Terahertz (THz) radiation is rapidly gaining attention for applications in biomedical diagnostics, security, and wireless communication. Polymers play a central role in advancing THz technologies, as they are ideal for lenses, filters, waveguides, and metasurfaces. However, material selection is driven by commercial availability rather than by the rational design of their composition, and progress is hindered by the limited availability of polymers that combine low THz losses with high printability. To address this problem, the relationship between polymer composition and THz transparency in photocurable resins is here investigated, establishing practical guidelines for tailoring THz response through resin composition. A comprehensive framework is developed to predict THz properties based on key structural features, including heteroatoms, cyclic structures, secondary forces, and the carbon-to-oxygen (C/O) ratio. In particular, (meth)acrylic resins with aliphatic backbones exhibit predictable behavior, enabling the estimation of their THz response directly from the C/O atomic ratio. Using the best-performing formulations, photonic crystals for THz modulation were fabricated via digital light processing (DLP) 3D printing. These devices are used to demonstrate how geometric parameters, fabrication precision, and material properties influence the THz devices' response. Comparisons between THz-optimized formulations and commercial resins highlight the importance of combining high printability and THz transparency in the fabrication of functional devices, demonstrating that proper resin design enables the decrease of the absorption coefficient up to 5 cm-1 at 1THz (vs 19-30 cm-1 of commercial resins usually employed for 3D-printed THz devices), maintaining a sufficient printability, resulting in an extension of the range of controllable response of the photonic crystals up to 2 THz, well beyond the sub-0.5 THz limit typically reported in the literature for similar structures. This material-driven approach establishes a rational pathway for designing polymers tailored for THz applications while enabling the fabrication of technologically relevant devices with accessible and low-cost 3D printing.

Magnetic fields are increasingly used in 4D printing to program matter across multiple length scales, enabling control over both macroscopic structures and nanoscale particle organization. However, their integration into additive manufacturing remains limited by compatibility constraints—such as interference with extrusion or optical access—and the inherent challenge of generating spatially resolved, dynamic magnetic fields. In this work, a digital light processing 3D printing method is introduced that directly encodes programmable magnetic anisotropy during fabrication. By formulating a photocurable resin with magnetic nanoparticles and liquid crystal monomers, composite structures are fabricated that respond to both magnetic and thermal stimuli. A hybrid magnetic system—combining a nested Halbach array with a coaxial coil placed in its inner cavity—enables real‐time, 3D control of magnetic fields (in both direction and intensity) during the printing process. This approach enables the alignment of liquid crystal mesogens, magnetic fillers, and the formation of vertically oriented nanoparticle chains. The resulting materials exhibit direction‐dependent actuation, shape reconfiguration, and selective conductivity, demonstrating a versatile platform for creating multifunctional and multi‐stimuli‐responsive devices.

Emerging as a revolutionary strategy to fabricate dynamic three dimesional (3D) structures, 4D printing (4DP) mainly refers to printed materials capable of changing form over time when exposed to a predetermined stimulus. Nevertheless, the 4D concept can be extended beyond shape-morphing, by including also changes in the properties and/or functionalities of printed materials over time. To this end, this work explores the 4DP of multifunctional nanocomposites that can adapt to different application scenarios exploiting the stimuli-activable properties of two functional nanofillers embedded into the polymeric matrix. In particular, a photocurable system loaded with both Fe3O4 nanoparticles (NPs) and AgNO3, as precursors for the in situ photo-induced generation of Ag NPs, is used for the digital light processing of magnetic nanocomposites with integrated electrical and antibacterial functions. The composition of formulations is designed to both optimize their printability and maximize the magneto-responsiveness and the electrical conductivity and/or antibacterial activity of the printed objects, given by Fe3O4 and Ag NPs, respectively. Finally, it is shown that the functional responses of the nanocomposites can be activated individually or in combination, which may be of particular interest for the fabrication of smart multifunctional devices with potential applications ranging from soft electronics to biomedicine. 4D printed multifunctional polymeric magneto-electric and magneto-antibacterial devices are fabricated employing vat photopolymerization 3D printing, exploiting the properties of both Fe3O4 embedded and in situ generated Ag nanoparticles. The functional responses of such materials can be successfully activated individually or synergistically, envisaging potential applications from soft electronics to biomedicine. image

