Jeffrey S. Moore

Research

Our research involves the synthesis and study of large organic molecules and the discovery of new polymeric materials. Most projects relate to one of three areas: new macromolecular architectures and their supramolecular organization; responsive polymers including self-healing materials; mechanochemical transduction. In general, our group uses the tools of synthetic and physical organic chemistry to address problems at the interface of chemistry and materials science.

Designing New Macromolecular Architectures

Well-defined, carbon-rich molecular architectures of nanoscale dimension are a class of matter finding use as sensory materials for explosives detection, active layers for nanofiltration membranes, and precursors to novel carbon-based anodes in batteries. Scalable synthetic methods are needed before widespread commercialization of these materials can be realized. The Moore group is known for its success in developing, adapting, and utilizing modern synthetic methods to construct complex, yet well-defined, carbon-rich materials. Concurrent with advances in cyclooligomerization based on alkyne metathesis, we have demonstrated the ability to produce multi-gram quantities of multiple macrocycles. However, the ability to predict the products in these reactions is currently not possible because the design rules for dynamic macrocylization have yet to be established. This gap in knowledge points to the need for a systematic investigation of the parameters that govern linear polymerization vs. cyclooligomerization in alkyne metathesis reactions under thermodynamically controlled conditions. These systematic studies will help establish how to rationally construct monomers to achieve the desired targets. The exploration of new strategies and methods will potentially enable the preparation of structures with unprecedented complexity. The overarching objective of this project is the development of scalable methods for the synthesis of structurally well-defined, carbon-rich architectures of nanoscale dimension. The alkyne metathesis reaction is the method-of-choice for oligomerization and cyclooligomerization of carbon-rich precursors because it employs dynamic covalent chemistry that preserves the high-carbon content of the carbon-carbon triple bond. In a single synthetic transformation, it is possible to prepare large and structurally complex products from relatively simple small-molecule precursors. We also plan to conduct exploratory work on the preparation of moreadvanced carbon-rich targets through the use of macrocyclic building blocks.

Representative Publications

1. Elliott, E.L.; Hartley, S.; Moore, J.S. "Covalent Ladder Formation Becomes Kinetically Trapped Beyond Four Rungs" Chem. Comm. 2011, 47, 5028-5030 DOI: 10.1039/C1CC11242B
2. Hartley, C. S.; Elliott, E. L.; Moore, J. S. "Covalent Assembly of Molecular Ladders," J. Am. Chem. Soc. 2007, 129, 4512-4513. DOI: 10.1021/ja0690013
3. Naddo, T.; Che, Y.; Zhang, W.; Balakrishnan, K.; Yang, X.; Yen, M.; Zhao, J.; Moore, J. S. "Detection of Explosives with a Fluorescent Nanofibril Film,"J. Am. Chem. Soc. 2007, 129, 6978-6979. DOI: 10.1021/ja070747q
4. Zhang, W.; Moore, J. S. "Shape-Persistent Macrocycles: Structures and Synthetic Approaches from Arylene and Ethynylene Building Blocks," Angew. Chem. Int. Ed. 2006, 45(27), 4416-4439. DOI: 10.1002/anie.200503988

Self-Healing Polymers

Self-healing microvascular material systems have attracted attention for their ability to achieve multiple healing cycles in response to mechanical damage. Current microvascular fabrication methods are limited in their ability to integrate microvascular networks into commercial composite materials. In order to extend self-healing materials to commercial applications, we have developed an approach that is compatible with large-scale composite manufacturing. Sacrificial fibers are woven into 3D fiber composites and embedded in a matrix (e.g. epoxy). The sacrificial fiber depolymerizes when heated, resulting in a vaporization of fiber material, while the application of a vacuum allows controlled removal of gaseous monomer from the matrix. The hollow channels produced are high-fidelity inverse replicas of the original fiber's diameter and trajectory. This method, referred to as "VaSC" (Vaporization of Sacrificial Components), has been used to create microvascular fiber-reinforced composites with channel lengths up one meter whose channels can subsequently be filled with a variety of liquids including aqueous solutions, organic solvents and liquid metals. By circulating fluids with unique physical properties, we demonstrate the ability to create a new generation of biphasic pluripotent composite materials where the solid phase provides strength and form and the liquid phase provides interchangeable functionality.

