Author Archives: SAM

Special Edition of the Materials Colloquium 2020

July, 23rd, 15:00

Zoom

Elsa Olivetti (MIT, Department of Materials Science and Engineering)

Materials have long played a role in transitioning between eras. Now the materials community’s most pressing task is to decarbonize society. For the past several decades, materials science has played a key role in lowering carbon dioxide emissions from the electricity sector through development of renewable energy generation and high performing energy storage technologies. However, outside of the energy sector there remain significant greenhouse gas emissions linked to materials production, particularly in the form of infrastructure and chemicals production. This presentation focuses on the significant challenge of reducing the burden of materials production itself. I will review recent progress in understanding the potential for decarbonization in the materials production sector and describe where and how the material science community can have significant impact.

Overview Materials Colloquium 2020  

Materials Colloquium 2020 - May, 13th, 16:30

Zoom

Shovon Pal (Multifunctional Ferroic Materials)

The goal of observing electrons in motion in real time took a leap forward with the use of short laser pulses. First we use a laser pulse to knock or perturb electrons from their equilibrium position in their respective energy landscape, say for example with optical or infrared energies. This pump pulse will then be followed quickly by a terahertz laser probe that reveals the status of the hole that electron leaves behind or even the various scattering routes that the electrons take while relaxing back. If we do this repeatedly for a couple of times, we can find out exactly how the electron is moving and what it is getting up to. In my talk, I will use this simple ideology on materials with fundamentally different band structures and show what we can learn.

Overview Materials Colloquium 2020

 

Materials Colloquium 2020 - April, 22nd, 16:30

Zoom

Sandra Skjærvø (Mesoscopic Systems)

Artificial spin systems are arrays of nanomagnets that are fabricated through state-of-the-art lithography techniques. The nanomagnets interact through dipolar coupling and, depending on the arrangement of the nanomagnets, the system can order magnetically. With X-ray Photon Correlation Spectroscopy, we aim to understand the evolution of the magnetic order in an artificial spin system with square geometry through the known antiferromagnetic phase transition. Below the phase transition at TN, the system is in a single-domain antiferromagnetic ground state. Upon heating, slow fluctuations in the system lead to striking speckle patterns with distinct features and long life times. The small size and rectangular shape of the array of nanomagnets provides a possible explanation for the distinctness of the speckle patterns, with stripe-like domains nucleating at and propagating from the edges of the array, in line with previous observations.

Overview Materials Colloquium 2020

Materials Colloquium 2020 - April, 1st, 16:30

Zoom

Yaroslav Romanyuk (EMPA Dübendorf)

Thin-film solar cells belong to the so-called second generation of solar cells, whereby a thin semiconductor absorber layer of 1…5 microns is used to fully absorb incoming sunlight. The talk will describe current status and research challenges for three thin-film technologies based on Cu(InGa)Se2, CdTe and organometal lead halide perovskites, which have demonstrated power conversion efficiencies in the 22-25% range. All technologies are being actively investigated at the Laboratory for Thin Films and Photovoltaics at Empa: https://www.empa.ch/web/s207

Overview Materials Colloquium 2020

Yinyin Bao (D-CHAB)

Additive manufacturing (commonly called 3D printing) has attracted great attention due to its powerful ability to create complex 3D geometries with precise microarchitectures. In combination with medical imaging techniques, it might provide enormous opportunities to design customized drug formulations and biomedical devices.1 Among the existing 3D printing techniques, digital light processing (DLP) emerged with high resolution and surface quality, desktop size, designable materials and relatively low cost, which is based on a localized light-initiated photopolymerization process, taking place in a bath containing liquid (macro)monomers and photoinitiators. However, the lack of biocompatible and biodegradable materials suitable for DLP limits their application in the biomedical area, especially for the manufacture of elastic personalized devices.2 As a typical elastic implant, airway stents are designed to simulate the airway anatomy providing palliation of symptoms in patients suffering from central airway obstruction.3 However, the clinical use of commercial one-size-fits-all stents is often constrained by the geometrical mismatching to the complex tracheabronchial anatomy of individual patients,4 this could be changed by personalized 3D printing. We aim at the development of biodegradable polymeric materials for DLP 3D printing with highly tunable mechanical properties, towards the manufacture of personalized airway stents. This work opens new perspectives for developing precise personalized medical devices with biodegradability as well as high mechanical properties by 3D printing.
References
1. Zhao, H.; Yang, F.; Fu J.; Gao, Q.; Liu, A.; Sun, M.; He, Y. ACS Biomater. Sci. Eng. 2017, 3, 3083.
2. Zhang, J.; Xiao, P. Polym. Chem., 2018, 9, 1530.
3. Lee P.; Kupeli E.; Mehta A. C. Clin. Chest Med. 2010, 31, 141.
4. Dutau, H.; Musani, A. I.; Laroumagne, S.; Darwiche, K.; Freitag L.; Astoul P. Respiration 2015, 90, 512.

