Taking a historical snapshot of chiral plasmonics, after discovery in the 19th century and becoming more important in the 20th century for pharmacological and biological applications, in the early 2000s, twisted plasmonic nanostructures revealed strong chiroptical responses. However, their fabrication remained complex and limited. The 2010s introduced enabling tools such as DNA origami, colloidal self-assembly, and metamaterials, allowing precise control over chiral plasmonic architectures—but mostly within specialized labs.

The chiral plasmonic community experienced a major shift in the late 2010s, driven by easier access to chirality-related technologies: compact circularly polarized light (CPL) sources and affordable CD spectrometers made chiral plasmonics widely accessible. A recent visit to the Gold 2025 conference (San Sebastian, May 2025) revealed how dramatically the plasmonics community refocused from purely morphological anisotropic materials to nanomaterials with explicit chiral asymmetry. Across sessions – whether on sensing or catalysis – “chiral” appeared repeatedly in presentation titles.

The recent Focus article by Santiago and team published in Materials Horizons brings a new paradigm into fabrication techniques compared to previous approaches: what if chirality could be written post-synthetically by light? Their last years studies and other’s referred in this article, centering on light-to-matter chirality transfer, presents a conceptual leap. By exposing initially achiral plasmonic nanostructures to CPL, one can induce asymmetric surface transformations—effectively allowing the electromagnetic field to sculpt chirality dynamically. This “optical handwriting” of symmetry is not just elegant—it’s potentially more scalable, adaptive, and informative.

(a) Schematic diagram of the model for continuous CPL illumination of a colloidal Au nanocube, with the effective response being an average of six different directions for the propagation of light, and map of the differential rate of intraband hot carrier excitation under both polarizations of CPL. (b) Scheme of transformation of achiral nanobars into chiral ones in a colloidal suspension, driving galvanic replacement reaction CPL illumination of colloidal Au@Ag nanoprisms, alongside 3D models of the resulting geometries (obtained with TEM tomography), TEM images of the chiral bimetallic structures, and dissymmetry factor of the sample after illumination with CPL at 660 nm. (c) Geometrical analysis of the tomographic reconstruction of one of the resulting chiral structures (in blue), together with its mirror image (in red). Image and caption reproduced from Figure 12 (DOI= 10.1039/D5MH00179J) with permission from the Royal Society of Chemistry.

What makes this emerging direction so promising? First, light-induced chirality eliminates the need for chiral templates or reagents, granting full spatial and temporal control through illumination parameters – angle, polarization, phase structure, intensity. Second, the process doesn’t just modify geometry – it can modulate surface chemistry, reaction kinetics, or even local field helicity. It’s an enabler of materials previously considered inaccessible by static synthesis methods.

Despite these promises, the critical questions is a mechanistic pathways of chirality inscription under CPL. What’s the role of photothermal vs. hot-carrier effects? How does local field enhancement affect enantioselective growth? Quantitative metrics – such as dissymmetry factor (g) and CD spectral shifts—must be systematically correlated with structural evolution, not just endpoint characterization. Or even can chirality of these plasmonic structures transferred to chiral organic molecules? There is still a wide room for investigations.

To find out more, please read:

Light-to-matter chirality transfer in plasmonics
Eva Yazmin Santiago, Muhammad Irfan, Oscar Ávalos-Ovando, Alexander O. Govorov, Miguel A. Correa-Duarte and Lucas V. Besteiro
Mater. Horiz., 2025, DOI: 10.1039/D5MH00179J

About the blogger

Dr Olga Guselnikova is a member of the Materials Horizons Community Board. She joined the Center for Electrochemistry and Surface Technology (Austria) to work on functional materials as a group leader. Dr. Guselnikova received her PhD degree in chemistry from the University of Chemistry and Technology Prague (Czech Republic) and Tomsk Polytechnic University (Russia) in 2019. Her research interests are related to surface chemistry for functional materials. This means that she is applying her background in organic chemistry to materials science: plasmonic and polymer surfaces are hybridized with organic molecules to create high-performance elements and devices.

