Active packaging is of great interest in the modern food industry due to increasing shelf life and enhancing food quality. The importance of this technology increases when natural polymers are used in the construction of active packages. Development of a natural, biodegradable, and dual-active film was aimed in this study. So, agar aerogel containing different amounts of chlorine-doped graphene quantum dots (Cl-GQDs) was prepared. Cl-GQDs had excitation-dependent fluorimetry behavior due to the zigzag edges of graphene. The mean diameter of spherical nanoparticles of Cl-GQDs was about 12 nm, according to HR-TEM images. The results of Raman and ATR-FTIR confirmed that chlorine was well-doped on the GQD structure. Cl-GQDs showed high UV-absorption capability and very strong antioxidant activity (94.31 %), which maintained these activities after incorporation into the agar aerogel. The doped chlorine was responsible for the capacity to charge transfer of GQDs. BET and SEM results showed that adding Cl-GQDs to agar caused a porous structure. Finally, different types of agar aerogels containing Cl-GQDs can be used considering the intended application of aerogel. Agar aerogel containing 20 % Cl-GQDs is suggested if a porous aerogel with good thermal insulation properties is considered. However, agar aerogel containing 1 % Cl-GQDs is suitable as an active film. In conclusion, while Cl-GQDs hold promise as sustainable and multifunctional food packaging materials, their potential toxic effects must be thoroughly evaluated. Future studies should explore migration, potential interactions with specific food matrices, and long-term safety to ensure consumer protection.

In recent years, polybenzoxazine aerogels have emerged as promising materials for various applications. However, their full potential has been hindered by the prevalent use of hazardous solvents during the preparation process, which poses significant environmental and safety concerns. In light of this, there is a pressing need to explore alternative methods that can mitigate these issues and propel the practical utilization of polybenzoxazine aerogels. To address this challenge, a novel approach involving the synthesis of heteroatom self-doped mesoporous carbon from polybenzoxazine has been devised. This process utilizes eugenol, stearyl amine, and formaldehyde to create the polybenzoxazine precursor, which is subsequently treated with ethanol as a safer solvent. Notably, the incorporation of boric acid in this method serves a dual purpose: it not only facilitates microstructural regulation but also reinforces the backbone strength of the material through the formation of intermolecular bridged structures between polybenzoxazine chains. Moreover, this approach allows ambient pressure drying, further enhancing its practicability and environmental friendliness. The resultant carbon materials, designated as ESC-N and ESC-G, exhibit distinct characteristics. ESC-N, derived from calcination, possesses a surface area of 289 m2 g-1, while ESC-G, derived from the aerogel, boasts a significantly higher surface area of 673 m2 g-1. Furthermore, ESC-G features a pore size distribution ranging from 5 to 25 nm, rendering it well suited for electrochemical applications such as supercapacitors. In terms of electrochemical performance, ESC-G demonstrates exceptional potential. With a specific capacitance of 151 F g-1 at a current density of 0.5 A g-1, it exhibits superior energy storage capabilities compared with ESC-N. Additionally, ESC-G displayed a more pronounced rectangular shape in its cyclic voltammogram at a low voltage scanning rate of 20 mV s-1, indicative of enhanced electrochemical reversibility. The impedance spectra of both carbon types corroborated these findings, further validating the superior performance of ESC-G. Furthermore, ESC-G exhibits excellent cycling stability, retaining its electrochemical properties even after 5000 continuous charge-discharge cycles. This robustness underscores its suitability for long-term applications in supercapacitors, reaffirming the viability of heteroatom-doped polybenzoxazine aerogels as a sustainable alternative to traditional carbon materials.

