Applications Of Aerogels Research Articles

Hydrophobic-oleophilic gamma-irradiated modified cellulose nanocrystal/gelatin aerogel for oil absorption

This study highlights the potential use of cellulose nanocrystals (CNCs) from kenaf fiber as a dominant phase for aerogel application. CNCs were modified with methyltrimethoxysilane (MTMS) using the sol-gel method and bound with gamma-irradiated cross-linked gelatin. The properties of the aerogel were studied using Fourier transform infrared (FTIR) spectroscopy, transmission electron microscopy (TEM), field emission scanning electron microscopy (FESEM), and water contact angle (WCA). Compression and oil absorption tests were performed to study the aerogels' mechanical and oil absorption properties. A decrease in the OH peak and improved hydrophobicity of CNCs in CNC-MTMS suggested the successful grafting of MTMS onto CNCs, as shown in the FTIR and WCA analyses. Several absorption peaks in the FTIR spectrum shifted, disappeared, or reduced, implying a formation of crosslink between gelatin molecules and hydrogen bonding between CNC and gelatin. FESEM micrographs showed well-organized pores in the gamma-irradiated aerogel, which contribute to increased compressive strength. The oil absorption test indicated that gamma-irradiated CNC-MTMS/gelatin could be a good oil absorbent. Furthermore, this aerogel showed good reusability, where only 4 % of crude oil absorption reduction occurred by the eighth cycle. The combined properties of these aerogel materials can provide good mechanical and oil absorption performance.

Industrial application of SiO2 aerogel prepared by supercritical ethanol (SCE) drying technique as cold and heat insulation materials

Industrial application of SiO2 aerogel prepared by supercritical ethanol (SCE) drying technique as cold and heat insulation materials

Effect of silica aerogel on thermal insulation and acoustic absorption of geopolymer foam composites: The role of aerogel particle size

Silica aerogel features super thermal insulating and excellent sound absorption. Although the application of silica aerogel in building materials for energy saving has been investigated recently, the role of aerogel particle size on geopolymer foam render can be crucial but is rarely studied. In this research, four kinds of silica aerogel with different particle sizes (2–40 μm, 100–700 μm, 100–1200 μm, 700–4000 μm) are applied in geopolymer foam aerogel render (GFAR) to improve the thermal insulation and acoustic absorption performance. Results show that larger silica aerogel particles are more beneficial for acoustic absorption and thermal insulation while smaller aerogel particles are less effective for insulation properties. The microstructure of GFAR is investigated in-depth with micro-CT, optical microscopy and ultrasonic pulse velocity test. The mechanism of the improved performance of GFAR with different silica aerogel is explained. The optimal geopolymer foam aerogel render (GFAR) reaches a thermal conductivity of 0.133 W/(m·K), an average value of acoustic absorption coefficient of 0.51 with a density of 715.2 kg/m3. The result of this study is essential to enlighten the use of larger silica aerogel particles in geopolymer foam render, focusing on a low dosage of silica aerogel while utilize its full benefit.

Processing of aerogels and their applications toward CO2 adsorption and electrochemical reduction: a review.

Aerogels are a unique class of nanoporous ultralight materials exhibiting wide range of textural characteristic properties and tunable porosities. Due to their remarkable features such as low density, high surface area, low refractive index, small thermal conductivity, low dielectric constant and low sound velocity, they exhibit a wide range of applications in different areas such as electronics, thermal and acoustic insulation, chemistry, biomedicine and optics. The special advantages of these materials are that they can be produced in different forms such as monoliths/granular, bead/microspheres, thin films or sheets and as blankets. Aerogels are found to be potential materials for the removal of CO2 through adsorption or electrochemical reduction. There is a plethora of research on different kinds of aerogels used for CO2 adsorption process. Research has been going on toward the development of aerogel-based electrocatalyst, which can be used for valorization of CO2 through electrochemical reduction methods. Although most of the review papers have covered applications of aerogels in CO2 capture, very few discuss the processing of aerogels, more so on their applications in CO2 valorization. In this review, we have collated literature of different forms of aerogels currently available and the steps involved in their fabrication process. In addition, we have covered applications of aerogels in CO2 capture. Furthermore, we focussed on the basic principles involved in the development of an aerogel electrocatalyst as well as recent developments of aerogels in electrochemical CO2 reduction.

Research Development in Silica Aerogel Incorporated Cementitious Composites-A Review.

