timothy Long

Title: Tailoring Polymer Structure for Additive Manufacturing: From Vat Photopolymerization of Elastomers to Binder Jetting Pharmaceuticals

Date/Time: 4 November 2020/ 17:00 - 18:00 

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Abstract:Covalent and non-covalent (physical) networks continue to receive significant attention with particular focus on tailoring highly efficient chemical pathways for crosslinking and tuning crosslink density to optimize mechanical performance of high performance thermosets. Sustainable chemistry together with green chemistry continue to provide an overarching motivation for our discovery of advanced materials and advanced manufacturing, addressing end-of-product-life challenges for polymeric products with a circular economy paradigm. This lecture will highlight recent advances in polymer design with a molecule to manufacturing perspective, and crosslinking plays a major role in the design of elastomers for 3D stereolithographic printing, polyimides for vat photopolymerization, and novel polymer architectures for binder jetting of water-soluble adhesives. Star-shaped architectures of water soluble poly(N-vinyl pyrrolidone) allow high concentrations for jetting solutions into powder beds for pharmaceutical manufacturing. The star-shaped polymers, which are prepared using RAFT polymerization, result in reduced entanglement concentrations, and higher c* concentrations that permit a higher maximum jetting concentration. Photo-reactive, fully aromatic polyimides that are decorated with acrylate substituents provide chemically crosslinked organogels that are amenable to thermal post-processing, and thermal decomposition of the network scaffold occurs without structural detriment to the polyimides. Our latest efforts involve the preparation of semi-interpenetrating networks of latexes and crosslinked functional poly(ether) scaffolds using vat photopolymerization (see adjacent figure). Recent efforts have demonstrated three-dimensional elastomeric objects that approach the performance of conventional elastomers in the presence and absence of the scaffold network. This lecture will illustrate various crosslinking strategies where the crosslinks are susceptible to reversibility using various external stimuli, ranging from heat and pH to photo-irradiation and ionic salts.

Bio: Tim received his Ph.D. in Chemistry from Virginia Tech under the direction of Prof. James McGrath, and he subsequently joined both Eastman Kodak and Eastman Chemical companies for eight years upon graduation.  He joined the faculty in the Department of Chemistry at Virginia Tech, where he also served as the Director of the Macromolecules Innovation Institute until 2019.  In 2020, Prof. Long accepted an interdisciplinary faculty position across the School of Molecular Sciences (SMS) and the School for Engineering Matter, Transport, and Energy (SEMTE) at Arizona State University (ASU) where he will launch and lead the Biodesign Center for Sustainable Macromolecular Materials and Manufacturing (BCSM3). In addition to over 400 peer-reviewed  publications, his research awards include the 2020 Virginia Outstanding Faculty Award, 2015 Virginia Scientist of the Year, 2010 Virginia Tech Alumni Research Award, ACS PMSE Collaborative Research Award, PSTC Carl Dahlquist Award, 2019 ACS Rubber Division Thermoplastic Elastomer Award, and the ACS POLY Mark Scholar Award. He has served as the Chair of the ACS Division of Polymer Chemistry, Chair of the Gordon Research Conference in Polymers, 2012 Chair of the IUPAC World Polymer Congress, and he currently serves as the Past-President of the Adhesion Society.  He is a member of advisory boards for leading journals, and he was recently appointed as Editor-in-Chief of Wiley Polymer International.