The removal of oil from water is a worldwide challenge that must be faced to avoid irreversible marine habitat destruction. A novel fast and simple technique to obtain polydimethylsiloxane (PDMS) membranes is developed using the photopolymerization technique. The high reactivity of the acrylated PDMS formulation toward photo-induced free radical polymerization is assessed via the differential scanning photo-calorimetry (photo-DSC) technique. Two different membranes dense or porous are developed and investigated. Porous membranes, having 100-200 mu m as pore size, are obtained using a low-cost environmentally friendly sodium chloride template. Thanks to the hydrophobic/oleophilic intrinsic characteristic of PDMS, the UV-cured membranes can selectively remove dodecane, selected as the target oil, from water. The dodecane sorption capability of both membranes is investigated and compared. Moreover, the membranes can be easily reused since the adsorbed oil can be recovered by simply compressing the membrane. Those PDMS sorbents show high mechanical stability after five adsorption/desorption cycles.

Surface-enhanced Raman optical activity (SEROA) has been extensively investigated due to its ability to directly probe stereochemistry and molecular structure. However, most works have focused on the Raman optical activity (ROA) effect arising from the chirality of the molecules on isotropic surfaces. Here, we propose a strategy for achieving a similar effect: i.e., a surface-enhanced Raman polarization rotation effect arising from the coupling of optically inactive molecules with the chiral plasmonic response of metasurfaces. This effect is due to the optically active response of metallic nanostructures and their interaction with molecules, which could extend the ROA potential to inactive molecules and be used to enhance the sensibility performances of surface-enhanced Raman spectroscopy. More importantly, this technique does not suffer from the heating issue present in traditional plasmonic-enhanced ROA techniques, as it does not rely on the chirality of the molecules.

The revolution of 4D printing allows combining smart materials to additive processes to create behavioral objects able to respond to external stimuli, such as temperature, light, electrical, or magnetic fields. Here, a modified commercial digital light processing (DLP) 3D printer is used to obtain complex macroscopic remotely controlled gear‐based devices. The fabrication process is based on the printing of magnetoresponsive polymers containing in situ self‐assembled microstructures, i.e., composed of oriented chains of Fe 3 O 4 nanoparticles (NPs). First, it is demonstrated that magnetoresponsive hammer‐like actuators with different stiffness can be printed allowing both pure rotation or/and bending motions. Then, the microstructure to create a magnetoresponsive gear is exploited. In particular, this work shows that they can be successfully used to transfer torque to other gears, thereby converting a rotation movement into linear translation. Finally, it is demonstrated that magnetoresponsive gears can also be combined with other nonmagnetic elements to create complex assemblies, such as gear‐trains, linear actuators, and grippers that can be remotely controlled.

We use ultrafast electron diffraction to study the out-of-equilibrium dynamics of the charge density wave (CDW) phase transition in GdTe3, a quasi-two-dimensional compound displaying a unidirectional CDW state. Experiments were conducted at different incident fluences and different initial sample temperatures below Tc. We find that following photo-excitation, the system undergoes a non-thermal ultrafast phase transition that occurs in out-of-equilibrium conditions. The intrinsic crystal temperature was estimated at each time delay from the atomic thermal motion, which affects each Bragg peak intensity via the Debye Waller factor. We find that the crystal temperature stabilizes with a 6 ps timescale in a quasi-equilibrium state at temperature T q . e .. We then relate the recovery time of the CDW and its correlation lengths as a function of T q . e .. The charge density wave is suppressed in less than a picosecond while its recovery time increases linearly with incident fluence and initial temperature. Our results highlight that the dynamics is strongly determined by the initial sample temperature. In addition, the transient CDW phase recently observed along the transverse direction in LaTe3 and CeTe3 is not observed in GdTe3.