In our work, we explore the possibility of constructing high-aspect ratio microchannels by embedding commercial poly(lactic acid) (PLA) fibers in an epoxy matrix and then triggering thermal depolymerization. PLA depolymerization temperature is lowered by the addition of a variety of depolymerization catalysts so as to accommodate conventional matrix manufacturing protocol. We also explore another fiber manufacturing method which utilizes traditional dry fiber spinning technique. The sacrificial fibers produced via fiber spinning show promising advantages over the commercial PLA fibers in term of depolymerization rate and microchannel integrity. This fiber spinning method is likely to be the best method for microvascular composite fabrication.

Composites fabricated using this method are currently limited, in practice, to a single vascular network. Future work will seek a general solution to this limitation by adding a coating on sacrificial components (fibers) which can be used to deliberately manipulate the spacing and transport properties between the microchannels. The variable properties of the coating will add new functionalities by allowing transport properties between channels to be controlled. Coated sacrificial fibers (CSFs) are thus envisioned as a building block for fabricating the next-generation of advanced composites.These CSF building blocks might enable manufacturable routes to synthetic composites that emulate countercurrent circulatory and respiratory functions.

Our self-healing research is done in collaboration with the Autonomous Materials Systems division of the Beckman Institute at the University of Illinois.

Representative Publications

1. Wilson, G. O.; Henderson, J. W.; Caruso, M. M.; Blaiszik, B. J.; McIntire, P. J.; Sottos, N. R.; White, S. R.; Moore, J. S. "Evaluation of peroxide initiators for radical polymerization-based self-healing applications," J. Polym. Sci., Part A: Polym. Chem. 2010, 48, 2698-2708. DOI: 10.1002/pola.24053
2. Caruso, M. M.; Blaiszik, B. J.; White, S. R.; Sottos, N. R.; Moore, J.S. "Full Recovery of Fracture Toughness using a Non-Toxic Solvent-Based Self-Healing System," Adv. Funct. Mater. 2008, 18, 1898-1904. DOI: 10.1002/adfm.200800300
3. Toohey, K. S.; Sottos, N. R.; Lewis, J. A.; Moore, J. S.; White, S. R. "Self-Healing Materials with Microvascular Networks," Nature Materials, 2007, 6, 581-585. DOI: 10.1038/nmat1934
4. White, S. R.; Sottos, N. R.; Geubelle, P. H.; Moore, J. S.; Kessler, M. R.; Sriram, S. R.; Brown, E. N.; Viswanathan, S. "Autonomic Healing of Polymer Composites," Nature, 2001, 409 , 794-797. DOI: 10.1038/35057232

Mechanochemistry

At the intersection of mechanics and chemistry, mechanochemistry is a subject that embraces many everyday phenomena including wear and abrasion, friction and lubrication, and stress-accelerated degradation of materials. Our concept of a mechanophore is a stress or strain activated molecular unit that can be inserted into a polymeric material to provide a molecular-scale reading of the local mechanical state or to transform materials properties in response to the local mechanical environment. First-generation mechanophores developed by the Moore group are designed to take advantage of simple, strategically placed chemical equilibria and one-step mechanisms with low kinetic barriers. Building further on these important concepts, work on second-generation mechanophores currently underway encompasses a variety of new goals and challenges. A few key mechanochemical research themes within the group include: Damage Sensing, Catalysis, Macromolecular Recognition and Response, Polymer Architecture Effects and Masked Chemical Reactivity in a Mechanophore.

