Seminars

Multicomponent High-Entropy Cantor alloys (Cantor alloys – the true story)

Brian Cantor

Department of Materials, University of Oxford; and Brunel Centre for Advanced Solidification Technology, Brunel University

10:30 am Pacific Time, 04/17/2023

Abstract:  All human advances have depended on making new materials, and all materials are alloys, i.e. mixtures of several different starting materials or components.  So the history of the human race has been the continued invention of new materials by discovering new alloys.  Recently a new way of doing this, by manufacturing multicomponent high-entropy alloys, has shown that the total number of possible materials is enormous, even more than the number of atoms in the galaxy, so we have lots of wonderful new materials yet to find.  And multicomponent phase space contains a surprisingly large number of single-phase multicomponent solid solutions.  The first group of these which was discovered are called Cantor alloys, an enormous composition range with a single-phase fcc structure, based loosely on the original equiatomic five-component Cantor alloy CrMnFeCoNi.  This talk will discuss briefly the previous history of alloying, the discovery of multicomponent alloys, the structure of multicomponent phase space, the fundamental thermodynamics of multicomponent solid solutions such as the Cantor alloys, the complexity of local atomic and nanoscale configurations in such materials, the effect of this on properties such as atomic diffusion, dislocation slip, and the resulting outstanding mechanical properties and potential applications, including at low and high temperatures, for corrosion and radiation resistance, and to enhance recycling and re-use.

Biography: Brian Cantor is an Emeritus Professor in the Department of Materials at the University of Oxford and a Research Professor in the Brunel Centre for Advanced Solidification Technology (BCAST) at Brunel University.  He is also a trustee of the UK National Science Museum Group and a chief editor of the new Springer-Nature journal High Entropy Alloys & Materials.  He was previously Vice-Chancellor of the University of York and of Bradford University, Head of Mathematical and Physical Sciences at the University of Oxford, a research scientist and engineer at General Electric Research Labs in the USA, and worked briefly at Banaras Hindu University, Washington State, Northeastern University, IISc Bangalore and the Kobe Institute.  He founded and built up the World Technology Universities Network, the UK National Science Learning Centre, the Hull-York Medical School, and Oxford’s Begbroke Science Park.  He was a long-standing consultant for Alcan, NASA and Rolls-Royce, and chief editor of Progress in Materials Science.  He invented the new field of multicomponent high-entropy alloys and discovered the so-called Cantor alloys.  In 1998 he was made a Fellow of the Royal Academy of Engineering (FREng) as “a world authority on materials and manufacturing”; and in 2013 he was made a Commander of the British Empire (CBE) by the Queen for “services to higher education”.

Using Artificial Intelligence to Discover Novel Catalysts, and Accelerate the Change to Sustainable Feedstocks within the Chemicals Industry

Christopher Tassone
SLAC National Accelerator Laboratory
11am Pacific Time, 02/24/2023

Abstract: Ambitious societal goals to address sustainability are being made across the globe.  Recent improvements in energy systems provides a path forward to decarbonizing many sectors of our economy.  However, there still remaining substantial challenges to decarbonize manufacturing.  How we make chemicals, materials and products will need to fundamentally change such that we are using net carbon neutral, or preferably net negative, feedstocks as inputs to processes which can be driven using decarbonized energy.  This will require a complete re-optimization of the integrated value chain or reaction networks that is the chemicals industry.  Additionally, these changes need to occur on the fastest timescale ever before in history if we are to meet current federal targets of a net zero economy by 2050.  In order to accomplish this we need to translate foundational basic scientific discoveries to industry orders of magnitude faster, and with a much broader scope than we have previously been able to.   

