Search Results (1,940)

Additive-free methylammonium lead bromide (MAPbBr₃) electrodes were fabricated by electrophoretic deposition (EPD) directly on Cu foil to investigate Li-storage kinetics while minimizing electrochemical and interfacial contributions associated with polymer binders and conductive carbon additives. The EPD-derived film formed a porous particulate coating and exhibited an optical band gap of approximately 2.24 eV, confirming the retention of MAPbBr₃ after deposition. Peak-resolved electrochemical analysis showed that Li storage does not proceed through a single intercalation pathway. The low-voltage cathodic peak showed mixed diffusion/interfacial behavior. In contrast, other redox peaks were mainly diffusion-controlled, with b-values close to 0.5. After cycling, energy dispersive spectroscopy revealed decreased N, Br, and Pb contents and increased F, P, and O signals, indicating MAPbBr₃ reconstruction and electrolyte-derived interphase formation. Electrochemical impedance spectroscopy results showed that charge-transfer resistance decreased during discharge, suggesting kinetic activation of the reconstructed interface. This work establishes additive-free EPD as a powerful platform for revealing cycling-induced interfacial reconstruction and multistep Li-storage kinetics in MAPbBr₃ perovskite electrodes. Full article

Shape memory polymers (SMPs) have emerged as a distinctive class of functional polymers for tissue engineering and regenerative medical devices because they couple programmable shape transformation with the biological, mechanical, and degradation requirements of regenerating tissue. Unlike conventional static scaffolds, SMP-based constructs can be delivered in compact temporary configurations, deployed under clinically relevant stimuli, and recovered into porous, anatomically conformal architectures that mechanically and biologically engage with host tissue. This review provides an engineering-oriented perspective on SMPs as functional polymers, emphasizing how shape recovery alone is insufficient and how regenerative performance emerges from coupled control of polymer chemistry, transition behavior, recovery force, fixity, degradation kinetics, and cytocompatibility. Material platforms ranging from biodegradable polyesters and polyurethanes to hydrogels, natural-polymer composites, and dynamic covalent networks are compared in terms of their ability to support tissue-specific functions including minimally invasive deployment, self-fitting, mechanical conditioning, and staged remodeling. The review further discusses 4D-printed patient-specific architectures and translational barriers, including sterilization, packaging, fatigue, manufacturing reproducibility, and regulatory validation. Together, these perspectives reframe SMPs from shape-recovery materials into integrated regenerative engineering platforms guiding the next generation of dynamic polymeric biomaterials. Full article

Silica aerogels are among the most extraordinary porous materials produced through sol–gel chemistry, distinguished by ultralow density, exceptionally high porosity, large specific surface area, and extremely low thermal conductivity. Despite these characteristics, widespread application of conventional silica aerogels has been constrained by inherent brittleness, poor mechanical strength, and moisture sensitivity. Significant research has therefore focused on silica aerogel composites, in which reinforcing or functional phases—fibers, polymers, carbon nanomaterials, metal oxides, and biopolymers—are integrated into the silica network to enhance mechanical robustness, flexibility, hydrothermal stability, electrical conductivity, catalytic activity, and multifunctionality while largely preserving the parent aerogel’s desirable properties. We review the synthesis, characterization, properties, and applications of silica aerogel composites. Sol–gel processing and drying technologies are discussed, followed by composite-formation strategies and the advanced techniques used to evaluate structural, mechanical, thermal, surface, and functional properties. The effects of reinforcing phases on mechanical performance, thermal conductivity, and hydrothermal stability are analyzed, and current and emerging applications in thermal insulation, environmental remediation, catalysis, acoustic damping, aerospace systems, biomedical engineering, and energy storage are highlighted. Finally, key challenges and future directions involving multifunctional materials, green synthesis, and data-driven materials design are discussed. Full article

