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Contact: Pamela Bogdanski

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Chemical Engineering

(734) 764-7368

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Ronald G. Larson | Faculty

Ronald Larson

George Granger Brown Professor, Chemical Engineering; A.H. White Distinguished University Professor, Chemical Engineering;

Professor: Biomedical Engineering, Mechanical Engineering, Macromolecular Science and Engineering

NCRC B10-A150
rlarson@umich.edu
(734) 936-0772

 

 

Profile Story

When Ron Larson was a student at the University of Minnesota, one of his physics professors had a cartoon illustration of a roughed-up boxer taped to his office door. The caption read: “Problems worthy of attack prove their worth by hitting back.”

“I often tell students, ‘If you’re struggling it could well be because you’ve got problem really worth struggling against,’” said Larson, the George Granger Brown and A.H. White Distinguished University Professor of Chemical Engineering. “If it’s a worthy problem, don’t expect it to be an easy problem.”

But for Larson, who studies the not-quite-liquid, not-quite-solid class of substances known as complex fluids, there’s nothing quite like the moment when one of those pugilant problems begins to reveal hints to its solution.

At Bell Laboratories, where Larson worked before coming to Michigan in 1996, one such problem involved the struggle to explain why polymers, which flow relatively slowly, developed the kinds of patterns usually associated with fast-flowing streams like water or smoke.

Larson and his colleagues developed a set of equations, and every day for six or seven months, Larson would devote some time to trying to solve them. When the first set of equations didn’t pan out, he set them aside and started on a more complicated set, but nothing worked. Every day when he got home, his wife would ask if he’d found a solution, and after months of answering, “No,” he was getting discouraged. One day, she told him she’d pray that he would find the answer.

“I had no idea you could pray for such things,” Larson said.

That night he had a vivid dream in which he returned to the first set of equations. There was one value in the equation that had been a guess, and Larson had filled the space with a 1. In the dream he changed the 1 to a 10, and the answer was right there.

The next day he went to the lab and did the same thing, solving equations that went a long way toward explaining how polymers flow.

“The most rewarding part is understanding - getting insights and discovery,” he said. “That’s the thing that’s the most fun.”

His current research, supported by a National Science Foundation grant, involves a problem that the polymer physics community has been working on for 30 years. Polymers are made up of long, tangled strands, similar to a knot of fishing line. The tangles give the polymer its  elasticity, and the constant, subtle motion of the strands causes them to gradually untangle themselves. He and his students are trying to better understand what controls the rate of disentanglement, but what they’ve found so far hints that a lot of existing theories about polymer disentanglement may be wrong. Or, as he sometimes tells students when their problems get more complex rather than less, this problem is getting worthier all the time.

Larson, who also has appointments in biomedical engineering, mechanical engineering and macromolecular science and engineering, works to better understand, predict and change the behavior of complex fluids in order to develop better medicines, paints and consumer products.

Complex fluids turn up in our foods, paints, shampoos and medicines. They include polymers, molten metals, suspensions and solutions, even DNA - all of which have structure, like solids, but also the liquid-like ability to flow under the right circumstances.

Larson’s lab has helped Dow Chemical better understand how to convert paints from oil-based to latex and produce polymer coatings that control the speed at which drugs release into the body.  

Using multi-scale computer models, he and his students can manipulate virtual atoms and look at structures in nanoscale. That’s led to software that helps companies test formulations in the virtual world before anyone touches a flask in the lab.

Larson began working with polymers as a chemical engineer at Bell Labs in 1980. His work there included a collaboration with Nobel Prize winner Steve Chu that helped establish the now-common practice of using DNA to model polymer dynamics.

Chu discovered that DNA, which is bigger and easier to work with than polymer molecules, makes a great stand-in for polymers, thanks to its coiled, stretchy structure.

Larson helped him confirm this and was one of the first engineers to start using DNA to better understand how polymers behave. Their method has become a bridge between polymer chemists and biophysicists.

“It’s become the standard method of trying to understand polymer dynamics, and now that people know how to do it, they’re also also going back into biology and using these kinds of imaging methods for other biopolymers," he said. "It was an early step toward merging the polymer community and the biophysical community.”