In this talk, I will discuss two facets of this problem.  Firstly, how we can accelerate the discovery of new catalysts which function on new feedstock sources, at lower energy and carbon intensity, but which can utilize the infrastructure already present in the petrochemical and agrochemical industrial complex.  Colloidal nanoparticles embedded in mesoporous hosts, provide ideal systems to control the physico-chemical properties of a catalyst in order to realize high selectivity and activity, while also understanding reactivity patterns and chemical mechanisms across an enormous range of chemical reactions.  Developing this understanding requires the synthesis of well controlled materials where the structure of the nanoparticle needs to be controlled with near atomic precision.  I will discuss how we take advantage of high throughput synchrotron x-ray scattering experiments to develop a fully automated closed-loop platform for the synthesis of nanostructured catalysts.  We are able to demonstrate that in as few as 30 unsupervised experiments our AI is able to determine how to synthesize a class of nanocrystals of varied sizes, inform researchers about what syntheses are improbable, and provide a model which can be queried to perform virtual syntheses without running subsequent experiments.  These developments provide a roadmap as to how to build AI driven R&D to both predict catalytic targets as well as how to make them.

Secondly, the change to carbon neutral or carbon negative feedstocks will require society to move away from fossil as the primary input into chemicals manufacturing, and towards new feedstocks such as biomass, captured CO₂, or waste streams.  Post-consumer waste plastic provides an attractive feedstock because it is carbon dense, and the unmitigated waste provides secondary societal challenges.  However, the transformation of macromolecules designed for long term stability presents a unique challenge not only due to having bonding motifs which are recalcitrant towards deconstruction, but also due to formulations designed generally to be immiscible and insoluble with the components of most existing catalytic chemistries.  I will discuss how we are using advanced characterization to inform the development of new catalytic approaches for the deconstruction of waste plastic to high grade monomers.  We find that the polymer uptake of catalyst and reagent molecules in heterogeneous mixtures containing solvent, catalyst, and polymer is one of the keys to achieving high activity by moving from a surface limited to a bulk deconstruction process.      

Biography: Christopher Tassone has been interested in understanding the structure of things since he received his first microscope at the age of six.  He received his bachelors of science degree in Chemistry at Santa Clara University where he performed undergraduate research with NASA Ames laboratory to develop nanoscale water sensors for extra planetary probes.  He received his PhD in Physical Chemistry from UCLA, developing methods to control the molecular structure of plastic semiconductors.  As the materials science division director at SSRL, at SLAC National Accelerator Laboratory, he develops characterization methods for understanding the structure of materials, and how to make them. 

High-Entropy and Complex, Concentrated Alloys: New Opportunities and Challenges for Interdisciplinary Research

Daniel B. Miracle
Air Force Research Laboratory
2pm Pacific Time, 03/08/2022

Abstract:

High-entropy and complex, concentrated alloys (HEAs and CCAs) are more than a new class of materials, they represent a new approach to conceive, explore, design, and develop new materials. This new approach, using three or more constituents at concentrations that make it difficult to distinguish a single dominant component, opens new opportunities to discover materials with high societal impact in areas that have become idea-limited with conventional alloying concepts. However, new challenges must be overcome. Standard computational and experimental methods used to characterize classical, dilute materials are sometimes ineffective, so that new methods and workflows must be established. For example, CALPHAD methods often require significant extrapolation into unknown composition space, standard X-ray diffraction methods often fail to identify ordered intermetallic phases, and an expansive number of distinct local environments make it difficult to characterize chemical short-range ordering. Even more challenging, the truly vast scope of multi-dimensional composition space raises questions about the ability to generalize detailed characterizations made on a single alloy to the broader class of HEAs and CCAs. The purpose of this talk is to initiate a provocative and challenging new discussion in the field of HEAs and CCAs to critically consider the most impactful ways to harness a major new characterization capability in the US.

Self-assembly 2.0. Molecular assembly regulated through chemical reactions

Job Boekhoven
Department of Chemistry, Technical University of Munich
11am Pacific Time, 11/19/2021
Click here to view a recorded version of this seminar

Abstract:
Molecular self-assembly is the process in which molecules combine into superstructures held together through non-covalent interactions. Over the last decades, supramolecular chemists have perfected this art, and we can now create Gigadalton structures in which each atom is placed with angstrom precision. More importantly, the unique properties of the emerging assemblies have found their way in everyday life like, for example, the liquid crystals in our displays. Nevertheless, we are completely overshadowed by biology when it comes to assembly with molecular building blocks. Indeed, the biological cell has the same molecular toolbox at its disposal for creating structures; it also uses non-covalent interactions to hold molecules together. The difference can be partly explained because biological structures are governed not only by non-covalent interactions but also by reactions forming covalent ones. Arguably, molecular self-assembly offers the structures; chemical reactions govern the dynamics of these structures. In this talk, I will guide you through our journey to introduce an equivalent principle in synthetic supramolecular self-assembly. I will introduce the concept of molecular self-assembly regulated through chemical reactions, our design rules and possible applications.