Intelligent and diversified development of modern detection technology greatly affects the battlefield survivability of military targets, especially infrared, acoustic wave, and radar detection expose targets by capturing their unavoidable infrared radiation, acoustic wave, and electromagnetic wave information, greatly affecting their battlefield survival and penetration capabilities. Therefore, there is an urgent need to develop stealth-protective materials that can suppress infrared radiation, reduce acoustic characteristics, and weaken electromagnetic signals. Fibrous three-dimensional porous materials, with their high porosity, excellent structural adjustability, and superior mechanical properties, possess strong potential for development in the field of stealth protection. This article introduced and reviewed the characteristics and development process of fibrous three-dimensional porous materials at both the micrometer and nanometer scales. Then, the process and characteristics of preparing fibrous three-dimensional porous materials through vacuum forming, gel solidification, freeze-casting, and impregnation stacking methods were analyzed and discussed. Meanwhile, their current application status in infrared, acoustic wave, and radar stealth fields was summarized and their existing problems and development trends in these areas from the perspectives of preparation processes and applicability were analyzed. Finally, several prospects for the current challenges faced by fibrous three-dimensional porous materials were proposed as follows: functionally modifying fibers to enhance their applicability through self-cross-linking; establishing theoretical models for the transmission of thermal energy, acoustic waves, and electromagnetic waves within fibrous porous materials; constructing fibrous porous materials resistant to impact, shear, and fracture to meet the needs of practical applications; developing multifunctional stealth fibrous porous materials to confer full-spectrum broadband stealth capability; and exploring the relationship between material size and mechanical properties as a basis for preparing large-scale samples that meet the application\'s requirement. This review is very timely and aims to focus researchers\' attention on the importance and research progress of fibrous porous materials in the field of stealth protection, so as to solve the problems and challenges of fibrous porous materials in the field of stealth protection and to promote the further innovation of fibrous porous materials in terms of structure and function.

Aromatic polyisocyanurate (PIR) aerogels are recognized as advanced porous materials and extensively studied due to their lightweight nature, high porosity, and specific surface area, which attribute to their outstanding thermal insulation properties. The inherent thermal stability of the PIR moieties, combined with great insulating performance, renders PIR aerogels highly suitable for building insulation applications. Nevertheless, materials containing isocyanurate obtained through direct trimerization of aromatic isocyanates exhibit brittleness, resulting in inferior mechanical performance. In order to enhance the processability of the PIR aerogels, we propose a cocyclotrimerization approach involving mixtures of mono- and difunctional aromatic isocyanates. This approach is designed to develop a PIR network with decreased cross-linking density and brittleness. Herein, we developed an array of PIR aerogels from different alkyl chain-modified isocyanate mixtures. The resulting PIR aerogels exhibited high porosity (>89%), a large surface area (∼300 m2/g), superinsulating performance with ultralow thermal conductivity (∼16.8 mW m-1 K-1), notable thermal stability (Td5% ∼ 250 °C), improved mechanical performance, and intrinsic hydrophobicity without the need for postmodification. These high-performance organic aerogels hold significant promise for applications requiring superinsulating materials.

Laser-induced projectile impact testing (LIPIT) based on synchrotron imaging is proposed and validated. This emerging high-velocity, high-strain microscale dynamic loading technique offers a unique perspective on the strain and energy dissipation behavior of materials subjected to high-speed microscale single-particle impacts. When combined with synchrotron radiation imaging techniques, LIPIT allows for in situ observation of particle infiltration. Two validation experiments were carried out, demonstrating the potential of LIPIT in the roentgenoscopy of the dynamic properties of various materials. With a spatial resolution of 10 µm and a temporal resolution of 33.4 µs, the system was successfully realized at the Beijing Synchrotron Radiation Facility 3W1 beamline. This innovative approach opens up new avenues for studying the dynamic properties of materials in situ.

Polypropylene-based aerogels with high surface area have been developed for the first time. By chemical crosslinking of polypropylene with oligomeric capped-end amino compounds, followed by dissolution, thermally induced phase separation, and the supercritical CO2 drying process or freeze-drying method, the aerogels exhibit high specific surface areas up to 200 m2/g. Moreover, the silica-cage multi-amino compound was utilized in a similar vein for forming hybrid polypropylene aerogels. According to the SEM, the developed polypropylene-based aerogels exhibit highly porous morphology with micro-nanoscale structural features that can be controlled by processing conditions. Our simple and inexpensive synthetic strategy results in a low-cost, chemically resistant, and highly porous material that can be tailored according to end-use applications.