Composite micromechanics is commonly divided between rapid mean-field estimates and computationally intensive full-field representative-volume-element (RVE) simulations. When these routes use different files, conventions and post-processing procedures, discrepancies can reflect bookkeeping rather than mechanics. This paper introduces HARVEST (Homogenisation and Representative Volume Element Simulation Tool; version 0.7.0.dev0), a general-purpose platform that coordinates mean-field homogenisation, three-dimensional RVE generation, finite-element model preparation, solver execution, homogenisation, parameter studies and post-processing through common project, service and provenance boundaries. The numerical framework is material-agnostic, whereas verification and validation are demonstrated using polymer-based nanocomposites. The Mori–Tanaka bulk response for spherical inclusions reproduces the Hashin composite-sphere result to machine precision, independent orientation procedures agree to a relative difference of $1.6\times {10}^{-14}$, and a sequential coated-particle approximation differs from an analytical composite-sphere reference by at most $0.417$% over 24 polymer-relevant configurations. An archived full-field epoxy/silica-type campaign using kinematic uniform boundary conditions and ${20}^3$ structured cells remains within the Hashin–Shtrikman interval at five inclusion fractions, with realisation scatter below $0.4$%. For published epoxy nanocomposites, aligned halloysite-nanotube predictions differ from measured flexural moduli by $-0.89$ and $+0.48$%, while spherical carboxyl-terminated butadiene–acrylonitrile-rubber predictions differ by $-7.03$ and $-2.25$%. The main conclusion is that a shared, traceable description of constituents, morphology, loading and outputs supports rapid mean-field screening followed by selective full-field analysis using the same material definition. The principal advantage over single-route or loosely coupled workflows is cross-route consistency and reproducibility. HARVEST is applicable to formulation screening, sensitivity studies and local-field assessment in particulate, tubular, rubber-modified, porous and mixed-matrix polymer systems, and can be extended through validated constitutive, geometry, solver and result adapters. Full article

In this study, we present the development of selective-area porous GaN (SPG) microarrays integrated with embedded quantum dots (QDs) for next-generation display applications. We report a dielectric hard mask-based architecture that withstands high etching voltages without suffering structural damage, overcoming the limitations of conventional polymer masks. This process provides precise control over both vertical and lateral pore propagation, achieving an effective pixel size of 15 μm and realizing an ultrahigh-resolution (>1270 ppi) display structure. Furthermore, optical performance measurements confirmed that the obtained array exhibited an excellent color gamut, reaching 119.2% of the NTSC and 95.6% of the Rec. 2020 standards. Therefore, the present dielectric hard mask-based patterning technology provides an effective solution for achieving both process stability and high-resolution pixel structures, enabling the fabrication of high-performance micro-LED displays with full-color capabilities. Full article

Radiation techniques represent an innovative and alternative method for polymer gelation or crosslinking; their application in aerogel research has not been extensively investigated. The irradiation of polymer solutions, either with or without a crosslinking agent, may result in stable polymer gels with a highly developed mesoporous structure. In this study, the effect of the pectin polysaccharide concentration, the presence of PVA, and the dose of ionizing radiation (27–58 kGy) were systematically investigated, particularly with respect to the structural, textural, and mechanical properties. The pectin/PVA and PVA were crosslinked in aqueous solution via ionizing radiation using an electron beam. The results demonstrated that the radiation crosslinking of a hydrophilic synthetic polymer in the presence of natural polysaccharides, such as pectin, is an effective strategy for engineering porous materials with a controlled structure, namely aerogels, of good stability, and favorable functional properties. The resulting composite aerogels were characterized by a BET-determined specific surface area of 200–241 m²/g and an estimated porosity of over 91%, compared with values of 28–46 m²/g, 0.22 g/cm³ and approximately 81.5% for aerogels produced using the freeze–thaw method. Full article

Polymer aerogels have attracted increasing attention as lightweight porous materials for thermal insulation, separation, adsorption, remediation, and other environmental applications. Their low density and tunable surface chemistry also make them suitable for converting renewable, recycled, and waste-derived feedstocks into value-added materials. However, their overall sustainability remains difficult to assess because most studies focus on material properties, whereas solvent use, drying energy, processing yield, durability, regeneration, and end-of-life pathways are reported less consistently. This review examines sustainable polymer aerogels from the perspectives of cleaner production and waste valorization and focuses on two main features. First, a unified multiscale framework of structure, formation, and performance links network formation mechanisms, pore architecture, and macroscopic behavior across biomass-derived, thermoset, dynamic covalent, hybrid, and recycled polymer aerogels, which are compared in terms of feedstock origin, processing intensity, functional performance, durability, and circularity. Second, structure–property mapping is combined with sustainability-constrained, AI-guided design, with environmental descriptors treated as optimization objectives from the outset rather than as post hoc justifications. Particular attention is given to waste and secondary resources, including agricultural residues, textile waste, paper waste, recycled poly(ethylene terephthalate), and end-of-life tire fibers. The review also discusses how life-cycle assessment, service-based functional units, and minimum reporting standards can help assess whether sustainability claims are supported by measurable environmental benefits. Several recurring limitations emerge from the literature: sustainability is often discussed only qualitatively, processing data are insufficient to support robust life-cycle assessments, solvent exchange and drying remain major environmental hotspots, and circularity claims frequently conflate bio-based content, biodegradability, recyclability, and reusability. Finally, the review discusses how data-driven tools, including literature mining, machine learning, and multi-objective optimization, can support polymer-aerogel design when environmental descriptors are included from the beginning of materials development. The review also proposes a reporting and design roadmap for future work toward polymer aerogels that combine useful performance with lower resource intensity and credible end-of-life value retention. Full article