When a lipid membrane approaches a material/nanomaterial, nonspecific adhesion may occur. The interactions responsible for nonspecific adhesion can either preserve the membrane integrity or lead to its disruption. Despite the importance of the phenomenon, there is still a lack of clear understanding of how and why nonspecific adhesion may originate different resulting scenarios and how these interaction scenarios can be investigated. This work aims at bridging this gap by investigating the role of the interplay between cationic electrostatic and hydrophobic interactions in modulating the membrane stability during nonspecific adhesion phenomena. Here, the stability of the membrane has been studied employing anisotropic nanoprobes in zwitterionic lipid membranes with the support of coarse-grained molecular dynamics simulations to interpret the experimental observations. Lipid membrane electrical measurements and nanoscale visualization in combination with molecular dynamics simulations revealed the phenomena driving nonspecific adhesion. Any interaction with the lipidic bilayer is defect-mediated involving cationic electrostatically driven lipid extraction and hydrophobically-driven chain protrusion, whose interplay determines the existence of a thermodynamic optimum for the membrane structural integrity. These findings unlock unexplored routes to exploit nonspecific adhesion in lipid membranes. The proposed platform can act as a straightforward probing tool to locally investigate interactions between synthetic materials and lipid membranes for the design of antibacterials, antivirals, and scaffolds for tissue engineering.

The ability to program the behavior of magneto-reactive polymers requires the fine control of their magnetic microstructure during each step of the printing process. Here, a systematic study of magnetically driven self-assembly of Fe3O4 nanoparticles into chain-like structures is presented and used in a 3D printable formulation. The kinetics of chains formation, as well as their rotation, are studied by varying several experimental parameters: i.e. the viscosity of the formulation, the content of nanoparticles, the intensity of the applied magnetic field, and its application time. Experimental results are coupled to numerical simulations based on the dipolar approximation model, and the collected data are used to produce a dataset to precisely program the microstructure during the printing step. Thus, a desired microstructure in a 3D printed piece can be obtained by controlling the orientation and the length of the magnetic chains in each printed layer. This is achieved by modifying a commercial Digital Light Processing (DLP) 3D printer to apply magnetic fields of tunable intensity and direction. Finally, as a proof of concept, a pyramid-like structure was 3D printed, where each layer contains a specific and spatially oriented microstructure.

We present the shape transformation of a single layer of Au nanoparticles (NPs) when embedded in, and at the interface of, amorphous $\mathrm{Si}{\mathrm{N}}_{\mathrm{x}}$ and $\mathrm{Si}{\mathrm{O}}_{\mathrm{x}}$ ($\mathrm{a}\text{\ensuremath{-}}\mathrm{Si}{\mathrm{N}}_{\mathrm{x}}$ and $\mathrm{a}\text{\ensuremath{-}}\mathrm{Si}{\mathrm{O}}_{\mathrm{x}}$) thin films upon irradiation with 185-MeV Au ions to fluences ranging from 0.3 to $30\ifmmode\times\else\texttimes\fi{}{10}^{13}\phantom{\rule{0.16em}{0ex}}\mathrm{c}{\mathrm{m}}^{\ensuremath{-}2}$. Transmission electron microscopy (TEM) and high angular annular dark field microscopy were used to study the ion-shaping process. The former allows us to follow the overall change in geometry, size, and structure, while the latter reveals information about the relative position with respect to the interface. For Au NPs embedded in a single material, a lower elongation rate for $\mathrm{a}\text{\ensuremath{-}}\mathrm{Si}{\mathrm{N}}_{\mathrm{x}}$ was found in comparison to $\mathrm{a}\text{\ensuremath{-}}\mathrm{Si}{\mathrm{O}}_{\mathrm{x}}$. When at the interface of the two materials, TEM reveals a preferential elongation towards $\mathrm{a}\text{\ensuremath{-}}\mathrm{Si}{\mathrm{O}}_{\mathrm{x}}$. The latter demonstrates the use of $\mathrm{a}\text{\ensuremath{-}}\mathrm{Si}{\mathrm{N}}_{\mathrm{x}}$ for confining the ion-shaping process within an intermediate $\mathrm{a}\text{\ensuremath{-}}\mathrm{Si}{\mathrm{O}}_{\mathrm{x}}$ layer. The simulation of the temperature evolution during a single-ion impact was used to understand the difference in elongation rates between $\mathrm{a}\text{\ensuremath{-}}\mathrm{Si}{\mathrm{N}}_{\mathrm{x}}$ and $\mathrm{a}\text{\ensuremath{-}}\mathrm{Si}{\mathrm{O}}_{\mathrm{x}}$, as well as the asymmetric behavior when located at the interface using the three-dimensional inelastic thermal spike model with bulk thermophysical properties. The calculations show good agreement with the experimental observations and reveal a correlation between the thermal profile and the resulting NP geometry.