This paper presents an analysis of research results for silica aerogel cement composites over the past twenty years. Recently, two trends in the development of these composites have been noted, towards structural applications and towards ultralight composites for coatings and renders. Ongoing research shows that important aspects of cementitious composites with good mechanical performance are the proper selection of aggregates and improved adhesion at the silica aerogel–cement binder interface, which will guarantee high compressive strength with the lowest possible thermal conductivity. The best physicomechanical performance of aerogel cement composites with low thermal conductivity below 0.03 W/(m·K) was obtained when cenospheres and aerogel were used in a weight percentage of 5%. In turn, the prerequisites for using aerogel cement composites as coatings for energy-efficient building façades are the use of large amounts of silica aerogel as a substitute for lightweight aggregates or the selection of an optimal composition of lightweight aggregates and aerogel, ensuring the lowest possible thermal conductivity coefficient. Other important standpoints are water transport and moisture protection of the silica aerogel-based coatings. Therefore, in recent years, more and more elements of the hygrothermal performance, porosity and durability of silica aerogel cement composites have been developed. The article also points out the weaknesses of the application of silica aerogel in the cement matrix, the most important of which are the lack of adhesion at the boundary of the aerogel–cement binder, the increased porosity of the composite, the high water absorption capacity and the significant decrease in compressive strength with large volumes of silica aerogel. Solving these issues will certainly contribute to the wider applicability of these materials in the construction industry.

Biomedical Applications of Polyurethane Hydrogels, Polyurethane Aerogels, and Polyurethane-graphene Nanocomposite Materials.

The emergence of new diseases poses therapeutic challenges in modern medicine. Polyurethane hydrogels that comprise polyol, copolymer and extender could be prepared from diverse chemical compounds with adjuvants such as ascorbic acid and sorbitol, among others. Their mechano-physicochemical properties are functions of their biological activities. Therefore, there is a need to assess their therapeutic potentials. Relevant literature on the synthesis and medical uses of polyurethane-hydrogels, polyurethane- aerogels, and polyurethane-graphene nanocomposite materials was searched in order to identify their sources, synthesis, mechanical and physiochemical properties, biomedical applications, chirality, and the relevance of Lipinski's rule of five in the synthesis of oral polyurethane nanocomposite materials. The prepared hydrogels and aerogels could be used as polymer carriers for intradermal, cutaneous, and intranasal drugs. They can be fabricated and used as prosthetics. In addition, the strength modulus (tensile stress-tensile strain ratio), biodegradability, biocompatibility, and nontoxic effects of the polyurethane hydrogels and aerogels are highly desirable properties. However, body and environmental temperatures may contribute to their instability; hence, there is need to improve the synthesis of aerogels and hydrogels of polyurethane in order to ensure that they can last for many years. Alcoholism, diabetes, pyrogenic diseases, mechanical and physical forces, and physiological variability may also reduce the life span of polyurethane aerogels and hydrogels. Synthesis of polyurethane hydrogel-aerogel complex that can be used in complex, rare biomedical cases is of paramount importance. These hydrogels and aerogels may be hydrophobic, hydrophilic, aerophobic-aerophilic or amphiphilic, and sometimes lipophilic, depending on structural components and the intended biomedical uses. Polyurethane graphene nanocomposite materials are used in the treatment of a myriad of diseases, including cancer and bacterial infection.

Progress and perspective in mechanically robust carbon aerogels

Carbon aerogels (CAs) are emerging carbon-based cellular materials with high porosity, low density, and a variety of functions. The combination of all these unique properties contributes to their wide applications in flexible sensors, energy devices, acoustic devices, and environmental applications. However, their wide applications are strictly limited by poor mechanical robustness. The existing conflicts between mechanical robustness and the sparse network of porous materials have never received due attention. Good robustness could ensure structural integrity and performance stability for practical applications of aerogels. Here, we discuss recently emerged strategies for optimizing mechanical robustness, including cell-wall strengthening, cell-wall orientation, pore topology control, and joint reinforcement. Particularly, we conclude advanced design principles to achieve stretching elasticity of CAs without introducing intrinsically stretchable elastomers. In addition, we briefly overview the recent applications of robust CAs and provide an outlook on the open questions for obtaining more mechanically robust CAs.

All-Ceramic and Elastic Aerogels with Nanofibrous-Granular Binary Synergistic Structure for Thermal Superinsulation.

