Abstract
This study investigates the synthesis of high molecular weight poly(hexaphenyl-m,p-quaterphenylene) via a catalyst-free Diels-Alder reaction, and its subsequent membrane physical aging effects were studied to assess property changes with time.
The polymer was synthesized in air with a high degree of molecular control, evident from a 36% para to 64% meta backbone ratio, contributing to its distinctive mechanical and chemical properties. Films solution-cast from the synthesized polymer demonstrate exceptional durability and toughness, essential for robust ion exchange membranes in harsh environmental conditions. Long-term aging studies on the glassy poly(phenylene) (PP) films reveal a decline in gas permeability and fractional free volume (FFV). These material changes increased gas selectivity due to densification effects below its high glass transition temperature (Tg ~ 390 °C). Material aging dynamics are critical for applications in gas separation technologies, where membrane stability directly influences operational lifespan and efficiency.
Our findings highlight that while the synthesized PP offers excellent initial thermochemical stability and mechanical properties favorable for membrane technologies, aging-induced physical property changes require strategic considerations. Addressing these aging effects can lead to developing more durable, high-performance membranes, crucial for sustainable energy applications such as carbon capture, hydrogen production, and advanced battery technologies.
This study seeks to advance the fundamental understanding of PP’s application potential and sets the stage for future research into optimizing other polymer formulations to help mitigate aging effects while maximizing performance.
Bio
Chris Cornelius, Ph.D.
Department Chair, Materials Science and Engineering
Iowa State University
Dr. Chris Cornelius is the Endowed Department Chair in Materials Science and Engineering at Iowa State University. His career blends materials science with real-world applications.
Before academia, he worked as a Research Engineer at Dow Plastics, developing metallocene-based polyolefins and elastomers, managed a multimillion-dollar respirator mask production line at 3M, and served as a staff scientist at Sandia National Laboratories, focusing on ionomers, fuel cells, and gas separation materials. His research explores the relationships between structure, properties, transport, and function in materials, including synthetic and charged polymers, hybrid materials, and sol-gel-derived glasses, covering synthesis to processing into nanocomposites and nanofibers.
He is an editor for the Journal of Materials Science, actively promoting the publication of high-quality research spanning polymeric to composite materials. His career showcases an interdisciplinary commitment to scientific advancement and social impact. From his non-academia beginnings to his current role as Department Chair, he continually seeks to bridge fundamental research and practical application.