Applications Of Aerogels Research Articles

Electrothermal Transformations within Graphene-Based Aerogels through High-Temperature Flash Joule Heating.

Flash Joule heating of highly porous graphene oxide (GO) aerogel monoliths to ultrahigh temperatures is exploited as a low carbon footprint technology to engineer functional aerogel materials. Aerogel Joule heating to up to 3000 K is demonstrated for the first time, with fast heating kinetics (∼300 K·min-1), enabling rapid and energy-efficient flash heating treatments. The wide applicability of ultrahigh-temperature flash Joule heating is exploited in a range of material fabrication challenges. Ultrahigh-temperature Joule heating is used for rapid graphitic annealing of hydrothermal GO aerogels at fast time scales (30-300 s) and substantially reduced energy costs. Flash aerogel heating to ultrahigh temperatures is exploited for the in situ synthesis of ultrafine nanoparticles (Pt, Cu, and MoO2) embedded within the hybrid aerogel structure. The shockwave heating approach enables high through-volume uniformity of the formed nanoparticles, while nanoparticle size can be readily tuned through controlling Joule-heating durations between 1 and 10 s. As such, the ultrahigh-temperature Joule-heating approach introduced here has important implications for a wide variety of applications for graphene-based aerogels, including 3D thermoelectric materials, extreme temperature sensors, and aerogel catalysts in flow (electro)chemistry.

Hybrid Materials of Bio-Based Aerogels for Sustainable Packaging Solutions.

This review explores the field of hybrid materials in the context of bio-based aerogels for the development of sustainable packaging solutions. Increasing global concern over environmental degradation and the growing demand for environmentally friendly alternatives to conventional packaging materials have led to a growing interest in the synthesis and application of bio-based aerogels. These aerogels, which are derived from renewable resources such as biopolymers and biomass, have unique properties such as a lightweight structure, excellent thermal insulation, and biodegradability. The manuscript addresses the innovative integration of bio-based aerogels with various other materials such as nanoparticles, polymers, and additives to improve their mechanical, barrier, and functional properties for packaging applications. It critically analyzes recent advances in hybridization strategies and highlights their impact on the overall performance and sustainability of packaging materials. In addition, the article identifies the key challenges and future prospects associated with the development and commercialization of hybrid bio-based aerogel packaging materials. The synthesis of this knowledge is intended to contribute to ongoing efforts to create environmentally friendly alternatives that address the current problems associated with conventional packaging while promoting a deeper understanding of the potential of hybrid materials for sustainable packaging solutions.

Regulating microstructures of aerogels by controlling phase separation mechanism for improving specific surface area and energy harvesting

Aerogels with 3D porous structures have been attracting increasing attention among functional materials due to their advantages of being lightweight and high specific surface area. Precise control of the porous structure of aerogel is essential to improve its performance. In this work, polylactic acid (PLA) aerogels with distinctly different microstructures were fabricated by precisely controlling the phase separation behavior of the ternary solution system. Rheological and theoretical analyses have revealed that the interactions between polymer molecules, solvents and non-solvents play a crucial role in determining the nucleation and growth of poor olymer and rich polymer phases. By adjusting the non-solvent type and the solution composition, aerogels with spider network structure, bead-like connected microsphere structure, and cluster petal structure were obtained. Ideal spinodal phase separation conditions were obtained to produce aerogels with a homogeneous fiber network structure. The optimum PLA aerogel achieved an extremely porosity of 96 % and a high specific surface area of 114 m2/g, which rendered it with excellent triboelectric generation performance. Thus, this work provides fundamental insights into the precise regulation of the phase separation behavior and the structure of the aerogel, which can help boost the performance and expand the applications of PLA aerogels.

