Category Materials Colloquium

Lecture Hall HCI J7, 16:30

Ainoa Guinart Planellas

Complex Materials, D-MATL, ETH Zürich

Light-driven molecular machines drive biological membranes out of equilibrium

Mechanical forces generated by the cytoskeleton and proteinaceous assemblies play a central role in shaping biological membranes during processes such as trafficking, division, and differentiation. Here, we present a strategy to induce membrane curvature by integrating a light-powered synthetic rotary motor into biological membranes. We demonstrate the incorporation and operation of the motor in both supported and free-standing systems, and investigate how membrane confinement influences motor properties, including rotary speed and quantum yield, as well as membrane fluidity and tension. Through systematic studies of motor concentration, cholesterol content, membrane composition, local heating, and singlet oxygen generation, we reveal the complex interplay between motors and lipid bilayers. Importantly, visible-light irradiation drives the system out of equilibrium, enabling on-demand transformations. Overall, this work provides new insight into the dynamic interactions between molecular motors and biological systems, opening avenues toward light-controlled active biomimetic systems.

Stefan Mommer

Macromolecular Engineering, D-MAVT, ETH Zürich

Tough supramolecular hydrogels through CB[8] host—guest complexation

Supramolecular hydrogels have been transformative to material sciences due to their dynamic and tunable properties, relying on reversible non-covalent interactions instead of covalent bonds. This reversibility represents an efficient strategy for energy dissipation, paving the way for tough and robust hydrogels with innovative solutions in load-bearing medical and technological applications. Due to their high binding constants, especially the use of Cucurbit[n]uril (CB[n]) host–guest complexes has become a popular way to mediate gelation of polymer chains. Among its different homologues, CB[8] is able to form multitopic complexes where two guests are bound simultaneously. Consequently, it can host a variety of guest structures and connected to this, the thermodynamically stable complexes are used as cross-links exhibiting a broad range of binding constants. Regarding the structure–property relationship of CB[8]-based hydrogels, it is the binding constant that largely dictates the mechanical properties of the hydrogels. Despite the great potential of CB[8] complexes as highly dissipative cross-links, toughness and hysteresis behavior of tough CB[8] hydrogels for load-bearing applications have remained under-explored. Therefore, we decided to explore the potential of CB[8]-mediated hydrogels as load-bearing materials. In our work, we use homoternary 1:2 host–guest complexation of a new series of customizable monomers based on diallyl benzyl methyl ammonium chlorides (DABMAC) to mediate cross-links in polymer networks. We optimize our formulations to obtain hydrogels that exhibit high stretchability, toughness and self-recoverability, while maintaining an overall water content of ~88%.

Nicola Spaldin

Materials Theory, D-MATL, ETH Zürich

Hunting for Hidden Order

Most magnetic materials, phenomena and devices are well described in terms of the magnetic dipoles arising from the spin of their constituent electrons. There is mounting evidence, however, of intriguing magnetic behaviors that can’t be explained in terms of electron spin dipole moments; these behaviors are often attributed to “hidden order” since their origin is difficult to decipher with conventional experimental probes. I will show how computer simulations can help us to hunt for hidden magnetic order, and in turn to explain or predict weird magnetic properties.

Lecture Hall HCI J6, 16:30

Tatiana Akhmetshina

Laboratory for Metal Physics and Technology, ETH Zürich

Smart Metals in Medicine: Designing Implants that Support and Disappear

Millions of patients undergo secondary surgeries to remove permanent metal implants after fracture healing. Biodegradable magnesium alloys offer temporary support that dissolves safely in the body. Existing systems rely on complex compositions with unclear health impacts and limited understanding of degradation mechanisms. This work presents chemically simple Mg-Ca alloys (< 1 wt.% Ca) that achieve unprecedented mechanical performance while maintaining complete biodegradability. Through advanced processing and innovative 3D nanoscale imaging, we visualized the degradation lifecycle and identified key mechanisms governing material behavior. These alloys demonstrate superior strength-to-composition ratios and controlled degradation compared to current medical-grade materials. This research provides practical guidelines for implant development and new methods to predict long-term performance, accelerating translation of biodegradable metals into clinical applications.

