Hall Research Group
Overview and Philosophy
We typically model polymers as chains of interaction sites or beads that each represent multiple atoms. Using these simple coarse grained models allows us to focus on the underlying physics and to understand general trends that are not dependent on the specific chemical details of the system. With such an understanding, we can predict how experimentally controllable parameters could be modified to create improved materials.
For more details, please go to our Research section.
We study the structure and dynamics of tapered block copolymers, motivated by the experimental work in the group of Prof. Thomas H. Epps, III at the University of Delaware, with whom we have an ongoing collaboration. These are polymers with two pure blocks of A and B separated by a "tapered" region in which the composition changes statistically from A to B, as shown schematically below.
Using self-consistent field theory (SCFT), we found that tapering widens the gyroid region of the phase diagram for small and intermediate length tapers. Thus, these designer polymer architectures may make it easier to form such bicontinuous phases of interest for good mechanical properties and transport applications. Molecular dynamics (MD) simulations show structures consistent with the SCFT results and help us understand the individual polymer conformations and how they change over time. Below the SCFT phase diagrams are compared for typical diblocks (left, from Cochran et al. Macromolecules 2006, 39, 2449-2451) and for polymers with a linear taper of 30% of the length of the chain (right, Brown et al. ACS Macro Letters (2013) 2 (12) 1105-1109). Phases formed in MD are indicated with data points, and selected snapshots are also shown.
Solid, non-flammable polymer electrolytes are of interest to increase safety and in some cases also to lower the cost or increase the energy density of batteries. One strategy is to use block copolymers in which one block contains either ionic groups or added salt and the other is uncharged; such materials are of interest because one phase can be optimized for good ion conduction while the other phase would provide desirable mechanical properties. A major goal of our group is to understand of how charge is transported, and how charge transport may be improved, in such single-ion conducting or salt-doped microphase separating polymers. Our coarse-grained models allow us to simulate the time and length scales of interest in these systems while still capturing the basic physics of polymer connectivity and long-range Coulomb interactions.
We are currently working on MD simulations of ion conduction and on improved fluids density functional theory methods to calculate phase behavior and help guide our simulation work. A simulation snapshot below shows a salt-doped copolymer with conducting phase beads in transparent red, non-conducting beads in transparent blue, anions in yellow, and cations in green. We aim to find how precise control of the morphology via tapering or other adjustments to the polymer architecture could lead to better transport through them. Some of this work is in collaboration with Prof. Thomas H. Epps, III, The University of Delaware.
We use coarse-grained molecular dynamics simulations to understand how clusters of ions determine the properties of polymers with a small fraction of charged groups along the backbone. The snapshots below show how the molecular scale structure of these materials changes as they are deformed (top to bottom). The left snapshots show ionic aggregates (polymer is invisible) and the right shows three selected polymers (other polymers and all counterions are invisible); both the polymers and ionic aggregates are seen to line up.
In collaboration with Professors Jessica Winter and Barbara Wyslouzil at The Ohio State University, we are working to understand how to control the dispersion of nanoparticles inside block copolymer micelles. Snapshots from dissipative particle dynamics simulations of micelle formation are shown below. At left the entire micelles are shown (only water is invisible); at right the polymers are made transparent so that the nanoparticles within the micelles are seen more clearly.
Nanoparticles may be added to polymers to improve mechanical, thermal, or optical properties of the resulting nanocomposite; car tires are a classic example, as they typically contain carbon black and/or silica particles added to styrene-butadiene rubber.
The large surface area of very small particles means that they can have a large effect on the polymer even at a low weight fraction. It also means that the state of dispersion of the particles and the properties of the polymer near the interface are crucial to determining the overall material properties. Thus, many scientific investigations focus on understanding the polymer structure and dynamics near the particle interface.
Jan 29, 2023
Hall Group visits the National Museum of the US Air Force
Prof. Hall and Hall group members visited Air Force Museum for a field trip and had ice cream at Young's Dairy!
Nov 18, 2022
Prof. Hall and Mengdi attend AIChE Annual Meeting 2022 in Phoenix
Prof. Lisa Hall and graduate student Mengdi Fan attended AIChE Annual Meeting 2022. Their talks and poster are listed below.
Mengdi Fan:
Molecular Dynamics Simulations of Single-Ion Block Copolymers: Effect of Polymer Architecture
Prof. Lisa Hall:
Coarse-Grained Modeling of Ion Transport in Salt-Doped and Single-Ion Block Copolymers
Oct 27, 2022
Pranav attend OSC SUG Conference and win first place in the flash talk competition!
Undergraduate student Pranav Jois attend the Ohio Supercomputer Cluster Statewide Users Group Conference and win the first place in the competition! Congrats Pranav! His talk is titled "Coarse-grained modeling of side-chain liquid crystal polymers: effect of the architectural properties on phase behavior".
Oct 25, 2022
Hall Group carves jack-o'-lanterns 🎃 for Halloween!