Exoskeleton-like mechanical enhanced low-density aerogel with electromagnetic interface shielding and infrared stealth

The integrated design and mechanical enhancement of multifunctional electromagnetic interference shielding and infrared stealth aerogels are challenging for the development and application of novel aerogels. Here, inspired by the biological exoskeleton to enhance the body, we develop the exoskeleton-like aramid nanofiber/polyimide/MXene (APM) aerogel through a secondary impregnation strategy. For APM aerogel, the polyimide reinforcement layer makes the aerogel more elastic and tough; the Ti3C2Tx-MXene exoskeleton enhances the strength and stiffness of the aerogel. Importantly, Ti3C2Tx-MXene forms a continuous conductive network on the surface of the airgel backbone, resulting in high-performance electromagnetic interference (EMI) shielding (EMI shielding efficiency reached 55.315 dB at an ultra-low Ti3C2Tx content of 0.58 vol%), high-efficiency infrared radiation (IR) stealth (ultra-low thermal conductivity of 0.0666 W·m−1·K−1 and IR emissivity of 0.566 at 3–5 μm and 0.55 at 8–14 μm). This study provides a way to design robust aerogel materials with infrared stealth and electromagnetic shielding compatibility.

Deep integration of pyrolysis kinetics and pyrolysis mechanism of polyimide aerogels

As novel advanced organic materials, polyimide aerogels (PI-AER) exhibit high porosity and excellent thermal stability. For the general and safe application of PI-AER, it is imperative to clarify their thermal decomposition process. The kinetic parameters of PI-ARE pyrolysis were calculated using different traditional kinetic methods, and the results showed that the PI-AER pyrolysis process conformed to the Fn-like mechanistic function model with an average activation energy of 143.984 kJ/mol. The pyrolysis mechanism function model of the main pyrolysis stages was optimized and reconstructed to obtain the optimal solution f(α). In addition, the concentration changes of pyrolysis products with increasing temperature were monitored by TG-MS and the PI-AER bond breaking mechanism was analyzed. Finally, the TG curves were fitted piecewise to obtain Ea and lnA for the two pyrolysis processes. Combined with the pyrolysis mechanism and two-stage kinetic parameter analysis, the effects of the two pyrolysis stages of PI-AER on the kinetic parameters were elucidated. It was shown that the activation energies of solvent volatilization and desorption and PI-AER main chain were 60.1 kJ/mol and 147.76 kJ/mol, respectively. This study provides fundamental industrial parameters for the application of polyimide aerogels in extreme conditions.

Aerogels as Carriers for Oral Administration of Drugs: An Approach towards Colonic Delivery.

Polysaccharide aerogels have emerged as a highly promising technology in the field of oral drug delivery. These nanoporous, ultralight materials, derived from natural polysaccharides such as cellulose, starch, or chitin, have significant potential in colonic drug delivery due to their unique properties. The particular degradability of polysaccharide-based materials by the colonic microbiota makes them attractive to produce systems to load, protect, and release drugs in a controlled manner, with the capability to precisely target the colon. This would allow the local treatment of gastrointestinal pathologies such as colon cancer or inflammatory bowel diseases. Despite their great potential, these applications of polysaccharide aerogels have not been widely explored. This review aims to consolidate the available knowledge on the use of polysaccharides for oral drug delivery and their performance, the production methods for polysaccharide-based aerogels, the drug loading possibilities, and the capacity of these nanostructured systems to target colonic regions.

Compendium of Safety Regulatory for Safe Applications of Aerogels.

An increasing number of aerogels as nanostructured highly porous materials are entering the market in every day products, with an attractive portfolio of properties for emerging applications ranging from health care and leisure to electronics, cosmetics, energy, agriculture, food and environmental. However, the novelty in properties and forms of aerogels makes the development of a legislative framework particularly challenging for ensuring the safe development and use of nano-enabled products. The presented safety regulatory Compendium intends to share knowledge with the international aerogels community, as well as end-users and stakeholders, on the regulatory and safe handling procedures, as best safety practices, to be followed during the production process, handling, transport and end-use of aerogel-based formulations to mitigate human and environmental risks considering lack of data availability for this purpose in general.

Flexible, Thermally Stable, and Ultralightweight Polyimide-CNT Aerogel Composite Films for Energy Storage Applications.