• Damage Sensing: The ability to detect damage is a skill we use almost everyday, but rarely do we give much thought to it. Whether it’s noticing a new scratch on our car or checking the tires for wear and tear, these quick “assessments” allow us to make helpful mechanical predictions. Similarly, the development of polymeric damage sensing probes has expanded the frontiers of safety in material chemistry. The intersections between chemical sciences and applied research have produced immediate uses for these chemical probes. Using this technology, a material’s mechanical failure threshold can now be detected before a catastrophic failure occurs. In particular, interfacial debonding in composite materials can significantly affect structural properties and presents a difficult challenge to detect. Our damage-sensing mechanophores are uniquely positioned to be applied in this large area of research.
• Catalysis: One goal of our research is to utilize supramolecular conformational changes brought about by mechanical force to activate catalysis. Traditionally, homogeneous catalysis is turned on by activating pre-catalysts, however, a mechanophore-based catalyst would be suitable for activation through the application of external stresses. The catalyst would remain in the ground state (not active) until the mechanical stimulus exceeds the activation threshold, generating an active catalyst. This concept opens the door to a new class of load bearing materials based on force-coupled catalysis.
• Macromolecular Recognition and Response: A significant benefit to first-generation (color changing) mechanophores is their high sensitivity to stress/strain energies combined with their ability to function in polymers at low concentration while still providing optical recognition in a bulk sample. This mechanophore design strategy is targeted to provide localized recognition and response. To elicit a bulk response across a polymer such that fundamental property changes are brought about we are now developing the next generation of mechano-responsive materials. Our intent is to develop monomeric mechanophores that can be incorporated into polymers with high fidelity or can be polymerized directly. Materials modified with high concentrations of mechanophores will provide a reactive infrastructure leading to macromolecular reaction events such as cross-linking under stress or self-healing after a damage event.
• Polymeric Architecture Effects: Another goal of our research is to answer the fundamental question: how does polymer architecture influence mechanochemical transduction of energy to a mechanophore? We aim to gain insight to this question through the synthesis and mechanical testing of a variety of mechanophore-linked polymer frameworks. The implications of this work could lead to the targeted design of polymeric materials that control the stress and strain activation pathways of mechanophores and enhance the rate of mechanophore activation.
• Masked Chemical Reactivity: Often the “rules” of polymer synthesis preclude the incorporation of reactive functional groups in the polymer matrix. These reactive functionalities can be masked within a mechanophore and unveiled upon the application of external stress or strain. Upon unveiling, these reactive groups can do further work, either catalyzing chemical reactions or inducing polymer self-healing.

Ultimately we believe our group is well positioned to realize the next major advancement in the field of mechanochemistry as well as further our understanding of matter as it experiences mechanical energy input.

Our mechanochemistry research is done in collaboration with the Autonomous Materials Systems division of the Beckman Institute at the University of Illinois.

Representative Publications

1. Kingsbury, C.M.; May, P.A.; Douglas, D.A.; White, S.R.; Moore, J.S. and Sottos, N.R. "Shear Activation of Mechanophore-Crosslinked Polymers" J. Mater. Chem., 2011, 21, 8381-8388. DOI: 10.1039/C0JM04015K
2. Beiermann, B.A.; Davis, D.A.; Kramer, S.L.B.; Moore, J.S.; Sottos, N.R.; White, S.R. "Environmental Effects on Mechanochemical Activation of Spiropyran in Linear PMMA." J. Mater. Chem., 2011, 21, 8443-8447. DOI: 10.1039/C0JM03967E
3. Lee, C. K.; Davis, D. A.; White, S. R.; Moore, J. S.; Sottos, N. R. Braun, P. V.J. Am. Chem. Soc. 2010, 132, 16107-16111. DOI: 10.1021/ja106332g
4. Kryger, M. J.; Ong, M. T.; Odom, S. A.; Sottos, N. R.; White, S. R.; Martinez, T. J.; Moore, J. S. J. Am. Chem. Soc. 2010, 132, 4558-4559. DOI: 10.1021/ja1008932
5. Caruso, M. M.; Davis, D. A.; Shen, Q.; Odom, S. A.; Sottos, N. R.; White, S. R.; Moore, J. S. Chem Rev. 2009, 109, 5755-5798. DOI: 10.1021/cr9001353

Energy Storage Materials

Several members of the Moore group are working on projects related to extending the lifetimes and efficiencies of electronic materials. We are specifically interested in extending lifetimes of materials that are subjected to mechanical stress. Mechanisms causing mechanical failure in electronic materials range from the mismatch of thermal expansion coefficients of a metallic circuit and its underlying polymer substrate to the loss of contact in particles within battery electrodes due to fragmentation upon repeated lithiation/delithiation cycles in lithium ion batteries. Additionally, we are interested in developing anodes for lithium ion batteries that are comprised of graphitic materials with advanced architectures that allow for more efficient lithiation – and therefore higher capacities – for improved battery performance as compared to current battery anodes.