Short Bio

EDUCATION

University of Minnesota
PhD Chemical Engineering '80
MS Chemical Engineering '77
BS Chemical Engineering '75

FAMILY

Married to Bebe with children Rachel, Emily, Andrew and Eric.

Research & Teaching

RESEARCH INTERESTS

Rheology and Flow of Complex Fluids. Many everyday substances are not readily classified as solids or liquids, but have flow properties (i.e., rheology) somewhere in between. Such fluids typically have a polymeric or colloidal microstructure much larger than the atomic which dominates the rheological (i.e., flow) properties. Through rheological experiments, theory, and computer simulations, the Larson group is working out the relationship between the structure of these complex fluids and their rheology. Such knowledge is valuable in the optimal design of such fluids for applications in the polymer, pharmaceutical, and consumer products industries. Of particular interest at present are branched polymer melts, surfactant solutions, coating fluids, colloids and biopolymers. The group has current projects on the rheology of surfactant solutions, including those used in shampoos and body washes, and on the interfacial action of dispersants used in oil-spill clean up.  We also have a project to determine how best to control the rheology of latex coatings. We are developing advanced theories for the rheological properties of entangled polymers with long-chain branching. We also helping design novel methods of high-speed manufacture of nanofibers, using rotary jet spinning. The work includes experimental, theoretical and computational components.

Molecular Simulations of Complex Fluids and Materials. Our group has multiple projects involving molecular simulations of polymers, surfactants, and colloids. These include molecular dynamics simulations at the atomistic level, starting from interactions between atoms derived in part from ab initio (quantum mechanical) calculations, coarse-grained molecular dynamics simulations, Brownian dynamics simulations, Stochastic Rotation Dynamics and Stokesian dynamics simulations.  We are specifically looking at polymers in strong flows, at levels of resolution ranging from atomistic simulations of short chains to Brownian dynamics simulations of very long chains. This includes simple flows as well as flows of polymers through complex geometries, such as channels with contractions. We are also simulating self-assembling colloids, where anisotropic interactions between particles allow unique structures to self assemble and re-configure. We are carrying out atomistic and coarse-grained simulations of latex particle dispersions to better control their flow properties. We are simulating the interactions between drugs and cellulosic polymers used to optimize their release in the body.

Polyelectrolyte Interactions. We are studying the complexes formed by polymers of opposite charge, which are used to make layer-by-layer assemblies used for drug delivery or structured materials. A special case is that of negatively charged DNA interacting with either positively charged proteins or positively charged nanoparticles. In particular, we are examining the process by which such proteins find their target sites along double-stranded DNA molecules, using both single-molecule imaging methods and theory.

Graduate Students:

  • Indranil Saha Dalal
  • Priyanka Desai
  • Wenjun Huang
  • Kyle Huston
  • Lei Jiang
  • Ali Salehi
  • Xueming Tang
  • Shi Yu
  • Fang Yuan
  • Weizhong Zou

Post docs:

  • Daniel Beltran
  • Prateek Jha
  • Jun Liu
  • Mohammad Taghavi
  • Shihu Wang

Visiting Scholars:

  • Tongyang Zhao
  • Miqiu Kong

COURSES TAUGHT

Undegraduate

  • ChE 341 - Undergrad. Fluid Mechanics (shared)
  • ChE 342 - Mass and Heat Transfer
  • ChE 466 - Process Dynamics and Control

Graduate

  • ChE 527 - Fluid Flow
  • ChE 629 - Complex Fluids
  • ChE 696/EECS 598 Biological Application of Micro- and Nanofluidics

Extension Courses (Chulalongkorn University, Bangkok, Thailand)

  • Polymer Rheology (shared)
  • Polymer Physics (shared)

    Professional Experience

    University of Michigan
    Chemical Engineering Department 
    Ann Arbor, Michigan

    • George Granger Brown Professor, 2000-
    • Chair, 2000-2008
    • Professor, 1996-

    University of Michigan
    Macromolecular Science and Engineering
    Mechanical Engineering
    Ann Arbor, Michigan

    • Professor

    Bell Laboratories

    • Member of Technical Staff, 1980-1996

    PROFESSIONAL SERVICE

    • AIChE Professional Progress Award Committee, 1999-2000
      American Institute of Chemical Engineering
    • Ford Prize Committee, 1997-1998
      American Physical Society
    • Fluid Mechanics Steering Committee, 1990-1995, 2001-present
      American Institute of Chemical Engineering
    • Editorial Board – Rheol. Acta, 1994–present
    • Executive Committee, 1991-2001
      Society of Rheology
    • President, Society of Rheology, 1997-1999
      Society of Rheology