Elongated carbon structures, here denoted as carbon flakes (CF), are revealed after microwave-assisted hydrothermal carbonization of sodium lignosulfonate. The morphology of formed CF is investigated by transmission electron microscopy and atomic force microscopy. Interestingly, a wide range of length distributions (between 100 and 700 nm) and a relatively constant aspect ratio and thickness are observed, indicating structures clearly different from the carbon spheres commonly formed during hydrothermal carbonization of lignocellulosic biomass. Moreover, X-ray diffraction, Raman spectroscopy, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy provide further information of the chemical structure, which consist mainly of nanographitic domains with a high degree of defects such as oxygenated functional groups, hybridized sp3 carbon, and aliphatic side chains. Furthermore, new insights into the formation mechanisms are uncovered and the formation is speculated to proceed through the combined effect of microwave irradiation and a heterogeneous solid-solid conversion. The formed CF are anticipated as highly interesting products for a variety of material applications.

Nanocatalysts' degradation is a limiting factor for the development of polymer electrolyte membrane for fuel cells (PEMFCs). In this work, a dedicated sample holder has been used to mimic the cathode of a PEMFC at the earliest stages of the aging process, i.e., under accelerated stress test after up to 500 cycles. The mechanisms of surface area loss of supported platinum nanoparticles (Pt NPs) have been monitored in real-time and operando conditions by coupling liquid cell transmission electron microscopy (LTEM) to energy-filtered transmission electron microscopy (EFTEM), while cyclic voltammograms (CVs) were simultaneously recorded. The study has been performed using an ink made of a commercial catalyst (Tanaka-TEC10V50E) containing Pt NPs intended for automotive applications (3.0 +/- 0.4 nm). First, a protocol has been set up to mitigate the electron-beam-induced radiolysis effects to a level that related artifacts are hindered or at least not appreciably detected during the duration of the experiment. At the same time, the resolution limit of the microscope has been pushed below 1 nm. Afterward, several degradation pathways were first identified and categorized and then correlated to the evolution of both the electrochemical active surface area (ECSA) and the Pt oxide reduction peak. We analyze reported evidence that the electrochemical aging favors the dissolution of the smaller Pt NPs. Dissolved cations are then observed to redispose onto larger supported Pt particles (electrochemical Ostwald ripening) or to be transported within the electrolyte, being either the aqueous acidic solution or the ionomer where they can precipitate (dissolution/precipitation process).

We investigate, with a combination of ultrafast optical spectroscopy and semiclassical modeling, the photothermal properties of various water-soluble nanocrystal assemblies. Broadband pump-probe experiments with ∼100-fs time resolution in the visible and near infrared reveal a complex scenario for their transient optical response that is dictated by their hybrid composition at the nanoscale, comprising metallic (Au) or semiconducting ([Formula: see text]) nanostructures and a matrix of organic ligands. We track the whole chain of energy flow that starts from light absorption by the individual nanocrystals and subsequent excitation of out-of-equilibrium carriers followed by the electron-phonon equilibration, occurring in a few picoseconds, and then by the heat release to the matrix on the 100-ps timescale. Two-dimensional finite-element method electromagnetic simulations of the composite nanostructure and multitemperature modeling of the energy flow dynamics enable us to identify the key mechanism presiding over the light-heat conversion in these kinds of nanomaterials. We demonstrate that hybrid (organic-inorganic) nanocrystal assemblies can operate as efficient nanoheaters by exploiting the high absorption from the individual nanocrystals, enabled by the dilution of the inorganic phase that is followed by a relatively fast heating of the embedding organic matrix, occurring on the 100-ps timescale.