Zeolitic imidazolate framework-8 (ZIF-8) has emerged as a material for electrochemical energy conversion, serving dual primary roles in fuel cell technologies: (i) as an electrocatalyst precursor for oxygen reduction reaction (ORR) and methanol oxidation reaction (MOR) through pyrolysis-derived N-doped porous carbons and metal–nitrogen–carbon (M–N–C) structures, and (ii) as a membrane component that enhances proton conductivity via imidazole-mediated Grotthuss hopping while suppressing fuel crossover through molecular sieving. This comprehensive review systematically evaluates ZIF-8 performance across multiple fuel cell types, including primarily proton exchange membrane fuel cells (PEMFCs), as well as direct methanol fuel cells (DMFCs), anion exchange membrane fuel cells (AEMFCs), and microbial fuel cells (MFCs), while also covering related electrochemical applications such as zinc–air batteries, supercapacitors, and water splitting devices, where ZIF-8-derived materials demonstrate improved catalytic activity. The review examines structure–performance relationships, highlighting strategies such as heteroatom doping, bimetallic synergy, hierarchical porosity engineering, and polymer composite fabrication that have enabled ZIF-8-based catalysts to achieve ORR half-wave potentials and PEMFC power densities, rivaling commercial Pt/C systems. ZIF-8 composite membranes demonstrate proton conductivities in polybenzimidazole systems and effective methanol blocking. Despite improved progress, challenges persist regarding long-term stability, scalable synthesis, and degradation mechanism understanding. This review critically analyzes recent advances, identifies performance-limiting factors across applications, and outlines future research directions for developing commercially viable ZIF-8-based electrochemical technologies. Full article

To address the susceptibility of polymer gels to syneresis and failure under high-temperature, high-salinity (HTHS) reservoir conditions, a zwitterionic terpolymer was synthesized from acrylamide (AM), 2-acrylamido-2-methylpropanesulfonic acid (AMPS), and dimethyldiallylammonium chloride (DMDAAC), and subsequently crosslinked with a phenolic system to produce an intramolecular salt-structured polymer gel with exceptional thermal and saline tolerance. Through systematic formulation optimization, the optimal composition was established as 0.3 wt% zwitterionic polymer, 0.03 wt% resorcinol, 0.3 wt% hexamethylenetetramine, and 0.1 wt% thiourea. X-ray photoelectron spectroscopy and zeta potential measurements confirmed that quaternary ammonium cations and sulfonate anions on the polymer chains associate via electrostatic attraction to form intramolecular salt bridges, which induce an anti-polyelectrolyte effect and thereby confer superior salt tolerance and thermal stability. Following aging for 140 days at 115 °C in formation water, the gel exhibited a syneresis rate below 30%, demonstrating favorable long-term stability under the tested high-temperature and high-salinity conditions. Thermogravimetric analysis and differential scanning calorimetry further characterized the thermal-transition behavior of the gel under programmed heating conditions. Scanning electron microscopy revealed a homogeneous honeycomb-like porous crosslinked network. Rheological testing demonstrated a storage modulus (G′) of 1.115 Pa and a loss modulus (G″) of 0.205 Pa, indicating an elasticity-dominated viscoelastic response and strong resistance to shear deformation. Single-core plugging experiments showed that at an injection volume of 0.2 PV, the gel achieved a plugging efficiency of 85.15% and a breakthrough pressure gradient of 18.6 MPa/m, with significant secondary plugging capability. In a heterogeneous dual-core model with a permeability contrast of approximately 10, the diversion rate into the low-permeability layer increased to 73.6%, effectively improving the water injection profile. This intramolecular salt-structured molecular design demonstrates potential for deep-profile control under high-temperature and high-salinity reservoir conditions. Full article