Dragan Damjanovic

Laboratory for Ferroelectrics and Functional Oxides, EPFL

Defects, Symmetry-Breaking and Multi-property Coupling in Complex Materials

Piezoelectricity and pyroelectricity are typically linked to noncentrosymmetric crystal structures, but their thermodynamic definition only requires the macroscopic sample to be noncentrosymmetric or to possess a polar axis. This explains why amorphous electrets can show these effects despite lacking long-range crystalline order. An interesting question is whether materials with long-range centrosymmetric crystal structures can still display piezoelectric or pyroelectric behavior. Thermodynamically the answer is simple, yet such reports remain surprising, especially when the effects are large, suggesting nontrivial mechanisms. Here, we discuss emergent pyroelectricity and piezoelectricity in doped CeO₂ and in various perovskite oxides and halides with nominally centrosymmetric structures. In several cases, the observed polarization originates from inhomogeneous distributions of charged defects, such as oxygen vacancies, whose arrangement can be controlled or switched by external fields. This defect engineering also opens possibilities for multi-property coupling, such as electro-chemo-photo-thermo-mechanical responses, which will be discussed in the talk.

Lecture Hall HCI J7, 16:30

Prof. Arkadiy Simonov

Laboratory for Disordered Materials, ETH Zürich

Gas Storage in Disordered Materials

Gas storage materials are typically studied through average structure measurements, but this approach misses important structural changes during material activation and gas cycling. Using diffuse X-ray scattering on Prussian Blue materials – frameworks previously considered stable and straightforward for hydrogen storage – we reveal hidden structural transitions that occur during gas storage processes. Dehydration causes a significant reorganization of the local structure, creating new transport pathways through the material, while further structural modifications occur during gas absorption and desorption cycles. These changes, which remain invisible to average structure measurements yet significantly affect storage performance, demonstrate the importance of examining local structure during gas storage processes for developing better storage materials.

Dr. Quinn Besford

Leibniz Institute of Polymer Research Dresden

Leveraging Conformationally-Fluorescent Polymers for In Situ Sensing of Interfacial Phenomena

Spatially resolving interfacial stimuli can allow us to better understand physicochemical processes. Towards this goal, we develop ways of integrating Förster resonance energy transfer (FRET) chemistry into stimuli-responsive polymer architectures, such that FRET output (i.e., spectral shift in output fluorescence) reflects polymer chain conformation. Using FRET, we can spatially resolve conformation by confocal microscopy methods, with high spatiotemporal resolution. In this talk, I will discuss strategies to integrate FRET into functional polymers, and how we can examine the responsiveness of the polymers for understanding physicochemical processes. Specifically, these systems are used to study surface wettability, localized changes in pH, resolving ion fluxes, and micro-to-nano structure in secondary matrices. Our systems provide a non-invasive optical measure of changing surface conditions, which holds great promise for identifying processes in real-time.

Lecture Hall HCI J6

Dr. Sebastian Kahlert

Office of ETH Sustainability, ETH Zürich

ETH Sustainability and the ETH Net Zero Programme

At ETH Zurich, we are working to significantly reduce our greenhouse gas emissions by 2030. ETH Net Zero is a task for which we are jointly responsible. The “ETH Net Zero” programme bundles impact-oriented activities for the years 2024 to 2030 to reduce all climate-​relevant emissions on campus as well as in teaching and research at ETH as far as possible.

In this talk, Sebastian Kahlert, the programme manager, will give an overview of activities within the Programme and share ways on how you can contribute and participate.