Bio:

Job Boekhoven holds a Ph.D. degree from the TU Delft and spent his postdoctoral training at Northwestern University. He currently holds a Rudolf Mößbauer tenure track position at the TU Munich. Notable awards include an ERC starting grant, the Volkswagen foundation Life? grant, and most recently the VCI lecturer award.

Combating Wear and Corrosion Resistance Tradeoff of Metals via Microstructure Design

Wenjun (Rebecca) Cai
Department of Materials Science and Engineering (MSE), Virginia Tech
caiw@vt.edu
1 PM PDT, May 28, 2021
Click Here to view a recorded version of this seminar

Abstract:

The increasing complexity and severity of service conditions in areas such as aerospace and marine industries, nuclear systems, microelectronics, batteries, and biomedical devices etc., imposes great challenge on the reliable performance of metal subjected to simultaneous surface stress and corrosion. However, the design of strong and corrosion-resistant alloys, especially those containing lightweight elements such as Al are challenged by the tradeoff between strength and corrosion resistance. Solute tends to have small equilibrium solubility limit in Al due to their relatively large negative enthalpy of mixing with Al. As a result, the formed precipitates strengthen the alloys, but compromises corrosion resistance due to their microgalvanic coupling with the metal matrix. Towards this end, this talk will focus on the development of novel microstructure design strategies for metals to mitigate the combined attack of wear and corrosion (i.e. tribocorrosion) under harsh conditions. Two design strategies will be discussed to overcome this long-standing dilemma: by forming solid solution alloys and nanostructured multilayers. In the first example, alloying Al with excess manganese (Mn) in solid solution was found to simultaneously enhance the wear and corrosion resistance of Al. Specifically, higher Mn concentration was found to improve the protectiveness of the passive film, increase the hardness via solid-solution strengthening and microstructure refinement, and accelerate the repassivation kinetics during tribocorrosion of Al. Interestingly, it was also found that Mn enhanced the aqueous corrosion resistance of Al without participating in surface oxidation. Instead, the selective dissolution of Mn was believed to increase the free volume at the metal/oxide interface to facilitate the formation of a denser, thinner oxide layer with closer to stoichiometry composition. In the second example, ultrahigh tribocorrosion resistance of metals was achieved via nano-layering, where the presence of abundant interfaces and nanoscale chemical modulation were found to effectively restrict plastic deformation, reduce micro-galvanic corrosion and surface reactivity. These studies provide insights for general design guidelines to engineer more robust, high-performance metals for use under harsh conditions.

“Electro-Assembly” – Neutralizing charged biomolecules with electricity

Lior Sepunaru UCSB
1 PM PDT, April 16, 2021
Click Here to view a recorded version of this seminar

Abstract:

In this talk, I will describe a recently developed multidisciplinary approach to study and manipulate freely diffusing biological molecules in solution. Using pulsed voltammetry, individual charged amino acids are directly deprotonated on a sufficiently biased platinum electrode. The phenomenon is extended and applied to study peptides encompassing charged groups. We discovered a linear correlation between the formal reduction potential of the charged moieties and their pKa. The trend elegantly reflects how electrochemistry can be used to measure the intrinsic basicity/acidity of amino acids within a polymeric construct. These sets of experiments sparked the idea of investigating proteins as well. For this, we chose to examine the electrochemical properties of Reflectin, a histidine-rich protein that is responsible for the camouflage properties of squid skin. The histidine groups are “discharged” electrochemically in a similar way to their individual counterparts. Moreover, the electrochemical neutralization of the protein induces protein assembly and thus acting as a surrogate for naturally occurring neutralization processes such as phosphorylation. The method described is interesting because it extends the scope of electrochemistry in general. Aside from using voltage to study the thermodynamics of a system, or use voltage to derive some (bio)chemical reactions, we can now manipulate biomolecules. Moreover, coupling the heterogeneous deprotonation pathway with spectroscopy raises the possibility to control the extent of protein assembly and to observe never-seen-before intermediates generated during the assembly process.

