Department of Chemistry Seminar – Prof. Jinwen Zhang
About the event
Speaker: Prof. Jinwen Zhang
Host: Prof. Jack Zhang
Title: Catalyst-free Transesterification-enabled Epoxy Vitrimer Systems and Potential Applications
Abstract:
Thermosetting polymers are widely used in coatings, adhesives and structural composites due to their excellent thermal stability, mechanical properties, and chemical resistance. However, their permanently crosslinked network structures prevent reprocessing and limit chemical recyclability. Recent research has focused on incorporating dynamic covalent chemistry to impart malleability and chemical recyclability. Among various dynamic covalent linkages, ester bonds are particularly attractive because they are already intrinsic to many commercial thermosets and chemically versatile, making transesterification-enabled covalent adaptable network (CAN or vitrimers) especially promising.
Most reported epoxy vitrimers rely on high loadings of Lewis acids or strong organic bases as catalysts -which often lead to poor miscibility and are toxic and costly. To address these drawbacks, we aim to develop catalyst-free vitrimerization strategies that can be seamlessly integrated into existing epoxy resin systems without disrupting industrial practice.
Conventional epoxy-anhydride curing forms esters but no hydroxyls, while epoxy-amine curing generates hydroxyls but no esters – each missing a key component for transesterification. We designed two complementary solutions: (1) incorporating polyhydric compounds into epoxy-anhydride systems to maintain hydroxyl availability in the system, and (2) adding glycidyl ester comonomers to epoxy-amine systems to introduce ester links.
The polyhydric additive initiates ester formation and regenerate hydroxyl groups through a self-catalytic sequence, maintaining constant hydroxyl concentration. These hydroxyls, when presented at significant levels, catalyze transesterification, enabling dynamic network rearrangement. In the epoxy-amine system, glycidyl ester comonomers similarly yield networks rich in ester links and hydroxyl groups, which are sufficient to drive vitrimer behavior.
These modified epoxy systems demonstrate excellent performance as composite matrices and coatings. By simple and practical formulation changes, conventional epoxy resins can achieve vitrimeric adaptability and improved chemical recyclability without altering industrial processing. These approaches are broadly applicable to both commercial petroleum-based and biobased epoxies, offering a scalable pathway toward recyclable thermosets with robust properties.
Biography:
Dr. Jinwen Zhang is a professor in the School of Mechanical and Materials Engineering at Washington State University. He is an expert in sustainable polymer materials, with nearly 30 years of research experience in synthesis of biobased polymers, recyclable thermosets, and chemical recycling of plastic and composite waste. His work has led to innovative and practical solutions for advancing circular materials and polymer sustainability. Dr. Zhang holds 15 issued U.S. patents and 5 in pending. He has published over 147 peer-reviewed journal articles, 11 book chapters, and one edited book.
His contributions have been recognized with the James Hammar Memorial Service Award (2021) from the BioEnvironmental Polymer Society, the Gold Medal of Excellence in Government Award (2013) from the Philadelphia Federal Executive Board for his collaborative work with USDA-ERRC, the Tan Chin Tuan Exchange Fellowship in Engineering (2023) from Nanyang Technological University, and senior member of National Academy of Inventors (2024).