Prof. Moran Bercovici

Laboratory for Fluid Technologies, Technion

Fluidic Shaping – from the lab to the international space station

Theoretical and experimental work is presented on leveraging the basic physics of liquid-fluid interfaces for fabrication of a wide range of high-quality optical components, without the need for any mechanical processing. The theoretical and experimental aspects of several mechanisms that allow such ‘Fluidic Shaping’ are discussed – from photoactivated Marangoni flows that enable dynamic programmable thin-film deformations, to passive shaping under neutral buoyancy where pinning boundary conditions drive the liquid volume to a desired minimum energy. Finally, our collaboration with NASA on the use of Fluidic Shaping for the creation of future giant space telescopes is discussed, and our zero-g experiments in parabolic flights and on board the international space station are presented.

Lecture Hall HCI J4

Dr. Hyun Suk Wang

Laboratory for Polymeric Materials , ETH

Depolymerization of Commercial Polymethacrylates Triggered by Visible Light

The reversion of vinyl polymers with C–C backbones to their monomers represents an ideal path to alleviate the growing plastic waste stream. However, depolymerizing such stable materials remains a challenge, with state-of-the-art methods relying on “designer” polymers [1-2] that are neither commercially produced nor suitable for real-world applications. Here, we report a main-chain-initiated, visible-light-triggered depolymerization directly applicable to commercial polymers containing undisclosed impurities (e.g. comonomers, additives, dyes).[3] By in-situ generation of chlorine radicals directly from the solvent, near-quantitative (>98%) depolymerization of polymethacrylates could be achieved regardless of their synthetic route (e.g. radical or ionic polymerization), end-group, and molecular weight (up to 1.6 million Da). The possibility to perform multi-gram scale depolymerizations and confer temporal control renders this methodology a versatile and general route to recycling.

1. Wang, H.S.; Truong, N.P.; Pei, Z.; Coote, M.L.; Anastasaki, A.; Reversing RAFT Polymerization: Near-Quantitative Monomer Generation Via a Catalyst-Free Depolymerization Approach. J. Am. Chem. Soc. 2022, 144, 4678–4684
2. Wang, H.S.; Parkatzidis, K.; Junkers, T.; Truong, N.P.; Anastasaki, A.; Controlled radical depolymerization: Structural differentiation and molecular weight control. Chem 2024, 10, 388-401
3. Wang, H.S.; Agrachev, M.; Kim, H.; Truong, N.P.; Choi, T.-L.; Jeschke, G.; Anastasaki, A.; Visible-Light-Triggered Depolymerization of Commercial Polymethacrylates. Science 2025, Accepted

Dr. Tenorio Tunas Maria

Laboratory for Magnetism and Interface Physics, ETH

1D and 2D graphene nanoarchitectures with atomic precision: from on-surface synthesis to quantum electronic properties

Bottom-up synthesis has proven to be a highly efficient method to build graphene nanoarchitectures with atomic precision, giving rise to tunable quantum electronic properties. The most illustrative example is the vast array of graphene nanoribbons (GNRs) that have been synthesised almost à la carte. However, achieving greater structural complexity and scaling up to two dimensions remains a significant challenge.

The on-surface synthesis of 2D nanoporous graphene (NPG) [1] marked a breakthrough, demonstrating the feasibility of growing a graphene-based monolayer nanostructure with semiconducting and anisotropic electronic properties, while exhibiting long-range order and uniformly distributed array of atomically precise nanopores.

Here, we present novel synthetic approaches to control the pore shape, size [2], and the dopant distribution [3] of NPG with atomic precision, while preserving the long-range order. This will cover from assessing the on-surface synthesis of doped GNR to 2D NPGs and porous GNRs. Regarding dopant content [3, 4], we demonstrate the stability of heteroatom-containing pores and the ultimate fabrication of a lateral superlattice of heterojunctions, where the junction is reduced to the carbon-carbon bond distance. This novel material exhibits in-gap tunnelling states and interface quantum dipoles, which further refine the heterojunction’s characteristics. For pore size and shape tunability [2, 5], we show that different phenylene-type bridge configurations can lead to different electronic lateral coupling of the NPG components, enabling or suppressing the quantum transport.