The use of solar interface evaporation for seawater desalination or sewage treatment is an environmentally friendly and sustainable approach; however, achieving efficient solar energy utilization and ensuring the long-term stability of the evaporation devices are two major challenges for practical application. To address these issues, we developed a novel ceramic fiber@bioderived carbon composite aerogel with a continuous through-hole structure via electrospinning and freeze-casting methods. Specifically, an aerogel was prepared by incorporating perovskite oxide (Ca0.25La0.5Dy0.25)CrO3 ceramic fibers (CCFs) and amylopectin-derived carbon (ADC). The CCFs exhibited remarkable photothermal conversion efficiencies, and the ADC served as a connecting agent and imparted hydrophilicity to the aerogel due to its abundant oxygen-containing functional groups. After optimizing the composition and microstructure, the (Ca0.25La0.5Dy0.25)CrO3 ceramic fiber@biomass-derived carbon aerogel demonstrated remarkable properties, including efficient light absorption and rapid transport of water and solutes. Under 1 kW m-2 light intensity irradiation, this novel material exhibited a high temperature (48.3 °C), high evaporation rate (1.68 kg m-2 h-1), and impressive solar vapor conversion efficiency (91.6%). Moreover, it exhibited long-term stability in water evaporation even with highly concentrated salt solutions (25 wt%). Therefore, the (Ca0.25La0.5Dy0.25)CrO3 ceramic fiber@biomass-derived carbon aerogel holds great promise for various applications of solar interface evaporation.

The potential of aerogels as catalysts for the synthesis of a relevant class of bis-heterocyclic compounds such as bis(indolyl)methanes was investigated. In particular, the studied catalyst was a nanocomposite aerogel based on nanocrystalline nickel ferrite (NiFe2O4) dispersed on amorphous porous silica aerogel obtained by two-step sol-gel synthesis followed by gel drying under supercritical conditions and calcination treatments. It was found that the NiFe2O4/SiO2 aerogel is an active catalyst for the selected reaction, enabling high conversions at room temperature, and it proved to be active for three repeated runs. The catalytic activity can be ascribed to both the textural and acidic features of the silica matrix and of the nanocrystalline ferrite. In addition, ferrite nanocrystals provide functionality for magnetic recovery of the catalyst from the crude mixture, enabling time-effective separation from the reaction environment. Evidence of the retention of species involved in the reaction into the catalyst is also pointed out, likely due to the porosity of the aerogel together with the affinity of some species towards the silica matrix. Our work contributes to the study of aerogels as catalysts for organic reactions by demonstrating their potential as well as limitations for the room-temperature synthesis of bis(indolyl)methanes.

The transition from fossil fuels is in part limited by our inability to store energy at different scales. Batteries are therefore in high demand, and we need them to store more energy, be more reliable, durable and have less social and environmental impact. Silica-poly(vinyl alcohol) (PVA) composite aerogels doped with sodium perchlorate were synthesized as novel electrolytes for potential application in solid-state sodium batteries. The aerogels, synthesized by one-pot synthesis, are light (up to 214 kg m-3), porous (~85%), exhibit reduced shrinkage on drying (up to 12%) and a typical silica aerogel microstructure. The formation of a silica network and the presence of PVA and sodium perchlorate in the composite were confirmed by FTIR and TGA. The XRD analysis also shows that a predominantly amorphous structure is obtained, as crystalline phases of polymer and salt are present in a very reduced amount. The effects of increasing polymer and sodium salt concentrations on the ionic conductivity, assessed via electrochemical impedance spectroscopy, were studied. At a PVA concentration of 15% (w/w silica precursors), the sodium conduction improved significantly up to (1.1 ± 0.3) × 10-5 S cm-1. Thus, this novel material has promising properties for the envisaged application.

Various graphene derivatives have been known as electrode-active materials for fabricating supercapacitors. Interconnected graphene networks with adjustable porous structures, i.e., 3D graphene aerogels (GAs), can control the restacking of graphene sheets very well and, thus, lead to the enhanced performance supercapacitors. In this study, carbohydrates (sucrose and fructose) were used to make two types of 3D porous carbohydrates-graphene aerogels, sucrose-graphene aerogel (SCR) and fructose-graphene aerogel (FRC). Carbohydrates operate as a cross-linking and reductant agent. Voltammograms of supercapacitor electrodes based on the FRC and SCR indicate a more rectangular shape with a larger area and a superior current than the GA (graphene aerogel without using carbohydrates) electrode. They have better capacitive performance, more electron transportation ability, and higher specific capacitance (CS) values than GA. The supercapacitor electrodes based on FRC, SCR, and GA demonstrate the CS values of 257.2 F g -1, 221.0 F g -1, and 95 F g -1 at ѵ = 10 mV.s-1, respectively. Improvement in the performance of SCR and FRC supercapacitor electrodes, in comparison to GA, is attributed to the porous interconnected feature of their structures and their suitable available surface area, which facilitates electron and ion transportation throughout graphene networks. These supercapacitors also show excellent stability after recording 5000 consecutive voltammograms.