The development of straightforward and efficient strategies for the preparation of polymer-functionalized mesoporous silica remains an important challenge in the design of advanced hybrid materials. Herein, we report a novel and simplified approach to the covalent functionalization of mesoporous silica particles (MSP) with poly(2-ethyl-2-oxazoline) (PEtOx), based on the direct termination of living cationic polymer chains by amino groups immobilized on the silica surface. In contrast to conventional grafting-to methods, the proposed strategy eliminates the need for polymer end-group functionalization while avoiding the synthetic complexity associated with surface-initiated polymerization. Well-defined PEtOx chains with number-average molar masses of 5000 and 7500 g mol⁻¹ were synthesized by cationic ring-opening polymerization (CROP) and subsequently grafted onto amino-functionalized MSP. Successful covalent immobilization of the polymer was confirmed by Fourier-transform infrared spectroscopy (FT-IR), elemental analysis, thermogravimetric analysis (TGA), scanning electron microscopy (SEM), transmission electron microscopy (TEM), contact angle measurements, and nitrogen adsorption–desorption studies. The modification preserved the ordered mesoporous architecture while increasing particle hydrophilicity and decreasing the specific surface area and pore volume due to polymer incorporation. Shorter polymer chains exhibited higher grafting efficiency than higher-molar-mass analog, indicating that steric hindrance is an important factor influencing the grafting process. The presented methodology provides a versatile and experimentally accessible platform for the preparation of well-defined poly(2-oxazoline)-functionalized mesoporous silica with tunable physicochemical properties. Owing to the combination of a porous inorganic framework and a polymer shell, the obtained hybrid materials represent promising candidates for drug delivery, adsorption technologies, and other advanced biomedical and environmental applications. Full article

As cutting-edge semiconductor devices become smaller and more densely packed (i.e., ultra large-scale integration, ULSI), there is an increased risk of parasitic capacitance preventing proper device operation. There is consequently growing interest in the development of low-permittivity dielectric materials to serve as intermetal/interlayer coatings that would minimize this effect. Highly porous aerogels exhibit extremely low dielectric permittivity; silica-based aerogel films, in particular, are candidates for this application. The present report focuses on the synthesis, structure and dielectric permittivity of hydrophobic, tetramethyl orthosilicate (TMOS)-based silica aerogels prepared in disc-form. Using our 3D printed polymer sample holder with few metallic components, we are now able to determine the dielectric permittivity of highly porous, hydrophobic silica aerogels in the very low frequency (VLF) range, 10–27 kHz. Commercial systems that operate in the VLF range include circuits for biological signal processing, characterized by low amplitude and frequency, and circuits that operate in marine environments, where the useful frequency range is limited by acoustic signal deterioration. During impedance measurements, aerogel samples were confined in pure, dry oxygen atmosphere. Low mass density (10–250 mg/cm³) TMOS-based aerogel discs present structural characteristics and relative dielectric permittivity values in the VLF range that are not readily comparable with analogous data reported to date in the relevant literature. Full article

Porous polymer nanocomposites incorporating metal oxide nanoparticles (SiO₂, ZrO₂, and TiO₂) were synthesized via the aza–Michael addition reaction of ethyleneamines with poly(ethylene glycol) diacrylate (PEGDA) under polymerization-induced phase-separation conditions. The resulting nanocomposites exhibited interconnected particulate morphologies with particle diameters ranging from less than 0.5 to 5.0 μm. Increasing the nanoparticle content led to a significant reduction in particle size, indicating that the nanoparticles influenced the phase-separation process and the development of the porous structure. Energy-dispersive X-ray spectroscopy confirmed the homogeneous distribution of nanoparticles throughout the polymer matrix. The refinement of the porous morphology increased the bulk density and consequently enhanced the Young’s modulus of the nanocomposites. In addition, porous nanocomposites containing SiO₂ nanoparticles exhibited distinct coloration when immersed in toluene owing to the Christiansen filter effect. The transmission wavelength shifted toward longer wavelengths with increasing SiO₂ content, which was attributed to a decrease in the effective refractive index of the porous nanocomposites. These results demonstrate that the incorporation of metal oxide nanoparticles provides an effective strategy for controlling the morphology, mechanical properties, and optical functionality of porous polymer nanocomposites. Full article

