Fabrication Of Aerogels Research Articles

Citric acid modification in fabrication of composite aerogels from cigarette butts and chitosan for enhancing dye removal efficiency

Citric acid modification in fabrication of composite aerogels from cigarette butts and chitosan for enhancing dye removal efficiency

Superior flame retardancy, thermal insulation, and mechanical properties of konjac glucomannan/sodium alginate biomass aerogel modified by supramolecular assembled phytic acid-melamine nanosheet

The development of biomass-based eco-friendly aerogel with superior flame retardancy, thermal insulation, and mechanical properties at the same time has long been a tough challenge. In this study, the polysaccharide-based aerogels composed of konjac glucomannan, sodium alginate, and supramolecular assembled melamine phytate (MPA) nanosheets were successfully fabricated through the freeze-drying method. Owing to the excellent charcoal-forming and non-combustible gas-releasing effect of MPA nanosheets, the thermal stability and flame retardancy properties of the aerogels were both significantly enhanced, with the highest limiting oxygen index value reaching 42.4 %. Meanwhile, appropriate MPA embedded in the pore walls greatly enhanced the compressive strength of the aerogel (364.9 kPa) and can withstand >7100 times its weight without visual deformation. Moreover, the thermal insulation effect was quite attractive with a thermal conductivity of 0.0385–0.0420 W/mK. The present work provided an environmentally friendly method for the fabrication of multifunctional sustainable fire-resistant aerogels, which showed promising prospects in the future.

Sub−1 nm Nanowire Aerogels

AbstractThe emerging sub−1 nm nanowires (SNWs) have received tremendous attention given their intriguing properties and broad applications attributable to their ultrasmall feature size. However, applying SNWs in microstructure‐preserving macroscopic functional materials (e.g., aerogels) remains challenging because the solvents used for preparing SNWs are not compatible with conventional supercritical drying or freeze‐drying techniques. In this study, the fabrication of SNW aerogels (SNWAs) is pioneered by developing a nonpolar solvent‐based freeze‐casting strategy. Cyclohexane, a nonpolar solvent with a freezing point (6.5 °C) comparable to that of water, is selected as a reaction and drying medium to assemble various SNWs. The resulting self‐standing SNWAs display low density, excellent hydrophobicity and lipophilicity, and tunable luminescent color. This strategy not only introduces a new aggregation form of SNWs but also provides a creative perspective on synthesizing aerogel structures from sub−1 nm building blocks.

Near-net-shape fabrication of SiC aerogels through in-situ carbonisation of Si

SiC aerogels are excellent porous materials with extensive application prospects. However, their ultra-low density and extremely low strength make them challenging to process. Near-net-shape fabrication is crucial to overcome the manufacturing difficulties of SiC aerogels with complex-shaped. In this work, we propose a novel method for preparing near-net-shape SiC aerogels through the in-situ carbonisation of Si, enabling the fabrication of aerogels with complex geometries. The as-prepared SiC aerogels consist of SiC nanowires (SiCnw) and SiC nanoparticles (SiCnp), which have ultra-low density, excellent thermal insulation, and robust high-temperature stability.

Innovative fabrication of ultrasensitive and durable graphene fiber aerogel for flexible pressure sensors

Elastic graphene aerogels have promising applications in flexible pressure sensors. However, it is still difficult to prepare graphene aerogels with high sensitivity and reliable mechanical stability due to the challenge in structural regulation. This study proposes an innovative method for preparing graphene aerogel by combining wet-electrospinning and freeze-drying. The resultant is a cotton-like 3D graphene fiber aerogel (GFA) with soft exterior but firm essence. The aerogel assembled of randomly stacked 1D graphene fiber, exhibiting softness and low compressive strength, thus ensuring the highly sensitive. Furthermore, this graphene fiber possessing strong mechanical properties after high-temperature thermal annealing, guarantees the fatigue resistance and elasticity of the aerogel. Therefore, the assembled GFA-based pressure sensor is ultrasensitive with a high sensitivity of 18.55 kPa−1 and a low detection limit of 2 Pa. Additionally, it has a rapid response time of 2 ms and maintains good stability even after 3000 cycles. The exceptional properties of GFA suggest its immense potential for application in human health monitoring and motion detection. In addition, the wet-electrospinning preparation of GFA provides a new strategy for the fabrication of graphene aerogels.

Continuous Rapid Fabrication of Ceramic Fiber Sponge Aerogels with High Thermomechanical Properties via a Green and Low-Cost Electrospinning Technique.

Ceramic aerogel is an appealing fireproof and heat-insulation material, but synchronously improving its mechanical and thermal properties is a challenge. Moreover, the expensive discontinuous processing techniques inhibit the large-scale fabrication of ceramic aerogels. Here, we propose a water-based electrospinning method, based on the hydrolysis and condensation reactions of ceramic precursor salts themselves, for the continuous and rapid (0.025 m3/min) fabrication of ceramic fiber sponge aerogels with dual micronano fiber networks, which show synchronous enhanced fireproof, thermal insulation, and resilience performance. The elastic ceramic micro/nano fiber sponge aerogels contain robust silica-based microfibers as a firm skeleton and alumina-based nanofibers as elastic thermal insulation filler. The sponges have a high porosity of >99.8%, a low mass density (6.21 mg/cm3), a small thermal conductivity (0.022 W/m·K), and a large compression strength (21.15 kPa at 80% strain). The ceramic fiber sponges can effectively prevent the propagation of thermal runaway when a lithium battery experiences catastrophic thermal shock (>1000 °C) in the power battery packs. The proposed strategy is feasible for low-cost and rapid synthesizing ceramic aerogels toward effective battery thermal management.