Metabolic Soft Matter Systems:
Catalytic Protocells and Materials with Lifecycles

Andreas Walther

A3BMS Lab, Active, Adaptive and Autonomous Bioinspired Materials, Department of Chemistry, University of Mainz, 55128 Mainz, Germany.
DFG Cluster of Excellence @ FIT “Living, Adaptive and Energy-Autonomous Materials Systems” (livMatS), Freiburg Center
for Interactive Materials and Bioinspired Technologies, University of Freiburg, 79110 Freiburg, Germany.

*andreas.walther@uni-mainz.de; @WaltherLab

11 AM PST, April 2, 2021

Zoom Meeting Link Sent Internally
Please contact Prof. Zhibin Guan at zguan@uci.edu if you are interested in meeting Prof. Andreas Walther via Zoom

Abstract:

Living self-organizing systems operate far-from-equilibrium and maintain functions by constant energy dissipation in adaptive steady states, and are orchestrated through feedback loops and metabolic reaction networks to allow tailored response in complex sensory landscapes.

Some of the next steps in self-assembling systems are to approach multicomponent co-assembling systems, and to master temporal behavior as well as complex adaptation mechanisms. The latter require new types of internal control mechanisms, such as kinetic control over opposing reactions (builtup/destruction), the integration of feedback mechanisms, or the use of energy dissipation to sustain structures only as long as a chemical fuel is available. This ultimately goes along with a transition towards out-of-equilibrium complex systems, in which multiple components self-assemble dynamically in a nonlinear and adaptive fashion. Higher complexity and new functions are in reach by essentially embedding metabolic reaction networks into these systems.

In this talk I will I will discuss the formation of DNA-based protocell architectures with the ability to house abiotic catalysts driving downstream morphological adaptations, as well as two conceptual pathways towards chemically fueled out-of-equilibrium systems using activation/deactivation networks. The latter allows to program self-assemblies and materials with lifetimes and programmable steady state dynamics. This will be showcased for different self-assembling systems (polymers, peptides, DNA), and the connection to hydrogels and photonic materials demonstrates possibilities for new horizons in materials science.

Selected References:

Emerging area article: LH, AW “Approaches to Program the Time Domain of Self-Assemblies“10th year Soft Matter issue, 2015, 11, 7857. Review: AW “From Responsive to Adaptive and Interactive Materials and Materials Systems: A Roadmap” Adv. Mater. 1905111 (2020). Review: RM, AW “Materials learning from life: Concepts for active, adaptive and autonomous molecular systems”. Chem. Soc. Rev. 2017, 46, 5588;

Selected References: Nat. Nanotechnol. 1856 (2020). Nat. Commun. 11, 3658 (2020). J. Am. Chem. Soc. 2020, 142, 2, 685; Sci. Adv., 5, eaaw0590, (2019). Angew. Chem. Int. Ed. 2020 doi:10.1002/anie.202003102; Nature Nanotech. 2018, 13, 730; Nano Lett. 2017, 17, 4989; Chem. Sci. 2017; 8, 4100; Adv. Mater. 2017, 29, 1521; Angew. Chem. Int. Ed., 2015, 54, 13258; Nano Lett., 2015, 15, 2213.

Bio:

Andreas Walther is a Gutenberg Research Professor for Macromolecular Materials and Systems at the Department of Chemistry at the Johannes Gutenberg University in Mainz (Germany). His research interests concentrate on developing and understanding hierarchical self-assembly concepts inside and outside equilibrium, and on using them to create Active, Adaptive and Autonomous Bioinspired Material Systems – A3BMS.

Andreas Walther is the recipient of an ERC Starting Grant and of an ERC Consolidator Grant. He is part of the European Training Networks CREANET and VITRIMAT, and he is a founding PI of the DFG Cluster of Excellence on “Living, Adaptive and Energy-Autonomous Materials Systems” (livMatS). He was a senior fellow of both the Freiburg (FRIAS) as well as the Strasbourg (USIAS) Institutes for Advanced Studies.