High-performance thermally insulating ceramic materials with robust mechanical properties, high-temperature resistance, and excellent thermal insulation characteristics are highly desirable for thermal management systems under extreme conditions. However, the large-scale application of traditional ceramic granular aerogels is still limited by their brittleness and stiff nature, while ceramic fibrous aerogels often display high thermal conductivity. To meet the above requirements, in this study, ceramic nanofibrous-granular composite aerogels with lamellar multiarch cellular structure and leaf-like fibrous-granular binary networks are designed and fabricated. The resulting composite aerogels possess ultralow weight, superelasticity with recoverable compression strain up to 80%, and large mechanical strength. Furthermore, excellent fatigue resistance with 1.2% plastic deformation after 1000 cyclic compressions, temperature-invariant dynamic mechanical stability from -100 to 500 °C, and an operational temperature range from -196 to 1100 °C are successfully achieved in the proposed composites. The nanosized silica granular aerogels are assembled into a leaf-like shape and wrapped around the fibrous cell walls, endowing low thermal conductivity (0.024 W m-1 K-1) as well as favorable high-temperature thermal superinsulation properties. Benefiting from the favorable compatibility, the present strategy for nanofiber-granular composite ceramic aerogels provides a dominant route to produce thermally insulated and mechanically robust composite cellular materials for use in harsh environments.

Nanocellulose-based aerogels with devisable structure and tunable properties via ice-template induced self-assembly

Nanocellulose-based aerogels are widely used in various fields due to the lightweight and porous features. The pore structure plays a decisive role in the performances, but controllable fabrication of the nanocellulose-based aerogel with a tunable structure is still a challenge. Herein, we reported a facile approach to prepare nanocellulose aerogel with a designable pore structure by ice-induced self-assembly. The relationship between the properties and structure was investigated by simply tuning factors such as temperature gradient, freezing rate, infiltration interface, and solute concentration. The as-prepared aerogel exhibited regulable density (2.35–15.96 mg/cm3), pore size (2 nm-500 µm), and desirable flexibility which is suitable for thermal insulation application. The research provides new insight into the controllable preparation and functional application of nanocellulose-based aerogels.

Recent Progress in Modification Strategies of Nanocellulose-Based Aerogels for Oil Absorption Application.

Oil spills and oily wastewater have become a major environmental problem in recent years, directly impacting the environment and biodiversity. Several techniques have been developed to solve this problem, including biological degradation, chemicals, controlled burning, physical absorption and membrane separation. Recently, biopolymeric aerogels have been proposed as a green solution for this problem, and they possess superior selective oil absorption capacity compared with other approaches. Several modification strategies have been applied to nanocellulose-based aerogel to enhance its poor hydrophobicity, increase its oil absorption capacity, improve its selectivity of oils and make it a compressible and elastic magnetically responsive aerogel, which will ease its recovery after use. This review presents an introduction to nanocellulose-based aerogel and its fabrication approaches. Different applications of nanocellulose aerogel in environmental, medical and industrial fields are presented. Different strategies for the modification of nanocellulose-based aerogel are critically discussed in this review, presenting the most recent works in terms of enhancing the aerogel performance in oil absorption in addition to the potential of these materials in near future.

Nanoporous Kevlar Aerogel Confined Phase Change Fluids Enable Super‐Flexible Thermal Diodes

AbstractAerogels have demonstrated tremendous potentials for various applications, including thermal insulation, environmental protection, and separation. However, aerogels as porous frameworks to host functional liquids (such as phase change fluids, PCFs) is a more promising application, attributing to their large specific surface area, high porosity, and strong capillary force. Herein, the original aramid nanofiber (OANF, i.e., Kevlar) aerogel film and the densified ANF (DANF) aerogel film are fabricated and thereafter applied to confine phase change fluids, poly (N‐isopropylacrylamide) (PNIPAM) solution and molten eicosane (C20), respectively, to make super‐flexible OANF‐PNIPAM and DANF‐C20 films accordingly. These two films exhibit reversely temperature‐dependent thermal conductivity with close phase change temperature to each other. Therefore, flexible thermal diodes operating with terminals of OANF‐PNIPAM film and DANF‐C20 film are proposed and fabricated, showing excellent flexibility (420 µm in curvature radius) and robustness (≥7.2 MPa in tensile strength) as well as the maximum thermal rectification ratio of 2.0. This work paves a way for expanding the applications of Kevlar aerogel confined phase change fluids, as well as provides a promising strategy for designing more practical thermal diodes and thermal devices.