Polyimide (PI) aerogels are promising in various fields of application, ranging from thermal insulators to aerospace. However, they are typically in the form of a bulk monolith, which suffers from a lack of conformability and drapability. Moreover, their electrical conductivity is limited, and they mainly display an insulative behavior. These shortcomings can limit the applications of PI aerogels in energy storage systems, which require ultralightweight flexible conductive films, which at the same time offer high thermal stability, ultralow density, and high surface area. To overcome these obstacles, the present study reports the fabrication of PI-carbon nanotube (PI-CNT) aerogel composite films with varying CNT content prepared through a sol-gel preparation method, followed by a supercritical drying procedure. Compared to pristine PI aerogels, which displayed a large shrinkage and density of 18.3% and 0.12 g cm-3, respectively, the incorporation of only 5 wt % CNTs resulted in a significant reduction of both shrinkage and density to only 11.5% and 0.10 g cm-3, respectively. This suggests the importance of CNTs in improving the dimensional stability of aerogels and creating a robust network. Further characterizations showed that incorporation of 5 wt % CNTs also resulted in the highest pore volume (1.25 cm3 g-1), highest surface area (324 m2 g-1), highest real permittivity (80), highest electrical conductivity (3 × 10-1 S m-1), and ultrahigh service temperature (575 °C). It was also shown that the aerogel films can withstand a large degree of bending, can be twisted, and can be fully rolled with no obvious cracks propagated in the structure. The combined outstanding properties of the developed aerogel composite films make them promising potential candidates for supercapacitor electrodes. Therefore, the electrochemical performance of the devices based on aerogel electrodes was further studied. The device demonstrated a high energy density of 2.6 Wh kg-1 at a power density of 303.8 W kg-1. The total capacitance after 5000 cycles was 91.8% of the initial capacitance, which indicated excellent stability and durability of the device. Overall, this work provides a facile yet effective methodology for the development of high-performance aerogel materials for energy storage applications.

Linkage Effect Induced by Hierarchical Architecture in Magnetic MXene-based Microwave Absorber.

Hierarchical architecture engineering is desirable in integrating the physical-chemical behaviors and macroscopic properties of materials, which present great potential for developing multifunctional microwave absorption materials. However, the intrinsic mechanisms and correlation conditions among cellular units have not been revealed, which are insufficient to maximize the fusion of superior microwave absorption (MA) and derived multifunctionality. Herein, based on three models (disordered structure, porous structure, lamellar structure) of structural units, a range of MXene-aerogels with variable constructions are fabricated by a top-down ice template method. The aerogel with lamellar structure with a density of only 0.015g cm-3 exhibits the best MA performance (minimum reflection loss: -53.87dB, effective absorption bandwidth:6.84GHz) at a 6wt.% filling ratio, which is preferred over alternative aerogels with variable configurations. This work elucidates the relationship between the hierarchical architecture and the superior MA performance. Further, the MXene/CoNi Composite aerogel with lamellar structure exhibits >90% compression stretch after 1000 cycles, excellent compressive properties, and elasticity, as well as high hydrophobicity and thermal insulation properties, broadening the versatility of MXene-based aerogel applications. In short, through precise microstructure design, this work provides a conceptually novel strategy to realize the integration of electromagnetic stealth, thermal insulation, and load-bearing capability simultaneously.

Multi-functional and multi-scenario applications for MXene aerogels with synergistically enhanced asymmetric modules

Multi-functional and multi-scenario applications for MXene aerogels with synergistically enhanced asymmetric modules

Multifunctional ultralight magnetic CNFs/MXene/Fe3O4 nanodiscs aerogel with superior electromagnetic wave absorption performance