A. Walther has published ca. 165 papers (h-index 58; > 13300 citations) and has recently been awarded the MPI MINERVA ARCHES award, the Bayer Early Excellence in Science Award (for Materials), the Reimund Stadler Young Investigator Award of the German Chemical Society, a BMBF NanoMatFutur Research Group, as well as the Hanwha-Total IUPAC Young Scientist Award awarded at the biannual IUPAC World Polymer Congress 2018.

Link to the group page: www.walther-group.com
Link to Google Scholar: https://scholar.google.com/citations?user=C80MTEkAAAAJ&hl=en

5 Selected Publications + 2 Review:

1. Review 1: Walther, A.; “From Responsive to Adaptive and Interactive Materials and Materials Systems: A Roadmap” Adv. Mater. 1905111 (2020) (Invited View Point for a special issue on “Interactive Materials”).
2. Review 2: Merindol, R.; Walther, A. “Materials Learning from Life: Concepts for Active, Adaptive and Autonomous Molecular Systems” Chem. Soc. Rev. 46, 5588 (2017). Invited Review for the Chem. Soc. Rev. special issue on “Chemical systems Out of Equilibrium”.
3. Samanta, A., V. Sabatino, T. Ward, A. Walther. Functional and morphological adaptation in DNA protocells via signal processing prompted by artificial metalloenzymes Nat. Nanotechnol. 1856 (2020).
4. Jie, D., Walther, A. ATP-Powered Molecular Recognition to Engineer Transient Multivalency and Self-Sorting 4D Hierarchical Systems Nat. Commun. 11, 3658 (2020).
5. Merindol, R.; Delechiave, G.; Heinen, L.; Catalani, L. H.; Walther, A. “Modular Design of Programmable Mechanofluorescent DNA Hydrogels” Nature Commun. 10, 529 (2019).
6. Heuser, T.; Weyandt, E.; Walther, A. “Biocatalytic Feedback-Driven Temporal Programming of Self-Regulating Non-Equilibrium Peptide Hydrogels” Angew. Chem. Int. Ed, 54, 13258 (2015)
7. Das, P.; Malho, J.-M.; Koshrow, R.; Schacher, F.; Wang, B.; Walther, A.: “Nacre-Mimetics with Synthetic Nanoclays up to Ultrahigh Aspect Ratio” Nat. Commun. 6, 5967 (2015).

Abstract:

Sixty years of academic collaboration and thirty years of commercialization by a network of small businesses have delivered a mature technology of computational materials design and accelerated qualification grounded in the CALPHAD system of fundamental databases now known as the Materials Genome. Two computationally designed aircraft landing gear steels have already been taken to full flight qualification employing this technology. The announcement in 2011 by the US President of a national Materials Genome Initiative acknowledging the reality of this technology has spurred global interest and rapid adoption by US apex corporations. Designed materials with broad market impact now span a range from consumer electronics to space exploration. Integration of DFT methods has provided surface thermodynamic databases for control of interfacial properties, and high-throughput methods have helped expand CALPHAD databases to enable predictive design of HEA systems.

Bio:

Greg Olson is ThermoCalc Professor of the Practice in the Department of Materials Science & Engineering at MIT. He is a co-founder of the multi-institutional NIST-supported CHiMaD Center for Hierarchical Materials Design, Director of its SRG Design Consortium, and a founder of QuesTek Innovations LLC. A member of the National Academy of Engineering, the American Academy of Arts and Sciences, the Royal Swedish Academy of Engineering Sciences, and a fellow of ASM and TMS, he has authored more than 300 publications. He received a BS and MS in 1970 and ScD in 1974 in materials science from MIT and remained there in a series of senior research positions before joining Northwestern University as Professor in 1988, where he was appointed Wilson-Cook Professor of Engineering Design in 1999, W. P. Murphy Professor in 2010, and Professor Emeritus in 2019. Recent awards include the ASM Campbell Memorial Lectureship, the Cambridge University Kelly Lectureship, the ASM Gold Medal, the TMS Morris Cohen Award, and an honorary doctorate from KTH-Stockholm.