One-pot preparation of surface vulcanization Co-Fe bimetallic aerogel for efficient sulfadiazine degradation

• Persulfate activation of CoFe-0.2S aerogels improves with increasing S content. • Synergy of cobalt-iron is conducive to accelerate the generation of radicals. • Delocalized electrons in surface FeS n accelerate electron transfer of PDS activation. • Proposed reaction pathway for the oxidation of sulfadiazine. A novel magnetic surface vulcanized cobalt-iron aerogel (CoFe-S MA) with a self-supporting, crosslinked bimetallic nanowire structure was fabricated via NaBH 4 -mediated gelation followed by in-situ vulcanization with Na 2 S solution, which showed efficient sulfadiazine (SDZ) degradation through peroxodisulfate (PDS) activation. The optimized CoFe-0.2S aerogels exhibited the best degradation performance (99.8%) for SDZ (10 mg/L, 100 mL) within 15 min, and the total organic carbon (TOC) removal efficiency reached 53%. The excellent degradation performance was attributed to the accelerated redox process and rapid formation of sulfate radical (SO 4 ·- ) caused by bimetal synergistic effect, as well as the sufficient exposed active sites provided by the self-supporting hierarchical porous structure of the aerogel. Compared with CoFe-MAs, electrochemical impedance spectroscopy (EIS) demonstrated lower resistance and more rapid charge transfer of CoFe-S MAs, which was ascribed to the presence of delocalized electrons in iron sulfides layer. A high turnover frequency (TOF) of 4.0 L∙min −1 ∙g −1 was achieved due to that the reduction effect of S 2- on the surface promoted the regeneration of Fe and Co active species. Electron paramagnetic resonance (EPR) and quenching experiments revealed the dominant reactive oxide species (ROS) to be SO 4 ·- , ‧OH, and Fe (Ⅳ). This work paves the way for the application of metal aerogels in the field of advanced oxidation process based on sulfate radical (AR-AOPs).

Research progress and applications of silica-based aerogels - a bibliometric analysis.

Silica aerogels are three-dimensional porous materials that were initially produced in 1931. During the past nearly 90 years, silica aerogels have been applied extensively in many fields. In order to grasp the progress of silica-based aerogels, we utilize bibliometrics and visualization methods to analyze the research hotspots and the application of this important field. Firstly, we collect all the publications on silica-based aerogels and then analyze their research trends and performances by a bibliometric method regarding publication year/citation, country/institute, journals, and keywords. Following this, the major research hotspots of this area with a focus on synthesis, mechanical property regulation, and the applications for thermal insulation, adsorption, and Cherenkov detector radiators are identified and reviewed. Finally, current challenges and directions in the future regarding silica-based aerogels are also proposed.

Preparation and properties of reduced graphene oxide-carbon nanotubes aerogel/cotton flexible composite fabric with electromagnetic shielding function

The electromagnetic pollution has become a serious problem with the rapid development of electromagnetic industry. The present work prepared an electromagnetic interference (EMI) functional composite fabric. Reduced graphene oxide (rGO)-carbon nanotubes (CNTs) aerogel with three-dimensional (3-D) architecture were coated to the cotton fabric with the assistance of waterborne polyurethane (WPU). The structure of graphene aerogel was affected by the amount of CNTs. Small amount of CNTs is helpful to minish the pore size of aerogel and thus improve the EMI value. However, it has been shown that excess CNTs will destroy the 3-D architecture of graphene aerogel. Result shows that the EMI shielding effectiveness exceeded 35 dB when the weight ratio of rGO and CNTs was 7:3, and EMI value of the corresponding composite fabric samples reached 34 dB. Consequently, excellent EMI results were obtained by the unique 3-D rGO-CNTs aerogel in the case of a small nano-carbon material amount. The present work will be expected to make contributions to the practical application of rGO-CNTs aerogel.

Aerogels for Biomedical, Energy and Sensing Applications.