Overview Materials Colloquium 2020

Guido Panzarasa (Soft and Living Materials)

Living systems can grow bottom-up a huge variety of materials with the highest degree of sophistication and an overall efficiency that remains largely unparalleled by artificial fabrication techniques. Moreover, living materials are adaptive i.e. are able to exist and perform autonomously under dissipative conditions. These features are possible thanks to the ability to control complex reactions networks, carefully organized in spatio-temporal sequences. Filling the gap between state-of-the-art stimuli-responsive materials and living materials requires to combine materials science with systems chemistry. In this way, chemical curiosities such as clock and oscillating reactions become versatile tools to program in time the autonomous and transient self-assembly of organic as well as inorganic building blocks. The design of such ad hoc reaction networks is at the core of my current research efforts. I will show how to “clock” molecules, polymers and metal cations into different structures (from nanoparticles to gels), without the need for external control, and how this approach can pave the way to the development of (almost) living artificial materials.

References:

  1. Panzarasa*, A. Osypova, A. Sicher, A. Bruinink, E. R. Dufresne, Controlled formation of chitosan particles by a clock reaction Soft Matter 2018, 14, 6415–6418 DOI: 10.1039/C8SM01060A
  2. Panzarasa*, Eric R. Dufresne, Impact of in situ acid generation and iodine sequestration on the chlorite-iodide clock reaction Chaos 2019, 29, 071102 (5 pp) DOI: 10.1063/1.5108791
  3. Panzarasa*, T. Sai, A. L. Torzynski, K. Smith-Mannschott, E. R. Dufresne, Supramolecular assembly by time-programmed acid autocatalysis Mol. Syst. Des. Eng. 2020 DOI: 10.1039/c9me00139e
  4. Panzarasa*, A. L. Torzynski, T. Sai, K. Smith-Mannschott, E. R. Dufresne, Transient supramolecular assembly of a functional perylene diimide controlled by a programmable pH cycle Soft Matter 2020, 16, 591-594 DOI: 10.1039/C9SM02026H
  5. C. C. M. Sproncken, B. Gumí-Audenis, G. Panzarasa, I. K. Voets, Two-stage polyelectrolyte assembly orchestrated by a clock reaction ChemSystemsChem 2020 (accepted)

Overview Materials Colloquium 2020

Dear colleagues,

Together with Materials Alumni (http://www.matalumni.ethz.ch/, the association representing the alumni of D-MATL), we have the chance to visit the robotic fabrication lab (RFL) of the NCCR (National Competence Center of Research in digital fabrication) on the campus Hönggerberg. With the special guided tour, the participants will have the chance to learn on various research topics in RFL and see many prototypes of future construction techniques.

The tour will start at 6 pm on January 28th. After the tour (~1 h) we will gather for some Feuerzangenbowle (mulled wine with a rum-soaked sugarloaf lit above it – you will love it ;-) ) and mingle with Materials Alumni and current doctoral students, postdocs and senior scientists of D-MATL.

The guided tour is limited to 30 participants. Please register by writing an email to vvoney@ethz.ch. The participation is free of charge. It will be on a first-come-first-served basis.

Summary:
When: Tuesday, January 28th, 2020, at 6 pm
Where: Campus Info, ETH Hönggerberg (Click the link for Information on how to get there)
What: Tour through the robotic fabrication lab at ETH Hönggerberg, followed by Feuerzangenbowle

We are looking forward to seeing many of you there.

Best regards,
Your SAM team

Arkadiy Simonov (D-MATL, Multifunctional Ferroic Materials)

Prussian blue analogues (PBAs) are a broad and important family of microporous inorganic solids, famous for their gas storage, metal-ion immobilisation, proton conduction, and stimuli-dependent magnetic, electronic and optical properties, The family also includes widely investigated hexacyanoferrate/hexacyanomanganate (HCF/HCM) battery materials. Central to the various physical properties of PBAs is the ability to transport mass reversibly, a process made possible by structural vacancies. In the absence of a better model the distribution of such vacancies was assumed random.

In this talk I would like to present the latest results of analysis of the diffuse scattering from PBA single crystals which show that vacancy show surprisingly strong local ordering. Moreover, the distribution of these vacancies is influenced by crystallization conditions. Our results establish a clear foundation for correlated defect engineering in PBAs as a means of controlling storage capacity, anisotropy, and transport efficiency.

Overview Materials Colloquium 2020