09/21/17 -9:45 AM to 11:00 AM
Student Seminar Series: Professor Timothy E. Long
Student Seminar Series
"Designing functional polymers for 3D printing: From material extrusion of ion-containing polymers to stereolithography of multifunctional acrylates"
Additive manufacturing, or 3D printing, revolutionizes the fabrication of unique and complex architectures in a layer-by-layer approach. In concert with engineering innovation, design and synthesis of novel polymers is crucial for the development of these technologies beyond their current limitations. A unique synthetic strategy involving simultaneous photo-polymerization and crosslinking of acrylate systems during vat photo-polymerization printing overcomes traditional material challenges associated with the technique. This novel approach combines processing advantages of low molecular weight systems with tunable (thermo) mechanical performance similar to high molecular weight polymer networks. Additionally, unrivaled fabrication of polyimide structures with micron-scale resolution is possible through solvent-based vat-photo polymerization printing. Synthesis of poly(amic diethyl acrylate ester) as novel photo-crosslinkable precursors enables printing of novel 3D organogels. After thermal treatment, these objects isotropically shrink and imidize to produce high-resolution thermoplastic polyimide objects.
Ion-containing polymers introduce unique functionality and processing advantages to 3D printing. Targeted material design provides novel poly(ether ester) ionomers suitable for fused deposition modeling (FDM) additive manufacturing. Standard synthesis through melt polymerization of poly(ethylene glycol) and sulfonated isophthalate produces a printable, water-soluble ionomer. Ion exchange to divalent counter-ions such as calcium, magnesium, and zinc provides a high degree of tunability in melt viscosity. Poly(ether esters) ionomers with calcium counterions yielded flexible filmanent for subsequent processing and printing. Increased processability from ion interactions and tuned viscosity enables unprecedented FDM printing below 80 °C.
Professor Long received his bachelor’s degree in chemistry from St. Bonaventure University, followed by his doctorate in chemistry from Virginia Tech. He spent nearly a decade as a research scientist at Eastman Kodak Co. and Eastman Chemical Co. before returning to Virginia Tech as a professor in the Department of Chemistry.
He has more than 45 patents in the field of macromolecular science and engineering, and has recently exceeded 230 peer-reviewed publications. He has been a faculty member in the Department of Chemistry since 1999, and currently serves as the director of the Macromolecules Innovation Institute at Virginia Tech.
He has received many prestigious honors in his field of polymer chemistry recently, including the 2015 Virginia Scientist of the Year, American Chemical Society (ACS)PMSE Cooperative Research Award, and ACS POLY Mark Scholars Award as well as the Pressure Sensitive Tape Council Carl Dahlquist Award in 2011, Virginia Tech’s Alumni Award for Research Excellence in 2010, 2009 ACS Fellow, and invited organizer of the Gordon Research Conference—Polymers, and Chair, ACS Polymer Division. He serves currently as the Vice-President of the Adhesion Society for 2016-18, and was recently elected as an AAAS Fellow.
Professor Long maintains a vigorous partnership with diverse industries, including BASF, Elevance, Michelin, SABIC, ExxonMobil, Procter & Gamble, IBM, 3M, Kimberly Clark, Henkel, Bayer, Kraton Polymers, Toray, and Solvay. He has maintained a 20-member interdisciplinary research group and has been awarded ~ $43M in research funding over the past 16 years at Virginia Tech.
His continuing research goal is to integrate fundamental research in novel macromolecular structure and polymerization processes with the development of high performance macromolecules for advanced technologies, including additive manufacturing (3D printing), drug and gene delivery, sustainable feedstocks, adhesives and elastomers, engineering polymers, block copolymers and living polymerization, and biomaterials for health and energy.