To combat climate change, we must reduce carbon footprints either through waste reduction or renewable energy. Plastic waste is a significant challenge, with millions of tons ending up in landfills and oceans each year. Thus, it is of immense importance to reduce or recycle plastic waste, or even convert it to useful materials. In a recent study, Z. Qiang et al. show how upcycled plastics, like polyethylene and polypropylene, can be converted into energy-efficient heating elements for clean hydrogen production, tackling both waste reduction and recycling issues simultaneously (Illustrated in Figure 1A). The key innovation in this study lies in transforming discarded plastic into a special kind of carbon material by a combination of techniques, including 3D printing, crosslinking, and pyrolysis (a high-heat process that breaks down materials) to turn plastics into a highly efficient heating element (Figure 1B). The plastic waste is first printed into 3D structures, then chemically treated to make it stronger. Finally, it’s heated to the point where it becomes carbon. This carbon material can then be used as both a catalyst support and a heater in ammonia decomposition for producing hydrogen without harmful emissions (Figure 1C). This simple carbon-based Joule heater heats up when electricity passes through it and is a more efficient method than traditional convection heaters, while offering quicker start-up and shutdown times. That’s a game-changer when it comes to making hydrogen production faster and more energy-efficient.

Figure 1: (A) Illustration demonstrating the upcycling of recycled mixed polyolefin waste to carbon-based Joule heaters for hydrogen production. (B) Mixed waste compounded into 3D-printing filament, and FFF-printed into structured parts turning into structured carbon and connected to a power source to demonstrate Joule heating capabilities. (C) Waste-derived carbons impregnated with Ru-based catalysts for Joule heating-enabled NH3 decomposition for hydrogen production. (D) The global warming impact of furnace heating and Joule heating for ammonia decomposition at different temperatures. (E) The global warming impact of ammonia decomposition by Joule heating (blue bars) versus conventional furnace heating (red line) for various energy sources. Reproduced from DOI: 10.1039/d4mh01755b with permission from the Royal Society of Chemistry.

So basically, the Joule heating isn’t just about generating heat—it’s about doing it in a cleaner, smarter way. Traditional methods of heating can be energy-hungry and slow but using electricity to directly heat materials through Joule heating is much more efficient. In the study, this improved heating method sped up the ammonia decomposition process, allowing for faster hydrogen production. Even better, the process also reduces carbon emissions and energy use compared to conventional methods (Figure 1D, E). That means we can make hydrogen in a cleaner, more sustainable way, helping to reduce our reliance on fossil fuels. The exciting thing about this study is a double win for the planet. On one side, it helps address the massive problem of plastic waste by turning it into something useful. On the other side, it helps create hydrogen, a clean energy source to power everything from vehicles to industrial processes, without any harmful emissions, which paves the way towards zero carbon footprint.

It will be more interesting to see if this approach could also be used in other industries beyond hydrogen production. For instance, replacing the old, carbon-intensive heating systems used in manufacturing with these waste-derived Joule heaters could save massive energy consumption and reduce enormous emissions. Therefore, this research is a big step to address the real-world problem of waste, which will be no longer a problem, but a resource. By linking energy production with material recycling, we can close the loop on waste and make industries cleaner and more efficient. However, it would be preliminary to expect its use at larger scale in various energy sectors. Challenges like ensuring consistent carbon material properties at large scale, long-term thermal stability under high temperatures, and seamless integration with existing hydrogen production systems could be challenging.

To find out more, please read:

Upcycling of mixed polyolefin wastes to 3D structured carbon Joule heaters for decarbonized hydrogen production
Anthony Griffin, Jiachun Wu, Adam Smerigan, Paul Smith, Gbadeoluwa Adedigba, Rui Shi, Yizhi Xiang and Zhe Qiang
Mater. Horiz., 2025, Advance Article

About the blogger

Dr. Shahid Zaman is postdoctoral fellow at the Hydrogen Research Institute, University of Quebec Trois-Rivières (UQTR), Canada, and a member of the Materials Horizons Community Board. He completed his Ph.D. in Material Physics and Chemistry from Huazhong University of Science and Technology in 2021. His research focuses on the development of nanomaterials for electrocatalysis, particularly in proton exchange membrane fuel cells and water electrolyzers.

3D printing has revolutionized the production of polymer-based materials, with the development of numerous printing techniques that continuously enhance speed, resolution, and accessibility. Among the most significant advancements is light-based 3D printing, which utilizes photopolymerization reactions to solidify inks, offering precise spatiotemporal control over the printing process. However, light-based 3D printing primarily relies on uncontrolled polymerization of (meth)acrylate and epoxide monomers/ cross-linkers, which yield non-functional, non-recyclable materials. To fully exploit the potential of 3D printing, there is growing interest in integrating advanced chemistries, such as dynamic chemistry, that enable the fabrication of functional materials capable of post-printing modifications in shape, properties, and functionality. Most polymer-based objects created through current 3D printing techniques cannot be chemically recycled due to the chemical inertness of the materials and the irreversible polymerization processes involved. Thus, it is imperative to incorporate new chemistries into 3D printing that enable the fabrication of advanced, functional, and chemically recyclable materials at the end of their lifecycle.

