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Research Interests

Professor Torkelson’s group research motivation is driven by two main desires: (1) to understand at a fundamental level how molecular-scale behavior of polymers relates to macroscale properties; and (2) and to engineer and optimize those polymer properties by tuning molecular-scale responses via dynamic chemistry, nanoscale confinement, chain architecture, and novel solid-state processing, among other methods. For example, the group has recently developed three simple dynamic chemistry approaches that allow for spent thermosets or crosslinked polymers to be recycled by melt-state processing into new crosslinked polymer products with full recovery of crosslink density and associated properties.

They are also developing a deeper understanding of how nanoscale confinement of polymers in thin films or in nanocomposites can lead to major changes in properties, including glass transition temperature (which can change by 50 degrees C or more), physical aging, stiffness or modulus, and diffusion, among others. In support of our research efforts, we have developed simple non-destructive characterization tools that allow us to characterize the gradient in behavior from a free surface or substrate/nanofiller. They are also doing fundamental research to understand how polymer architecture (e.g., cyclic or ring polymers, stars, hyperbranched polymers, brushes, bottlebrushes, etc.) and copolymer structure can modify the bulk and nanoconfined behaviors of polymers. In turn, we are using that understanding to engineer materials for improved performance. Finally, they are also pursuing novel, industrially scalable solid-state processing approaches to design and produce modified polymers, polymer blends, composites, and nanocomposites that cannot be produced by conventional melt-state processing. Their process is the solid-state analog of twin-screw extrusion and allows for much greater work to be done on the polymeric materials during processing. As a result, their solid-state process achieves dispersion levels as well as chemistries that are not attainable with melt-state processing methods.

Education/Academic qualification

Chemical Engineering, PhD, University of Minnesota

… → 1983

Chemical Engineering, BS, University of Wisconsin-Madison

… → 1978

Research interests

  • Nanoscience and nanotechnology
  • Polymer science and engineering
  • Sustainability

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Grants

Research Output

  • 6 Scopus citations
  • 4 Scopus citations

    Reprocessable Polyhydroxyurethane Network Composites: Effect of Filler Surface Functionality on Cross-link Density Recovery and Stress Relaxation

    Chen, X., Li, L., Wei, T., Venerus, D. C. & Torkelson, J. M., Jan 16 2019, In : ACS Applied Materials and Interfaces. 11, 2, p. 2398-2407 10 p.

    Research output: Contribution to journalArticle

  • 16 Scopus citations
  • 6 Scopus citations