Bond-resolved Scanning Tunneling Microscope (STM) has been the tool used to inspect the nanopore characteristics (Figure 1) by functionalising the tip with a single CO molecule. Scanning Tunneling Spectroscopy (STS) has provided key insights into the quantum electronic properties emerging from these novel 2D nanoporous graphene structures, which have been simultaneously corroborated by DFT ab-initio calculations. Our results reflect that the rational design of both specific molecular precursors and reaction pathways can lead to the formation of long-range and multifunctional NPGs.

Figure 1: Bond-resolved constant height Scanning Tunnelling Microscope image of two covalently coupled GNRs: a nitrogen-doped one (left) and a carbon pristine one (right), showing the formation of nanopores at the junction. (STM conditions: 8 nm X 4 nm, 3 mV)

1. C.Moreno M.Vilas-Varela, B.Kretz, A.Garcia-Lekue, M.V.Costache, M.Paradinas, M. Panighel, G.Ceballos, S.O.Valenzuela, D.Peña, A.Mugarza, Science, 360, 199-203 (2018); C. Moreno, M. Panighel, M. Vilas-Varela, G. Sauthier, M. Tenorio, G. Ceballos, D. Peña, A. Mugarza, Chem. Mater. 31, 331-341 (2019)
2. C. Moreno, X. Diaz de Cerio, M. Vilas-Varela, M. Tenorio, A. Sarasola, M. Brandbyge, D. Peña, A. García-Lekue, A. Mugarza, JACS, 145, 8988-8995 (2023)
3. M. Tenorio, C. Moreno, P. Febrer, J. Castro-Esteban, P. Ordejón, D. Peña, M. Pruneda, A. Mugarza, Advanced Materials, 19 (2022)
4. M. Tenorio, C. Moreno, M. Vilas-Varela, J. Castro-Esteban, P. Febrer, M. Pruneda, D. Peña, A. Mugarza, Small Methods 8 (2023)
5. C. Moreno, X. Diaz de Cerio, M. Tenorio, F. Gao, M. Vilas-Varela, A. Sarasola, D. Peña, A. García-Lekue, A. Mugarza (2024)

The 7th edition of the Materials Colloquium 2024 will take place next Tuesday November 5th, at 4.30 PM in HCI G3.

It is a common belief that damage caused by freezing is due to water’s expansion as it freezes. However, in most soft materials, this expansion actually plays a rather insignificant role. Instead, freezing damage is typically caused by the (far less well-known) process of ‘cryosuction’, where ice crystals grow by sucking nearby water towards them. This suction can lead to huge amounts of ice expansion inside soft, wet materials. We study freezing damage with an experimental system that allows us to directly image individual ice crystals growing inside soft, wet materials. The results reveal a range of insights — for example, we find that the freezing damage is surprisingly similar to the damage that arises during the drying of wet materials. Furthermore, unexpected factors, such as the polycrystallinity of ice, can play an important role in the freezing process.

Marianne Liebi (Laboratory for X-ray Characterization of Materials, EPFL)

Imaging with X-ray scattering contrast for the characterization of hierarchical material structure

Microscopy in scanning mode allows to image different contrasts from the sample, by probing not only absorption and phase contrast of the sample but for example a full X-ray fluorescence spectrum or a 2D scattering pattern. Small- and wide-angle X-ray scattering (SAXS/WAXS) imaging is in particular valuable for heterogeneous samples, in which structural elements in the nano- or Ångström-scale change over macroscopic length scales, thus several millimeters or centimeters. The scattering patterns provide statistical information in each scan point, making this method complementary to high-resolution imaging techniques. The information extracted from each scattering pattern can be used to create images with different contrast, such as density of nano-scale features or orientation of nanostructures. These methods can also be combined with computed tomography to study the inside of three-dimensional samples in tensor or texture tomography. A range of applications will be shown from biological tissues to various soft-matter systems.