Prof. Hall invited Hall group members to her house for pumpkin carving! See these amazing jack-o'-lanterns!
Oct 13, 2022
Diego Becerra won the 2nd Postdoc Poster Award at the Annual Meeting of the Society of Rheology!
Congratulations to Dr. Becerra for winning the 2nd place Postdoc Poster Award at the Annual Meeting of the Society of Rheology 2022 in Chicago! His poster is titled "Polymer Rheology Predictions from First Principles using the Slip Link Model".
September 30, 2022
Welcome new group members!
Ph.D. students Jacob Breese and Spand Mehta have joined our research group at Ohio State. We are happy to have you, Spand and Jacob. Welcome to the Hall Research Group!
September 23, 2022
Hall Group attend the Graduate Research Symposium 2022
Graduate student Mengdi Fan and Yuanhao Zhang present posters about their research at GRS.
August 24, 2022
Mengdi Fan and Prof. Lisa Hall publish paper on Macromolecules
Graduate student Mengdi Fan and Prof. Lisa Hall published a paper titled "Effect of Tethering Anions in Block Copolymer Electrolytes via Molecular Dynamics Simulations". The paper was published in Macromolecules and can be found here.
June 04, 2022
Hall Group attend the 52nd Midwest Theoretical Chemistry Conference at OSU
Congrats to Felipe for the honorable mention of the poster and Mengdi for winning the best poster award!
Prof. Lisa Hall and Hall group members attended 52nd Midwest Theoretical Chemistry Conference. Their talks and posters are listed below.
Diego: “A Coarse-Grained Model for Side-Chain Liquid Crystalline Linear Polymers”
Felipe: “Studying Interparticle Interactions of Polymer-Grafted Nanoparticles in Solution via Coarse-Grained Molecular Dynamics Simulations”
Mengdi: “Comparing Single-ion and Salt-doped Polymer Electrolytes via Coarse-grained Simulations”
Yuanhao: “Local Analysis of Ion Structure and Dynamics in Coarse-Grained Simulations of Block Copolymer Electrolytes with Homopolymer”
May 19, 2022
Prof. Hall has been promoted to Full Professor!
We are pleased to congratulate Dr. Lisa Hall for her well-deserved promotion to Full Professor! Congratulations to Prof. Hall!
April 14, 2022
Nick Liesen successfully defends his dissertation!
Prof. Lisa Hall and Isamu Kusaka's Ph.D. student, Nick Liesen, completed his dissertation and defense on April 14th, 2022. His dissertation was titled "Nanoscale Structure and Dynamics of Entangled Polymer-Grafted Nanoparticle Assemblies and Simple Linear Ethers using Molecular Simulations". Congratulations, Dr. Liesen! Nick will join Dr. Rebecca Lindsey's group at Lawrence Livermore National Laboratory as a postdoc this summer.
April 05, 2022
Sahiti Tamirisakandala placed in the top three for Undergraduate Research Forum and successfully defends her thesis
Undergraduate student Sahiti Tamirisakandala defended her thesis on April 5th, 2022. Her thesis was titled "Molecular Dynamics of Block Copolymer Electrolytes: Effects of Tethering Anions". She also won third place in the 13th Annual Undergraduate Research Forum for Engineering and Architecture! Congratulations!
Mar 14, 2022
Hall Group attend APS March Meeting 2022 in Chicago
Prof. Lisa Hall and Hall group members attended APS March Meeting 2022! Their talks and posters are listed below.
Prof. Hall: "Coarse-Grained Modeling of Ion Mobility and Conductivity in Block Copolymers"
Felipe: "Modeling Pairs of Polymer-Grafted Nanoparticles (PGNs) in Solution to Determine their Phase Behavior"
Mengdi: "Coarse-grained Simulations of Ion Transport in Single-ion and Salt-doped Polymer Electrolytes"
Jan 22, 2022
Welcome new group member!
Dr. Diego Becerra has joined our research group as a postdoc at Ohio State. We are happy to have you, Diego. Welcome to the Hall Research Group!
October 7, 2021
Anna Schuler presents research at Ohio Supercomputer Center Statewide Users Group Meeting
High school student Anna Schuler presented a poster on her research at Ohio Supercomputer Center Statewide Users Group Meeting (virtual), October 7, 2021. Her poster was titled "Effects of graft density on entanglement number and type in model polymer-grafted nanoparticle monolayers". Great work Anna!
August 4, 2021
Kevin Shen, Mengdi Fan and Prof. Lisa Hall publish paper in Macromolecules
Previous graduate student Kevin Shen, graduate student Mengdi Fan and Prof. Lisa Hall published a paper titled "Quantifying the Effects of Monomer Segment Distributions on Ion Transport in Tapered Block Polymer Electrolytes". The paper was published in Macromolecules and can be found here.
May 10, 2021
Nick Liesen and Prof. Lisa Hall publish paper in Soft Matter
Graduate student Nick Liesen and Prof. Lisa Hall published a paper titled "The Influence of Spacer Composition on Thermomechanical Properties, Crystallinity, and Morphology in Ionene Segmented Copolymers". The paper was published in Soft Matter and can be found here.