    Honors & Publications

    HONORS & AWARDS

    • Distinguished University Professorship, 2014
      University of Michigan
    • Stephen S. Attwood Award, College of Engineering, 2013
      University of Michigan
    • Member, 2003
      National Academy of Engineering
    • Bingham Medal, 2002
      Society of Rheology
    • Alpha Chi Sigma Award, 2000
      American Institute of Chemical Engineers
    • Publication Award, Journal of Rheology, 1999
    • Excellence Award, 1998
      Department of Chemical Engineering, University of Michigan
    • Prudential Distinguished Visiting Fellow, 1996
      Cambridge University, England
    • Fellow, 1994
      American Physical Society
    • Distinguished Member of Technical Staff, 1988
      Bell Labs


    BOOKS

    • Structure and Rheology of Molten Polymers: From Structure to Flow Behavior and Back Again, Hanser Gardner (2006)
    • Constitutive Equations for Polymer Melts and Solutions , Out of Print, photocopied versions can be ordered by email for a $20 fee for photocopy expenses from Ron Larson at rlarson@engin.umich.edu
    • The Structure and Rheology of Complex Fluids , Oxford University Press (1999)

    RECENT JOURNAL PUBLICATIONS

    • N. Watari and R.G. Larson, Phys. Rev. Lett. 102:246001 2009; “Shear-Induced Chiral Migration of Particles with Anisotropic Rigidity.
    • L.T. Shereda, R.G. Larson, and M.J. Solomon, Phys. Rev. Lett. 101:038301; "Local Stress Control of Spatiotemporal Ordering of Colloidal Crystals in Complex Flows."
    • Watari, M. Doi, and R.G. Larson, Phys. Rev. E, 78:011801 2008 "Fluidic trapping of deformable polymers in micro-flows."
    • Z.W. Wang and R.G. Larson Macromolecules 41:4945-4960 2008 "Constraint Release in Entangled Binary Blends of Linear Polymers: A Molecular Dynamics Study."
    • M.S. Rahman, R. Aggarwal, R.G. Larson, J.M. Dealy, and J. Mays, Macromolecules, 41:8225-8230 2008, "Synthesis and Dilute Solution Properties of Well-Defined H-Shaped Polybutadienes."
    • X. Chen, and R.G. Larson, Macromolecules 41:6871-6872 2008 "Effect of Branch Point Position on the Linear Rheology of Asymmetric Star Polymers."
    • Y. Heo, and R.G. Larson, Macromolecules, 41:8903-8915 2008, "Universal Scaling of Linear and Nonlinear Rheological Properties of Semi-Dilute and Concentrated Polymer Solutions."
S.L. Duncan, and R.G. Larson Biophys. J., 94:2965-2986, 2008 "Comparing Experimental and Simulated Pressure-Area Isotherms for DPPC."
    • L. Monticelli, S.K. Kandasamy, X. Periole, R.G. Larson, D.P. Tieleman, and S.J. Marrink, J. Chem. Theory and Computation, 4:819-834 2008 "The MARTINI Coarse-Grained Force Field: Extension to Proteins."
    • H. Lee and R.G. Larson, J. Phys. Chem. B 112:7778-7784 2008, "Coarse-Grained Molecular Dynamics Studies of the Concentration and Size Dependence of Fifth- and Seventh-Generation PAMAM Dendrimers on Pore Formation in DMPC Bilayer."
    • H. Lee and R.G. Larson, J. Phys. Chem. B 112:12279-12285 2008, "Lipid Bilayer Curvature and Pore Formation Induced by Charged Linear Polymers and Dendrimers: The Effect of Molecular Shape."
    • S.P. Holleran and R.G. Larson, Macromolecules 41:5042-5054 2008 "Multiple Regimes of Collision of an Electrophoretically Translating Polymer Chain Against a Thin Post."
    • S. Jain and R.G. Larson, Macromolecules 41:3692-3700 2008 "Effects of Bending and Torsional Potentials on High-Frequency Viscoelasticity of Dilute Polymer Solutions."