In a recent work by Du Prez and Nguyen, a closed-loop 3D printing process utilizing dynamic chemistry was reported. The authors synthesized an acrylate photocurable polymeric material based on dynamic β-amino ester cross-linkers, which can be used as an ink for 3D printing. Importantly, this material can undergo decross-linking via a transesterification reaction, resulting in the depolymerization of the formed polymer network. This process is not only reversible, enabling the making and unmaking of polymers, but it also operates under highly appealing and relatively mild conditions.

Figure 1: a) Chemical overview of the polymerization and depolymerization reactions of the dynamic network and b) closed-loop 3D printing. Image reproduced from DOI: 10.1039/D4MH00823E with permission from the Royal Society of Chemistry.

The team first synthesized an acrylate-terminated β-amino ester-containing cross-linker, which serves as a building block for the formation of a dynamic polymer network. This cross-linker was prepared via a one-step aza-Michael addition reaction. The process is straightforward and utilizes commercially available reagents, making the material easily adaptable for other researchers. These low-molecular-weight diacrylate polymers undergo photo-induced free radical polymerization, resulting in the formation of a dynamic polymer network.

This dynamic nature of the polymeric network enables thermomechanical reprocessing of the material. To demonstrate this aspect, the authors used compression molding (at 150 °C under 2 tons of pressure for 30 minutes) for reprocessability. The recycling procedure was repeated three times, with the material showing a slight increase in shear modulus and activation energy, while maintaining stable thermal properties and chemical integrity. The increase in temperature results in a reduction of cross-link density, demonstrating the role of dissociative exchange via (retro) aza-Michael addition. In contrast, polymeric networks without dynamic bonds did not exhibit any reprocessability, highlighting the promise of dynamic chemistry in enabling reprocessable materials.

In the next step, to demonstrate more advanced chemical recycling of this dynamic network, the team employed another reaction (transesterification) using a commercially available methacrylate with a hydroxyl moiety (hydroxyethyl methacrylate) as a decross-linker. The hydroxyl group of this functional methacrylate reacts with the β-amino ester, resulting in the decross-linking of the network and its depolymerization. This reaction is temperature-dependent and requires an optimized amount of decross-linker to achieve a high depolymerization yield. Notably, the depolymerization reaction proceeds without the need for any catalyst or solvent, making the procedure even more appealing. Upon depolymerization of the polymer network, the resulting mixture consists of methacrylate-terminated compounds, as confirmed by electrospray ionization mass spectrometry. These compounds can be further employed for another cycle of photo-curing, enabling the development of curable-depolymerizable dynamic materials.

In the final part, the team demonstrated the translation of this concept into closed-loop 3D printing using the dynamic photocurable resin. Multiple printing cycles were performed with recycled photocurable resin to assess the repeatability of this procedure. The resulting samples exhibited consistent shapes and appearances for at least three cycles, thus demonstrating repeatable printability after chemical recycling.

Overall, this study elegantly combines fundamental aspects of dynamic polymer chemistry and its application in 3D printing, further enhancing interest in dynamic chemistry for both functional and recyclable materials.

To find out more, please read:

Direct restoration of photocurable cross-linkers for repeated light-based 3D printing of covalent adaptable networks
Loc Tan Nguyen and Filip E. Du Prez
Mater. Horiz., 2024, DOI:10.1039/D4MH00823E

About the blogger

Dr. Kostas Parkatzidis is a Swiss National Science Foundation Postdoc Fellow in the group of Professor Zhenan Bao at Stanford University (United States), working on the molecular design of polymer-based skin-inspired materials for various applications. Kostas obtained his PhD from ETH Zurich (Switzerland) under the supervision of Professor Athina Anastasaki where he focused on the development of advanced polymer synthesis and chemical recycling methodologies. He also holds MSc in Organic Chemistry and BSc in Materials Science and Engineering obtained from the University of Crete (Greece). Since 2023, Kostas has served as a Materials Horizons Community Board member.