The design of innovative microstructures and the implementation of an appropriate multi-component strategy remain challenging in the development of advanced electromagnetic wave (EMW) absorbing materials. Achieving strong absorption and a wide effective absorption bandwidth while maintaining a thin sample thickness and low filling level is particularly demanding. Herein, a three-dimensional (3D) dielectric cellulose nanofiber (CNF)/Ti3C2Tx MXene carbon aerogel, incorporating magnetic Fe3O4 nanodiscs (NDs), was fabricated using a directional-freezing technique followed by reduction. Surprisingly, the reduction process activates the multifunctional application of aerogel with better elasticity and greatly improved electromagnetic properties, killing two birds with one stone. The structured cellular arrangement and the presence of diverse dielectric/magnetic interfaces contribute to the exceptional absorption capabilities by facilitating optimal impedance matching, enabling multiple polarization modes, and fostering electric/magnetic coupling phenomena. The aerogel exhibits excellent microwave absorption properties, characterized by its ultra-lightweight (3 % of filling ratio and 4.65 mg cm−3 of density), ultra-thin (2.18 mm), ultra-wide frequency band (6.68 GHz) and strong absorption (-56.8 dB). Additionally, the aerogel provides attractive functions such as thermal insulation and great mechanical properties (100 % recovery after 1000 cycles under 50 % strain). This study lays the groundwork for the advancement of microwave-absorbing materials, showcasing their vast potential for multifaceted applications.

Porous Aerogel Structures as Promising Materials for Photocatalysis, Thermal Insulation Textiles, and Technical Applications: A Review

Aerogels, due to their unique features like lightweight, ultra-low thermal conductivity, and design variations, have gotten a lot of interest in thermal insulation, photocatalysis, and protective areas. Besides their superior thermal properties, aerogel thermal insulation and photocatalyst materials also possess many inherent flaws, such as handling issues, high manufacturing costs, and low strength as well as toughness. The most persuasive and successful ways to improve photocatalytic and thermal insulating qualities while lowering costs are composition optimization and microstructure reconstruction. Their high surface area and porosity make them ideal for enhancing the efficiency and capacity of these devices. Research may lead to more efficient and longer-lasting energy storage solutions. This review describes the characteristics, microstructural reconstruction, design variation, and properties of all aerogel fabrication techniques and provides a comprehensive overview of scientific achievements linked to them. The effectiveness of raw material compositions, properties, and mechanical parameters are also discussed. The major goal of this review is to highlight the aerogel-based materials and design variations and to explore the most potential development trends for photocatalysis and thermal applications. The industrial as well as technical applications of silica aerogels are also highlighted. This review highlights futuristic applications of aerogel-based textile materials to alleviate the CO2 burden on our atmosphere, either by providing next-level thermal insulation or by employing them in CO2 mitigating technologies such as CO2 capture.

Tuning the Degree of Protonation to Prepare Ultra-light and High Thermal Insulation Mullite Nanofiber Aerogels

Ceramic fiber aerogels play an important role in thermal insulation due to their high specific surface area and porosity. They have great potential in aircraft, the military industry, and metal smelting. Although traditional ceramic fiber has the advantages of high-temperature resistance, its brittleness, tensile resistance, and high production cost, greatly limit the application of ceramic aerogels. Using the sol-gel method and electrostatic spinning technique, we controlled the fibers’ random winding and mechanical properties by controlling the protonation of the spinning fluid. We prepared ultralightweight, flexible, and highly insulated mullite nanofiber aerogels with a volume density as low as 7 mg / cm3, thermal conductivity as low as 27 mW m−1 K−1, excellent thermal stability at 1,300 °C, high thermal insulation and retention of up to 50% of the ceramic fiber after initial compression. This material’s fabrication process and excellent insulation properties propose new opinions on the lightweight and durable insulation materials needed for aerospace and military insulation.

Research progress on preparation, modification, and application of phenolic aerogel

Abstract Phenolic aerogel is a type of nanoporous resin-based material with low density, high specific surface area, excellent thermal insulation performance, and a high carbon residue rate which has been widely used in the field of thermal protection. However, the development of phenolic aerogel is limited by the complex and expensive preparation technique, inadequate oxidation/ablation resistance, and excessive brittleness. As a result, academic research is constantly concentrated on low-cost preparation methods and efficient modification of phenolic aerogel. This review gives a description of the preparation technology, modification techniques, and application fields of phenolic aerogel and summarizes the limitations. Now, phenolic aerogel is not applied widely due to its complex and expensive preparation technique. Moreover, phenolic aerogel shows greater brittleness and insufficient mechanical property. The prospective future developments of the materials were prospected, and the phenolic aerogel with environmental protection, efficient thermal protection, and low cost will be the mainstream research direction.

