Faculty Directory
John M. Torkelson

Walter P. Murphy Professor of Chemical and Biological Engineering and Materials Science and Engineering


2220 Campus Drive
Tech E172
Evanston, IL 60208

847-491-7449Email John Torkelson


Torkelson Research Group


Chemical and Biological Engineering

Materials Science and Engineering


Ph.D., University of Minnesota

B.S., University of Wisconsin

Research Interests

Polymer science and engineering, nanoscience and nanotechnology, sustainability

We are using an environmentally benign pulverization process to achieve compatibilization of immiscible polymer blends and are investigating the molecular scale mechanisms of compatibilization. We have also shown that pulverization is useful in producing well-exfoliated polymer-clay nanocomposites.

We have developed optical sensors to characterize the glass transition temperature, gelation, and physical aging in polymers and have found great differences in behavior of nanoconfined, ultrathin films relative to bulk. We have also used single-molecule spectroscopy and simulation to follow probe diffusion in polymers, providing an explanation of how diffusion of small molecules whose motion is coupled to cooperative segmental mobility is affected by nanoscale dynamic heterogeneity. We are also developing optical sensors as pressure-sensitive paints and systems for cure monitoring.

We are achieving understanding of the role that oligomer and polymer radical diffusion plays in autoacceleration of free radical polymerization. This work, combining experiment with simulation, has also revealed the role of chain transfer reactions in mitigating reaction runaway. Controlled radical polymerization methods are also used to prepare and study a new class of polymers called gradient copolymers.

Significant Recognition

  • McCormick School of Engineering, Teacher of the Year, 2008
  • Associated Student Government Faculty Honor Roll, 2007
  • Polymer Physics Prize (awarded by the Journal of Polymer Science Part B: Polymer Physics), 2004
  • Best Paper Award, Polymer Analysis Division, Society of Plastics Engineers, 2004
  • Charles M.A. Stine Award from the Materials Engineering and Science Division of the American Institute of Chemical Engineering, 2004
  • Fellow, American Physical Society, 1999
  • Associated Student Government Faculty Honor Roll, 1995-96
  • McCormick School Advisor of the Year, 1993-94
  • NSF Presidential Young Investigator Award, 1987-92
  • Ralph A. Teetor Award (Society of Automotive Engineers), 1986
  • Lilly Foundation Teaching Fellowship, 1985-86
  • Tau Beta Pi Outstanding Teaching Award, 1984
  • Technological Institute (now McCormick School) Teacher of the Year, 1984-85

Significant Professional Service

  • Executive Committee of the Division of Polymer Physics of the American Physical Society, 2005-2008
  • Director, Materials Research Center, Northwestern University, 2003-2006
  • Caterpillar Distinguished Lecturer, Dept. of Chemical and Biochemical Engineering, University of Iowa, 2002
  • Chair, Materials Engineering and Science Division, American Institute of Chemical Engineers, 2001-02
  • Associate Dean for Graduate Studies and Research, McCormick School of Engineering, Northwestern University, 1997-2002
  • Bette and Neison Harris Professor of Teaching Excellence, 1995-98

Selected Publications

  • Soyoung Kim;John M. Torkelson, “Distribution of Glass Transition Temperatures in Free-Standing, Nanoconfined Polystyrene Films: A Test of de Gennes' Sliding Motion Mechanism”, Macromolecules, (2011)
  • Ellison, C.J.; Torkelson, J.M.; Mok, M.M., “Effect of Gradient Sequencing on Copolymer Order?Disorder Transitions: Phase Behavior of Styrene/n-Butyl Acrylate Block and Gradient Copolymers”, Macromolecules, (2011)
  • OC Compton;S Kim;C Pierre;JM Torkelson;ST Nguyen, “Crumpled Graphene Nanosheets as Highly Effective Barrier Property Enhancers”, Advanced Materials, (2010)
  • S Pujari;T Ramanathan;K Kasimatis;J Masuda;R Andrews;JM Torkelson;LC Brinson;WR Burghardt, “Preparation and Characterization of Multiwalled Carbon Nanotube Dispersions in Polypropylene: Melt Mixing Versus Solid-State Shear Pulverization (vol 47, pg 1426, 2009)”, Journal of Polymer Science Part B-Polymer Physics, (2010)
  • K Wakabayashi;PJ Brunner;J Masuda;SA Hewlett;JM Torkelson, “Polypropylene-graphite nanocomposites made by solid-state shear pulverization: Effects of significantly exfoliated, unmodified graphite content on physical, mechanical and electrical properties”, Polymer, (2010)
  • MM MOK;J KIM;SR MARROU;JM TORKELSON, “Ellipsometry measurements of glass transition breadth in bulk films of random, block, and gradient copolymers”, European Physical Journal E, (2010)
  • MM Mok;KA Masser;J Runt;JM Torkelson, “Dielectric Relaxation Spectroscopy of Gradient Copolymers and Block Copolymers: Comparison of Breadths in Relaxation Time for Systems with. Increasing Interphase”, Macromolecules, (2010)
  • S KIM;MK MUNDRA;CB ROTH;JM TORKELSON, “Suppression of the T-g-Nanoconfinement Effect in Thin Poly(vinyl acetate) Films by Sorbed Water”, Macromolecules, (2010)
  • S KIM;SA HEWLETT;CB ROTH;JM TORKELSON, “Confinement effects on glass transition temperature, transition breadth, and expansivity: Comparison of ellipsometry and fluorescence measurements on polystyrene films”, European Physical Journal E, (2009)
  • MM MOK;J KIM;CLH WONG;SR MARROU;DJ WOO;CM DETTMER;ST NGUYEN;CJ ELLISON;KR SHULL;JM TORKELSON, “Glass Transition Breadths and Composition Profiles of Weakly, Moderately, and Strongly Segregating Gradient Copolymers: Experimental Results and Calculations from Self-Consistent Mean-Field Theory”, Macromolecules, (2009)