In-person in HCI J4:

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Elastic Microphase Separation Produces Bi-continuous Materials

Carla Fernández-Rico (Laboratory for Complex Materials — D-MATL)

Phase separation is a fascinating physical process that is not only responsible for the internal organization of living cells but also a promising tool for structuring soft materials. The central challenge in making meso-structured materials via phase separation is the lack of structural control at length scales beyond the macromolecular scale. In this talk, I will introduce Elastic MicroPhase Separation (EMPS) as a route to create bi-continuous structures in the scale of hundreds of nanometers inside elastomeric networks. I will present the analysis of the microstructure, phase equilibria, and kinetics of the system, and show how it features aspects of both nucleation and growth and spinodal decomposition. Finally, I will demonstrate the potential our approach by toughening polymeric materials, and making bi-continuous structures with controlled structural and anisotropic gradients. 

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Unravelling Plasmonic Photoelectrochemistry at Macro- and Micro-scales

Giulia Tagliabue (Laboratory of Nanoscience for Energy Technologies, EPFL)

In the last decade, plasmonic and dielectric nanoantennas have revolutionized light manipulation and control at the nanoscale. Interestingly, hot carriers and photoluminescence in metals have opened new pathways for controlling photo(electro)chemical processes and monitoring temperatures. Yet, fundamental questions remain about the microscopic details of these complex light-matter interactions. We have recently developed a well-controlled experimental platform based on ultrathin monocrystalline gold flakes and scanning electrochemical microscopy that, in combination with theory, enables deeper insight into light absorption and emission processes as well as photochemical transformations. In particular, I will present micro-scale photoelectrochemical measurements clarifying the interplay of hot carrier generation/transport and quantifying the injection probability of high-energy d-band holes at the metal-electrolyte interface, connecting it to the ultrafast dynamics of these carriers in monocrystalline metals. Overall, this microscopic insight is critical to advance the design of plasmonic-based energy devices. I will also show complementary results unraveling the origin of luminescence in gold and how crystallinity improves hot carrier dynamics and transport.

In-person in HCI G4:

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Machine Learning for the Inverse Design of (Meta-)Materials

Dennis M. Kochmann (Mechanics and Materials Lab – D-MAVT)

Multiscale material modeling has two primary goals: (i) understanding and predicant a material’s properties based on its small-scale architecture, and (ii) identifying those small-scale structural features that enable us to control and optimize a material’s properties and performance. Owing to the rise of additive manufacturing, metamaterials (or architected materials) have emerged as a special class of artificial materials with interesting or tunable properties, and as a new playground for computational modeling. While the forward problem (i) has produced many successful modeling techniques across scales, the inverse problem (ii) has remained a challenge: how do we design (meta-)materials with target properties? At the core of this challenge are the abundant design and property spaces, as well as the fact that the map from structure to properties cannot be inverted. Here, we will discuss how in recent years machine learning has offered new opportunities for the inverse design of (meta-)materials through generative models that predict metamaterial architectures with extreme, peculiar, or as-designed mechanical properties

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Harnessing Size Effects: Where Nanostructures Meet Additive Manufacturing

Rebecca Gallivan (Laboratory for Nanometallurgy – D-MATL)

Nanostructured materials promise to unlock new functionality that can address modern challenges in electronics, health, and infrastructure. However, to fully hardness the power of size-based effects, we need to develop new methods for designing microstructurally complex and heterogeneous nanostructures. Furthermore, deep fundamental understanding of designed nanoscale materials is critical for bringing these tools to the materials engineers of tomorrow. Using novel nanoscale additive manufacturing and nanomechanical techniques, we will explore new pathways for nanoscale materials design and investigate the emergingmaterials behaviors that arise at the intersection of geometric and microstructural size-effects. Insights will focus on beginning to untangle the intricate roles of processing and microstructure in advancing nanoscale materials performance.