Self-Healing Electronics

Self-healing materials systems have largely focused on restoring functions such as mechanical properties of structural composites and barrier properties of protective coatings. We have extended this concept to the repair of damage to electronic materials, which are subjected to a variety of failure mechanisms that are related to mechanical fatigue. The self-healing concept is based on release of liquid content from microcapsule to allow for restoration of damage using the released liquid. We are interested in developing self-healing circuits and battery electrodes, both of which fail under mechanical stress.

In order to overcome the cycle life and the safety issues that plague lithium-ion battery technology, new approaches are needed that can stabilize the electrode-electrolyte interface and restore electrodes degraded by microcracks formed from repeated charge-discharge cycling. Toward this goal, we are developing new types of microcapsules in which precursor materials such as carbon nanotubes (CNTs) are suspended in organic solvents within polymer-based microcapsules. We are currently developing shells that erode under conditions of high electrical potential, temperature spikes, mechanical damage or other appropriate stimuli could release these suspensions and deliver conductive components where they are needed, thus restoring current in damaged electrical conductors. The migration of CNTs in an organic solvent in driven by an external electrical field has been previously reported. We have used this mechanism to heal gaps in mechanically damaged metallic circuits and are interested in the encapsulation of conductive materials for healing damaged electrical circuits.

Given recently obtained promising results, we intend to pursue this system further during the coming years. We will test the ability to encapsulate other components including nanoparticles, conductive polymers, and carbon-rich molecular fragments that may undergo electric field triggered assembly. Finally we plan to develop capsules that trigger the release of their contents to various stimuli, which is a major requirement for controlled release in a battery environment. In addition to mechanical damage, triggered release by thermal and electrical conditions would be beneficial to self-healing batteries. We plan to design microcapsules with smart shell walls that can erode electrochemically and this exhibit electrical potential-triggered release of contents.

Advanced Carbon Materials for Lithium Ion Battery Electrodes

Carbon is the most widely used anode materials for lithium-ion batteries. Recent advances have focused on other energy storage materials (e.g., Si, Sn, etc.) that are superior to carbon in terms of capacity. But the real-world application of these materials is inevitably limited by their poor mechanical stability during charge/discharge cycles. One of our major goals is to synthesize porous carbon materials that may act as an electrically conductive scaffold to host the above-mentioned active components. We use carbon-rich polymers as the precursor such that the high processibility of these polymers will allow for a high degree of control over the structure of the resulting carbon. We focus on constructing three-dimensional carbon architectures possessing hierarchical pores and channels. Higher dimensionality would improve the gravimetric and volumetric usability of active electrode materials, and the porous structure would help minimizing the resistance for lithium ions to diffuse across the entire electrode. Built on this work we will explore embedding more advanced energy storage materials into the porous carbon to construct electrode materials with both improved energy density and power density.

Polymer-Protected Redox Shuttles

In a lithium-ion battery pack composed of series-connected cells, overcharge of an individual cell may lead to undesired chemical and electrochemical reactions among battery components, causing thermal runaway and even possible explosion of the entire battery pack. Redox shuttles are electrolyte additives that can be reversibly oxidized/reduced at particular potentials to carry the excess current between the two electrodes thus provide intrinsic overcharge protection for the battery. We are currently investigating the concept of burying a small molecule redox shuttle in a polymer chain to protect the shuttle from bimolecular reaction. The idea is analogous to proteins carrying around redox active sites, like iron-sulfur complexes. Currently, we are trying to understand the nature of polymer chain that creates microenvironment around small molecule to affect the redox behavior.

Representative Publications

1. Xue, Z.; Finke, A. D.; Moore, J. S. "Synthesis of Hyperbranched Poly(m-phenylene)s via Suzuki Polycondensation of a Branched AB2 Monomer," Macromolecules, 2010, 43, 9277-9282. DOI: 10.1021/ma102023a
2. Esser-Kahn, A. P.; Sottos, N. R.; White, S. R.; Moore, J. S. "Programmable Microcapsules from Self-Immolative Polymers," J. Am. Chem. Soc., 2010, 132, 10266-10268. DOI: 10.1021/ja104812p
3. Odom, S. A.; Caruso, M. M.; Finke, A. D.; Prokup, A. M.; Ritchey, J. A.; Leonard, J. H.; White, S. R.; Sottos, N. R.; Moore, J. S. "Restoration of Conductivity with TTF-TCNQ Charge-Transfer Salts," Adv. Funct. Mater. 2010, 20, 1721-1727. DOI: 10.1002/adfm.201000159
4. Caruso, M. M.; Schelkopf, S. R.; Jackson, A. C.; Landry, A. M. Braun, P. V.; Moore, J. S. "Microcapsules containing suspensions of carbon nanotubes," J. Mater. Chem. 2009, 19, 6093-6096. DOI: 10.1039/b910673a