Shining Light on Carbon Aerogel Photocatalysts: Unlocking the Potentials in the Quest for Revolutionizing Solar‐to‐Chemical Conversion and Environmental Remediation

AbstractThe past few years have witnessed a surge of interest in the development of carbon aerogel‐based photocatalysts, stemming from their fascinating characteristics that encompass the inherent properties of 2D carbon‐based nanomaterials and unique 3D structural features. Benefitting from their auspicious physicochemical characteristics, including low density, abundant active sites, and remarkable electrical conductivity, carbon aerogels have emerged as promising candidates for photocatalysis in energy and environmental applications. Thus, this review presents a panorama of state‐of‐the‐art advancements underlying the synthesis and modifications of carbon aerogel‐based nanocomposites for enhanced performance in photocatalytic applications. The synthetic strategies followed by the unique roles of carbon aerogel are highlighted to decipher the auspicious roles of carbon aerogels in bolstering photocatalytic activity. Additionally, the fundamental mechanism behind carbon aerogel‐based photocatalysts as well as their modifications are thoroughly discussed. Thereafter, the works on the photocatalytic applications of carbon aerogel in solar‐driven hydrogen evolution, CO2 reduction, pollutant decontamination, and bacteria inactivation, in the past 5 years are summarized with insights into charge dynamics being unveiled. Lastly, this review will prospect the ongoing challenges and future outlook of carbon aerogel‐based heterostructures in photocatalysis, aiming to facilitate the development of carbon aerogel‐based photocatalysts at the forefront of this research.

Thermal Insulation Mechanism, Preparation, and Modification of Nanocellulose Aerogels: A Review.

Energy problems have become increasingly prominent. The use of thermal insulation materials is an effective measure to save energy. As an efficient energy-saving material, nanocellulose aerogels have broad application prospects. However, nanocellulose aerogels have problems such as poor mechanical properties, high flammability, and they easily absorbs water from the environment. These defects restrict their thermal insulation performance and severely limit their application. This review analyzes the thermal insulation mechanism of nanocellulose aerogels and summarizes the methods of preparing them from biomass raw materials. In addition, aiming at the inherent defects of nanocellulose aerogels, this review focuses on the methods used to improve their mechanical properties, flame retardancy, and hydrophobicity in order to prepare high-performance thermal insulation materials in line with the concept of sustainable development, thereby promoting energy conservation, rational use, and expanding the application of nanocellulose aerogels.

Preparation of aerogels from corn stalks and research on their properties and gelation behavior

Corn straw is a kind of agricultural biomass waste produced by the corn crop. It is a question of how to make effective use of this waste resource. Biomass aerogel is a good adsorbent which can be used to deal with water pollution. The direct use of non-component separated maize straw as the raw material in this paper can effectively reduce the experimental cost, simplify the experimental procedures and make efficient use of maize straw compared to traditional cellulosic raw materials. The inorganic salt lithium bromide (LiBr) solution was used as the solvent, and the environmentally friendly corn stover whole component aerogels (CA) with excellent performance were prepared by solvent replacement and freeze-drying. The optimum process for the preparation of aerogels was obtained using a single factor test method: 1:200, 150 ℃, 40 min, 70 wt% LiBr. The full-component aerogels from maize straw contained cellulose, hemicellulose and lignin, which indicated that the maize straw was effectively utilised. CA has a three-dimensional network pore structure, mainly composed of micropores and mesoporous pores. It has ultra-low density (9 mg/cm3) and excellent adsorption capacity for methylene blue and soybean oil (123.59 mg/g, 103.58 g/g). At the same time, the Rheolaser Master Microrheological (RMM) analyzer of French Formulaction Company was used to investigate the changes in solution gel process. The mean azimuth shift (MSD) curve of the sample was measured by optical microrheometer. The elastic factor (EI), macroscopic viscosity factor (MVI), solid-liquid equilibrium point (SLB), and photon free path (I*) values of the samples were calculated to explore the microstructure and rheological characteristics of the samples during the gel process. The gel behaviour and processes have been explored based on the analysis of these parameters. Potential applications of whole-component aerogels from corn stalks include building insulation, thermal insulation, light-blocking materials, and packaging materials.