The elongation process under swift heavy ion irradiation (74 MeV Kr ions) of gold NPs, with a diameter in the range 10-30 nm, and embedded in a silica matrix has been investigated by combining experiment and simulation techniques: three-dimensional thermal spike (3DTS), molecular dynamics (MD) and a phenomenological simulation code specially developed for this study. 3DTS simulations evidence the formation of a track in the host matrix and the melting of the NP after the passage of the impinging ion. MD simulations demonstrate that melted NPs have enough time to expand after each ion impact. Our phenomenological simulation relies on the expansion of the melted NP, which flows in the track in silica with modified (lower) density, followed by its recrystallization upon cooling. Finally, the elongation of the spherical NP into a cylindrical one, with a length proportional to its initial size and a width close to the diameter of the track, is the result of the superposition of the independent effects of each expansion/recrystallization process occurring for each ion impact. In agreement with experiment, the simulation shows the gradual elongation of spherical NPs in the ion-beam direction until their widths saturate in the steady state and reach a value close to the track diameter. Moreover, the simulations indicate that the expansion of the gold NP is incomplete at each ion impact.

This article reports on the effect of silver nanoparticles (NPs), used as active fillers, on the piezoelectric response of polymer composites. In particular, it is demonstrated that the application of a periodic electric field drives a collective drift of surface atoms of the NPs along the field direction (“electrokinetic effect”) which, in turn, creates macroscopic reversible tensile states. Overdriving the system, in high‐field conditions, the electronic current is counterbalanced by a massive injection of Ag + ions into the matrix, producing a metastable exceptional expansion of the device. For similitude with the converse piezoelectric effect, it has been called the converse piezo–electro–kinetic effect. By using in situ spectroscopy, vibrometric analysis, real‐time UV‐visible spectroscopy, in situ electrical transmission electron microscopy, and in qualitative form ab initio and finite element method numerical simulations, i) the injection of ions from the NPs to the matrix, ii) the surface migration‐induced NP reshaping, and iii) the NP migration and consequent percolation path adjustments are shown. The implications of this study are significant for the development of ultrafast soft ionic actuators and create the premises for a broad range of applications in smart materials and devices.

Digital light processing is used for printing magnetoresponsive polymeric materials with tunable mechanical and magnetic properties. Mechanical properties are tailored, from stiff to soft, by combining urethane-acrylate resins with butyl acrylate as the reactive diluent. The magnetic response of the printed samples is tuned by changing the Fe3O4 nanoparticle loading up to 6 wt%. Following this strategy, magnetoresponsive active components are fabricated with programmable complex functions using external magnetic fields. Different objects are printed exhibiting varying stiffness and magnetic responses, probing different kinds of movements, such as rolling, translation, stretching, shape-shifting, and folding/unfolding.

Journal Article Ion Irradiation Shaping of Dense Two-dimensional Arrays of Au Nanoparticles Embedded in Silica Studied via TEM Get access P Mota-Santiago, P Mota-Santiago Department of Electronic Materials Engineering, Research School of Physics and Engineering, Australian National University, Canberra, Australia Search for other works by this author on: Oxford Academic Google Scholar F Kremer, F Kremer Centre for Advanced Microscopy, The Australian National University, Australia Search for other works by this author on: Oxford Academic Google Scholar G Rizza, G Rizza Ecole Polytechnique, Laboratoire des Solides Irradies (LSI) CEA/DSM/IRAMIS, CNRS 91128 Palaiseau Cedex, France Search for other works by this author on: Oxford Academic Google Scholar C Dufour, C Dufour CIMAP/CEA/CNRS/ENSICAEN/ Universite de Caen, 6 Boulevard du Marechal Juin, 1405 Caen Cedex 4, France Search for other works by this author on: Oxford Academic Google Scholar C Notthoff, C Notthoff Department of Electronic Materials Engineering, Research School of Physics and Engineering, Australian National University, Canberra, Australia Search for other works by this author on: Oxford Academic Google Scholar A Hadley, A Hadley Department of Electronic Materials Engineering, Research School of Physics and Engineering, Australian National University, Canberra, Australia Search for other works by this author on: Oxford Academic Google Scholar UH Hussain, UH Hussain Department of Electronic Materials Engineering, Research School of Physics and Engineering, Australian National University, Canberra, Australia Search for other works by this author on: Oxford Academic Google Scholar P Kluth P Kluth Department of Electronic Materials Engineering, Research School of Physics and Engineering, Australian National University, Canberra, Australia Search for other works by this author on: Oxford Academic Google Scholar Microscopy and Microanalysis, Volume 25, Issue S2, 1 August 2019, Pages 1610–1611, https://doi.org/10.1017/S143192761900878X Published: 01 August 2019