Publications

Esser-Kahn, A. P.; Thakre, P. R.; Dong, H.; Patrick, J. F.; Vlasko-Vlasov, V. K.; Sottos, N. R.; Moore, J. S. and White, S. R. "Three-Dimensional Microvascular Fiber-Reinforced Composites." Advanced Materials, 2011. DOI:10.1002/adma.201100933

Esser-Kahn, A.P.; Odom, S.A.; Sottos, N.R;White, S.R; Moore, J.S. "Triggered Release from Polymer Capsules" Macromolecules 2011. Article ASAP. DOI:10.1021/ma201014n

Gross, D.E.; Moore, J.S. "Arylene-Ethynylene Macrocycles via Depolymerization-Macrocyclization" Macromolecules, 2011. Article ASAP. DOI: 10.1021/ma2006552

Elliott, E.L.; Hartley, S.; Moore, J.S. "Covalent Ladder Formation Becomes Kinetically Trapped Beyond Four Rungs" Chem. Comm. 2011. 47 (17), 5028-5030 DOI: 10.1039/C1CC11242B

Evans, M.J.; Moore, J.S. "A Collaborative, Wiki-Based Organic Chemistry Project Incorporating Free Chemistry Software on the Web" J. Chem. Ed. 2011 88 (6), 764-768 DOI: 10.1021/ed100517g

Xue, Z.; Finke, A.D.; Moore, J.S. "Synthesis of Hyperbranched Poly(m-phenylene)s via Suzuki Polycondensation of a Branched AB2 Monomer". Macromolecules. 2010, 43 (22), 9277-9282.DOI: 10.1021/ma102023a

Lee, C.K.; Davis, D.A.; White, S.R.; Moore, J.S.; Sottos, N.R.; Braun, P.V., "Force-Induced Redistribution of a Chemical Equilibrium," J. Am. Chem. Soc. 2010, 132, 16107-16111. DOI: 10.1021/ja106332g

Finke, A. D.; Moore, J. S. "Lewis acid activation of molybdenum nitrides for alkyne metathesis," Chem. Commun. 2010, 46, 7939-7941. DOI:10.1039/c0cc03113e

Esser-Kahn, A. P.; Sottos, N. R.; White, S. R.; Moore, J. S. "Programmable Microcapsules from Self-Immolative Polymers," J. Am. Chem. Soc. 2010, 132, 10266-10268. DOI:10.1021/ja104812p

Odom, S. A.; Caruso, M. M.; Finke, A. D.; Prokup, A. M.; Ritchey, J. A.; Leonard, J. H.; White, S. R.; Sottos, N. R.; Moore, J. S. "Restoration of Conductivity with TTF-TCNQ Charge-Transfer Salts," Adv. Funct. Mater. 2010, 20, 1721-1727.DOI: 10.1002/adfm.201000159

Caruso, M. M.; Blaiszik, B. J.; Jin, H.; Schelkopf, S. R.; Stradley, D. S.; Sottos, N. R.; White, S. R.; Moore, J. S. "Robust, Double-Walled Microcapsules for Self-Healing Polymeric Materials," ACS Appl. Mater. Interfaces. 2010, 2, 1195-1199.DOI: 10.1021/am100084k

Kryger, M. J.; Ong, M. T.; Odom, S. A.; Sottos, N. R.; White, S. R.; Martinez, T. J.; Moore, J. S. "Masked Cyanoacrylates Unveiled by Mechanical Force," J. Am. Chem. Soc. 2010, 132, 4558-4559.DOI: 10.1021/ja1008932