Polybenzoxazine aerogels fabricated by an aqueous solvent sol–gel method for thermal insulation

Polybenzoxazine (PBz) aerogels with outstanding mechanical properties and thermal insulation have attracted significant attention because of their classification as the most advanced and efficient thermal insulation material. However, the complex and environmentally unfriendly preparation technology has consistently hindered the performance improvement and broad practical applications of PBz aerogels. Herein, we report a facile preparation method of PBz aerogels through an aqueous solution system and ambient pressure drying (APD), thereby overcoming the limitations of the conventional methods. The resulting PBz aerogel exhibits lightweight (0.194 g cm−3), efficient thermal insulation, low thermal conductivity (0.0313 W m−1 K−1), self-extinguishing, super-hydrophobicity (contact angle of 148°), and remarkable mechanical properties. This study proposes a cutting-edge approach to fabricate PBz aerogels, which further amplifies their potential application in the field of thermal insulation.

Controllable preparation of aerogel/expanded perlite composite and its application in thermal insulation mortar

The extremely low strength and high cost of aerogel limit its applicability in energy-efficient buildings. In this paper, the controllable preparation method of aerogel/expanded perlite (AEP) was developed, and the particle gradation effect on AEP thermal insulation mortar (AEPM) was assessed, which provided an effective way for the application of aerogel and AEP in buildings. The results showed that the acid/base catalysis two-step method was imperative for preparing AEP. It was also found that the pH of SiO2 hydrosol should be controlled within 3.2–3.5, and the corresponding gel time of SiO2 hydrosol was 30–90 min. The impregnation-adsorption process of EP adsorbing SiO2 hydrosol should be completed before the initial viscosity of 3 mPa·s changes. The amount of SiO2 hydrosol adsorbed by EP had a logarithmic relationship with the adsorption time under the adsorption of ambient pressure (AP), whereas its linear relationship with the adsorption pressure under the adsorption of vacuum pressure (VP) was found. The pores of expanded perlite (EP) were filled with well-structured aerogel due to the controlled preparation of AEP. Thus, the AEP bulk density increased by 24%-50% compared with EP. However, the thermal conductivity decreased by 14.6%-31.8%, and the particle strength of AEP was not significantly improved compared with that of EP. AEPM prepared by AEP showed typical characteristics of high strength and low thermal conductivity. The compressive strength of AEPM was 6.5% lower than that of EPM but more than twice that of AERM, while the corresponding water absorption and thermal conductivity were 27.6% and 26.6% lower than EPM. As a new nano-micron porous composite, AEP has great applicability in developing thermal insulation materials, phase change materials, and adsorption materials.

Visualization Analysis and Knowledge Mapping the Research of Aerogels Applied in Buildings

With the deepening of aerogel research and the popularization of its application, the demands for energy saving in the construction field has brought aerogels into the limelight. To explore state-of-the-art research and development trends related to aerogels applied in construction, CiteSpace was used to conduct a quantitative analysis based on the Web of Science core database. Results show that: (1) in the past 10 years, the number of papers on aerogels in the field of constructions has increased significantly; (2) the top producing countries in the aerogel field are mainly China and the United States, and the top two research institutions are all Chinese institutions (Univ Sci & Technol China and Chinese Acad Sci); (3) the main publishing journals are ENERGY AND BUILDINGS, CONSTRUCTION AND BUILDING MATERIALS, and CHEMICAL ENGINEERING JOURNAL; (4) the hot keywords are thermal insulation, silica aerogel, thermal conductivity, phase change material, mechanical property, graphene aerogel, self-assembly, energy saving, etc.; (5) aerogel is mostly used in building insulation, mainly in the form of aerogel glass, aerogel mortar, aerogel felt, and aerogel coating. In summary, in addition to systematically strengthening theoretical research, it is necessary to optimize the technical process and reduce costs in order to effectively promote aerogels in construction energy conservation and carbon reduction. Through this study, the current situation, hot spots, and development trend of aerogel application in construction can be revealed systematically. Overall, this study helps advance research on aerogels applied in buildings and help in tackling energy efficiency challenges.