April 21, 2021
Prof. Lisa Hall wins national AIChE Owens Corning Early Career Award!
Prof. Lisa Hall has been recognized as the winner of the Materials Engineering & Sciences Division (MESD) 2021 Owens Corning Early Career Award by the American Institute of Chemical Engineers (AIChE) organization! She joins a brilliant group of previous recipients including Bryan Boudouris, Bradley Olsen, Christopher Jewell, Rodney Priestley, Jeffrey Rimer, Thomas Epps, and Christopher J. Ellison. The MESD Owens Corning Early Career Award recognizes outstanding independent contributions to the scientific, technological, educational, or service areas of materials science and engineering. The award citation reads: "For molecular theory and simulations yielding fundamental insights into the structure and dynamics of ion-containing polymers and polymer nanocomposites."
Prof. Lisa Hall will give an invited talk in the MESD Plenary session at the 2021 AIChE Annual Meeting, during which the award will be officially given. Congratulations to Prof. Lisa Hall!
March 9, 2021
Kevin Shen, Mengdi Fan and Prof. Lisa Hall publish paper in Macromolecules featured as ACS Editors’ Choice
Previous graduate student Kevin Shen, graduate student Mengdi Fan and Prof. Lisa Hall published an invited Perspective paper titled "Molecular Dynamics Simulations of Ion-Containing Polymers Using Generic Coarse-Grained Models". The paper was published in Macromolecules and has been selected as the February 13, 2021, ACS Editors' Choice article! It has also been selected as the cover for Macromolecules, Volume 54, Issue 5!
Hall Group Outreach at COSI's Passport to the Color of Science
Prof. Lisa Hall and group members Kevin Shen and Mandy Fan attended the COSI’s first annual Passport to The Color of Science program.
Dr. Hall gave some introduction of polymers and our research to motivate students to pursue engineering and science, and showed them how to make slime by mixing glue with baking soda and eye contact solution, which cross links the polymers. Kevin and Mandy demonstrated the interactive molecular dynamics setup with a haptic joystick and 3D monitor, where they can virtually interact with polymer molecules to see how they behaved on a microscopic scale.
Nearly 200 8th grade girls from a dozen schools across the district spent the day at COSI participating in their new signature diversity and inclusion program, The Passport to the Color of Science, a STEM career exploration program for middle school students. COSI’s Passport to The Color of Science is an annual program that showcases the incredible contributions to Science, Technology, Engineering and Math made by women and persons of color who are doing extraordinary work here in Columbus, Ohio. Students had the opportunity to interact with 11 scientists ranging from doctors, ecologists, chemists, biologists, and engineers, and more.
Hall Group Tour for Breakfast of Science Champions
On Wednesday Nov. 8, 2019, the Hall Group hosted groups of middle school students through the Breakfast of Science Champions (BoSC) event learning about polymer physics.
The Breakfast of Science Champions is an outreach event in which middle school students from Columbus City Schools come to OSU for a day of hands-on science activites! Mandy and Akkash showed them how to make slime by mixing glue with baking soda and eye contact solution, which cross links the polymers. Kevin demonstrated the interactive molecular dynamics setup, where they can virtually interact with polymer molecules to see how they behaved.
Outreach with the STEAM Factory at Franklinton Fridays
Group members Kevin Shen and Mandy Fan attended the STEAM factory (400 W Rich Street) as part of the Franklinton Fridays event on April 12th. With the help of a haptic joystick and 3D monitor, the general public was given insights into polymer behavior on a microscopic scale. Using Mardi Gras beads in a bowl (much to the delight of those who stopped by!) along with organic chemical samples, we were able to explain the effect of polymer chain length on viscosity. These simple demonstrations sparked some insightful questions, and we believe that we were able to pique peoples interest in polymer physics!
Hall Group Tour for Breakfast of Science Champions
On Wednesday Nov. 7, 2018, the Hall Group hosted groups of middle school students learning about polymer physics through the Breakfast of Science Champions (BoSC) event. The Breakfast of Science Champions is an outreach event in which middle school students from Columbus City Schools come to OSU for a day of hands-on science activities! Prof. Hall showed them how to make slime by mixing glue with baking soda and eye contact solution, which cross links the polymers. Kevin demonstrated the interactive molecular dynamics setup, where they can virtually interact with polymer molecules to see how they behaved.
Hall Group Tour for ASPIRE workshop attendees
Hall group students Kevin Shen, Jeffrey Ethier, and Elizabeth Jergens hosted groups of high school female students learning about physics through the ASPIRE Workshop. While introducing polymer research in the Hall Group, the students were able to make their own slime by crosslinking polymers. The group was also able to visualize and feel how polymers move with our interactive molecular dynamics simulation. This workshop is held every year and supported by the Department of Physics at Ohio State University. More information about the program can be found here.