The term aerogel is used for unique solid-state structures composed of three-dimensional (3D) interconnected networks filled with a huge amount of air. These air-filled pores enhance the physicochemical properties and the structural characteristics in macroscale as well as integrate typical characteristics of aerogels, e.g., low density, high porosity and some specific properties of their constituents. These characteristics equip aerogels for highly sensitive and highly selective sensing and energy materials, e.g., biosensors, gas sensors, pressure and strain sensors, supercapacitors, catalysts and ion batteries, etc. In recent years, considerable research efforts are devoted towards the applications of aerogels and promising results have been achieved and reported. In this thematic issue, ground-breaking and recent advances in the field of biomedical, energy and sensing are presented and discussed in detail. In addition, some other perspectives and recent challenges for the synthesis of high performance and low-cost aerogels and their applications are also summarized.

Structure Control and Application of Nanocellulose Aerogels

Nanocellulose is a kind of renewable green material that comes mainly from plants. Nanocellulose aerogels have high porosity, excellent flexibility, and low thermal conductivity. They have broad application prospects in building insulation, sewage treatment, energy storage, aerospace, and other fields. The structure of nanocellulose aerogels has a significant influence on their properties, which further affects their application. In this paper, the present regulation methods of nanocellulose aerogel structure are reviewed, and the most widely used fields of nanocellulose aerogel are introduced in detail. In addition, research for improving the structure and applications of nanocellulose aerogels in the future is proposed.

Recent Progresses in Eco-Friendly Fabrication and Applications of Sustainable Aerogels from Various Waste Materials.

Tons of waste from residential, commercial and manufacturing activities are generated due to the growing population, urbanization and economic development, prompting the need for sustainable measures. Numerous ways of converting waste to aerogels, a novel class of ultra-light and ultra-porous materials, have been researched to tackle the issues of waste. This review provides an overview of the status of aerogels made from agricultural waste, municipal solid, and industrial waste focusing on the fabrication, properties, and applications of such aerogels. The review first introduced common methods to synthesize the aerogels from waste, including dispersion and drying techniques. Following that, numerous works related to aerogels from waste are summarized and compared, mainly focusing on the sustainability aspect of the processes involved and their contributions for environmental applications such as thermal insulation and oil absorption. Next, advantages, and disadvantages of the current approaches are analyzed. Finally, some prospective waste aerogels and its applications are proposed. Graphic

Recent progress and applications of aerogels in China

Recent progress and applications of aerogels in China

Simple ultrasonic-assisted approach to prepare polysaccharide-based aerogel for cell research and histocompatibility study

Salecan, a water-soluble microbial polysaccharide with attractive biocompatible characteristics, is very suitable for aerogel fabrication. However, the practical application of salecan-based aerogels for cell culture was limited by complicated preparation method, lack of cell anchorage signals, and the ability to modulate this properly. Here, a smart aerogel was designed by ultrasonic-assisted self-assembly of salecan and cationic starch (CAS) without any organic and toxic crosslinkers. The ultrasound waves generated a marked impact on self-assemble process by means of ultrasonic cavitation. Aerogel network was produced by strong electrostatic attractions between the polysaccharides. Especially, salecan/CAS ratio can be precisely modulated to tailor the hydrophilicity, mechanical stiffness, and morphologic property. The specific surface area of the aerogels gradually increased with the increase in salecan/CAS ratio. These aerogels were non-cytotoxic, and the incorporation of salecan into them promoted cell-matrix interactions by directionally supporting cell adhesion and proliferation. Most strikingly, in vivo experiment revealed that the histological features in the main organs of the mice were similar to those observed in the PBS-treated control group, and no sign of the histopathological abnormality or tissue destruction was observed, indicating the excellent histocompatibility of the aerogels. This study offered a new and powerful avenue to fabricate functional biomaterial.

Acidic and alkaline gas sensitive and self-healing chitosan aerogel based on electrostatic interaction

Gas pollution is a serious problem. More attention has been paid to the detection and monitoring of toxic and harmful gases, and it is urgently needed for a sensor that could simultaneously identify and distinguish between acid and base gases. Based on the electrostatic interaction resulting from amidogen of chitosan (CS) and carboxylic groups of itaconic acid (IA), we successfully prepared a series of biomass aerogels (CS-IA aerogels) that could respond to acidic and alkaline gases with different concentrations. The acidic and alkaline gases could be easily detected and distinguished by changing the content of IA in CS-IA aerogels. Moreover, the electrostatic interactions could also endowed CS-IA aerogels with self-healing ability in the breaks at room temperature. After self-healing, CS-IA aerogels still sensitively answered to acidic and alkaline gases. CS-IA aerogels with sensitivity to acid-base gas and self-healing performance has been suggested to be promising candidates as application of multi-functional aerogels.