Catalytic transformation of carbon dioxide (CO₂) into high-value-added chemicals represents a promising approach for CO₂ emission reduction and utilization. Herein, single-atom ruthenium (Ru) supported on N-heterocyclic carbene (NHC)-functionalized hypercrosslinked polymers were fabricated and applied as recyclable catalysts for the N-formylation of amines using CO₂ and H₂ as feedstocks. Catalytic evaluations demonstrated that the chemical structure of the NHC ligand had a significant influence on catalytic activity. Specifically, P(PhPy-TPB)-Ru, functionalized with a single pyridine moiety on the NHC ligand, exhibited the optimal catalytic performance, even slightly outperforming its homogeneous counterpart. Furthermore, mechanistic studies indicated that both the base and solvent played pivotal roles in modulating the reaction activity. In particular, the use of methanol as the solvent in the presence of a base significantly enhanced reaction efficiency, which was attributed to the in situ generation of methyl formate as a key intermediate. Notably, the developed catalytic system possessed excellent catalytic efficiency, a broad substrate scope, superior stability, and easy recyclability, allowing the catalyst to be reused for up to eight consecutive cycles without significant loss of catalytic activity. Full article

Passive daytime radiative cooling (PDRC) technology with high solar reflectance and high infrared emissivity has been increasingly applied in green buildings. However, current PDRC designs are either high-cost or require additional multi-step fabrication processes, and both factors hinder their broader industrial application. Here, we present a low-cost, easy-to-process, scalable and uncomplicated porous epoxy-based radiative cooling coating via a simple Pickering high-internal-phase-emulsion (HIPE) approach. The obtained porous epoxy-based coating has micro- and submicropores. These hierarchical porous microstructures enable a synergistic interaction between the filler and the porous microstructure, thus enhancing the radiative cooling performance. As a result, the obtained porous epoxy-base polymer with alumina as fillers (PEP-A) coating presents a high solar reflectance of 95.6% in the wavelength range of 0.3–2.5 μm and a high infrared emissivity of 96.3% in the wavelength range of 8–14 μm, as well as a maximum subambient cooling temperature of 3.4 °C and an average cooling power of 105.6 W·m⁻² under solar shortwave radiation of 123.01–134.67 W·m⁻². Furthermore, the PEP-A coating can be easily applied via roll-coating, blade-coating, or brush-coating, and self-cures on diverse substrates like aluminum sheets, steel plates, polypropylene sheets, bricks, and wall surfaces without any additional template-extraction process. In particular, the cost of the raw materials for the PEP-A coating is 0.2–1.3% of that of previously reported radiative cooling coatings (e.g., Poly(vinylidenefluoride-co-hexafluoropropylene) and polydimethylsiloxane). The extraction-free nature, easy processability, self-curing ability, and low cost of the PEP-A coating make it very promising for large-scale PDRC production and applications. Full article

Background/Objectives: Shape-memory biodegradable scaffolds (4D scaffolds) represent promising platforms for minimally invasive tissue engineering and localized drug delivery. This study investigated how two different fabrication techniques, electrospinning (ES) and extrusion-based direct ink writing (DIW), influence the structural, thermal, mechanical, shape-memory, and drug-release properties of poly(L-lactide-co-caprolactone) (PLA/PCL 70:30) scaffolds loaded with dexamethasone (DXM). Methods: DXM-loaded PLA/PCL 70:30 scaffolds were fabricated by ES and DIW. The resulting matrices were characterized in terms of morphology, mass, thickness, drug-loading efficiency, thermal properties by differential scanning calorimetry, shape-memory performance, tensile mechanical properties, and in vitro DXM release. Results: Both fabrication techniques produced DXM-loaded matrices with comparable mass and thickness and high loading efficiencies (>82%). Glass transition temperatures ranged between 33 and 39 °C, supporting thermally induced shape recovery under physiologically relevant conditions, while ES processing was associated with higher polymer crystallinity. All scaffolds exhibited shape-memory behavior, with recovery ratios exceeding 90%. ES scaffolds displayed a microporous nanofibrous architecture, whereas DIW scaffolds showed a more open and highly porous structure. These morphological differences were reflected in their mechanical behavior: ES scaffolds exhibited higher tensile strength (up to 16.5 MPa vs. 1.9 MPa) and elongation at break (up to 320% vs. 243%). Drug-release profiles were also fabrication-dependent, with ES scaffolds reaching a plateau at approximately 80% DXM release, whereas DIW scaffolds showed near-complete release within 48 h. Conclusions: Both fabrication approaches preserved the thermoresponsive shape-memory behavior of PLA/PCL 70:30 but generated distinct scaffold architectures that strongly influenced mechanical performance and DXM-release kinetics. Full article