Davis, D. A.; Hamilton, A.; Yang, J.; Cremar, L. D.; Van Gough, D.; Potisek, S. L.; Ong, M. T.; Braun, P. V.; Martínez, T. J.; White, S. R.; Moore, J. S.; Sottos, N. R. "Force-induced activation of covalent bonds in mechanoresponsive polymeric materials," Nature, 2009, 459, 68-72.DOI: 10.1038/nature07970

Hickenboth, C. R.; Moore, J. S.; White, S. R.; Sottos, N. R.; Baudry, J.; Wilson, S. R. "Biasing Reaction Pathways with Mechanical Force," Nature, 2007, 446, 423-427.DOI: 10.1038/nature05681

Awards

• Fellow, American Chemical Society
• Fellow, Polymeric Materials Science and Engineering (PMSE)
• Fellow, American Academy of Arts and Sciences
• UIUC Campus Award for Excellence in Undergraduate Teaching
• LAS Dean's Award for Excellence in Undergraduate Teaching
• Alpha Epilon Delta Pre-Health Honors Society Professor of the Year Award
• Fellow, American Association for the Advancement of Science
• Alfred P. Sloan Fellow
• ACS Arthur C. Cope Scholar Award
• Dreyfus Teacher-Scholar
• NSF Young Investigator Award

Highlights

1. ACS Highlights Hyperbranched Polymers publication as "Noteworthy Chemistry" See the article here.
2. Mechanophores Featured in Popular Mechanics'"10 Tech Concepts You Need to Know for 2011" Read the article here.
3. Smashing Self-Healing! Recent Advanced Functional Materials on self-healing electronics was highlighted in Materials View. Read more here.
4. You Break It, You Fix It: Mechanochemically-activated cyanocrylates paper was highlighted in SYNFACTS. Read more here.
5. "Online Chemistry Course Offers Freedom and Flexiblity"
   See the Postmarks article by James Kloeppel.
6. Moore's research into self-healing circuits has been highlighted in Technology Review. Read the Technology Review article here.

7. Moore and collaborators design a 'first aid kit' for electrical systems. Read the RSC highlight of their work here.
8. "Mechanochemistry: Seeing Stress"
   C&E News highlights Dr. Moore's work in mechanical stress and self-sensing in polymers. Read the C&E News article here.
9. "See the force: Mechanical stress leads to self-sensing in solid polymers"
   See the News Bureau of the University of Illinois article by James Kloeppel.
10. Imitating Nature by Self-Healing Materials by Shelley Singh
    See the Economic Times article here
11. Self-Reparing Materials: A healing balm
    http://www.economist.com/displaystory.cfm?story_id=10637606
12. This Year In Nature - Our March 2007 paper was selected by Nature's editors as one of their "favourites' from papers published in 2007.
13. U of I researchers named to SciAm 50 for 2007
    http://www.las.uiuc.edu/news/2008spring/08jan_sciam50.html
14. RSC's Chemistry World published its "Cutting Edge Chemistry in 2007". There you'll read, "Jeffrey Moore at Illinois showed that chemical catalysts are sometimes not needed at all, using ultrasound instead to selectively break a target bond, giving a product that had proved inaccessible using more conventional techniques."
    http://www.rsc.org/chemistryworld/News/2007/December/18120702.asp
15. Nov. 2007 — Our 2006 article, "The Chain-Length Dependence Test", published in Accounts of Chemical Research is being featured on the ACS Publications website as a "Hot Paper" as defined by Thomson Scientific (ISI) Essential Science Indicators.
16. The Right Combination: Sottos, Moore, White Make Collaborations Productive and Fun
    http://www.beckman.uiuc.edu/news/synergy/sottosmoorewhite.html
17. Catalyst-free chemistry makes self-healing materials more practical
    http://www.news.uiuc.edu/NEWS/07/1127selfheal.html
18. Now, self-healing materials can mimic human skin, healing again and again
    http://www.news.uiuc.edu/NEWS/07/0611sottos.html
19. Nature: Mechanics meets chemistry in new ways to manipulate matter
    http://mrl.uiuc.edu/highlights/2007/20070319mooresottos.html
20. http://www.nature.com/nature/journal/v446/n7134/full/7134xia.html
    Making the paper: Jeffrey Moore
    A molecule that undergoes chemical reaction in response to stress.
21. Brute Force Breaks Bonds
    http://pubs.acs.org/cen/news/85/i13/8513notw4.html