Polypropylene aerogel‐based composites with paraffin and MWCNTs as phase change materials

AbstractThe development of energy storage materials is crucial for effective energy management. In this study, we present the creation of a composite material comprising polypropylene (PP) aerogel, paraffin, and multi‐walled carbon nanotubes (MWCNTs) as a phase change material (PCM). Our process begins with the dissolution of PP granules, serving as the foundational step. Subsequently, various antisolvents are systematically employed to induce the formation of PP gels. The process culminates in the fabrication of aerogels through the established freeze‐drying technique. Importantly, our examination of porosity highlights the significant impact of antisolvent selection on the pore structure and specific surface area of the resulting aerogels. Our weight measurements demonstrate the remarkable capacity of the lightweight PP aerogel, characterized by substantial porosity and inherent hydrophobicity, to adsorb paraffin, capturing up to five times its weight. These findings are substantiated through structural analyses, including Fourier‐transform infrared spectroscopy (FTIR) and X‐ray diffraction (XRD). Thermal analysis of the PP/PCM/MWCNTs composites reveals the achievement of the highest enthalpy, reaching 125 J g−1, representing a modest 13% reduction compared to pure paraffin. Furthermore, all samples exhibit exceptional thermal stability even after 50 thermal cycles. Notably, Xenon flash analysis (XFA) shows an approximate 800% increase in thermal conductivity compared with pure paraffin and a substantial 35% increase compared to PP/paraffin composites. In conclusion, our lightweight aerogel‐based PCM demonstrates great promise for various thermal management applications.Highlights Cost‐effective PP aerogel has a great potential for hosting paraffin as PCM. The type of antisolvent could have a huge effect on PP aerogel's structure. PP aerogel/Paraffin/MWCNT could effectively enhance thermal conductivity. Available PP/Paraffin/MWCNT has a great potential for PCM applications.

Fabrication of MOF-rGO aerogels to enhance electromagnetic wave absorption by adjusting the morphology and structure of MOFs by electron transfer

Graphene and its derivatives have become the star materials in the field of electromagnetic wave (EMW) absorption, and have been widely studied because of their unique structure and excellent properties. However, the high electrical conductivity of graphene-based material leads to poor impedance matching performances, so it often needs to be annealed at high temperatures, which is a intricate procedure and cause the waste of energy. Herein, we develop a convenient strategy to synthesize metal organic framework-reduced graphene oxide (MOF-rGO) aerogels through facile hydrothermal and freeze drying procedure. Firstly, the excessive electrons on graphene can be transferred to MOF, in this way, no annealing is needed. Secondly, the morphology and structure of MOF can be regulated electronically to endow the material with rich heterojunction interfaces and enhance its interfacial polarization. Thirdly, the synthesized aerogels satisfy the requirements of thin thickness, low density and light weight. The fabricated Ni-MOF-rGO and FeNi-MOF-rGO aerogels exhibit remarkable EMW absorption performances with strong reflection loss (RL) and broad effective absorption band (EAB) at the thickness of 2.4 (−47.8 dB and 7.84 GHz) and 2.9 mm (−48.3 dB and 8.32 GHz) whereas the filling contents are just 5 %. Moreover, the attenuation capacity of the fabricated aerogels are verified through the radar-section simulation and the interfacial polarization loss are confirmed by the COMSOL analogue simulation. In a word, this work provides a new afflatus and inspiration for the design of graphene-based EMW absorption materials.

Fabrication and characterization of porous pectin-based aerogels for drug delivery

Aerogels are renowned for their exceptional characteristics such as high porosity and ultra-low density. Among these, pectin aerogels, offering biodegradability, low toxicity, and versatility, are prominent candidates for innovative biomedical materials. This study focused on synthesizing pectin-based aerogels as carriers for ibuprofen and diclofenac sodium. Hydrogels were formed by combining a low methoxy pectin with calcium chloride solution, followed by dehydration and drying using either supercritical carbon dioxide (scCO2) or freeze–drying. Comparative analysis showed scCO2-dried aerogels exhibited slightly less shrinkage (0.27 %) than freeze–dried counterparts. Both types showed high porosity and mesoporous characteristics. However, scCO2-dried aerogels demonstrated higher specific surface area, pore volume, and smaller pore diameter. FTIR spectra indicated no interaction between the drugs and pectin-based aerogels. The loading of ibuprofen in scCO2-dried, pectin-based aerogels at 90, 95, and 100 bar were 60.0 %, 59.9 %, and 52.1 %, respectively, and the solution loading of diclofenac sodium was 38.37 %. At 90, 95, and 100 bar, ibuprofen-loaded pectin-based aerogels were released at 90.0 %, 84.0 %, and 75.5 %, respectively. The release of diclofenac sodium-loaded, pectin-based aerogels was at 88.4 %. The Korsmeyer–Peppas model was fitted for both ibuprofen and diclofenac sodium, indicating the release is mainly driven by diffusion.

Carbon Nanofibrous Aerogels Derived from Electrospun Polyimide for Multifunctional Piezoresistive Sensors.

The fabrication of carbon aerogels with ultralow density, high electrical conductivity, and ultraelasticity still remains substantial challenges. This study utilizes electrospun polyimide aerogel as the source to fabricate flexible carbon nanofibrous aerogel (PI-CNA) capable of multifunctional applications. The lightweight PI-CNA based piezoresistive sensor shows a wide linear range (0-217 kPa), rapid response/recovery time, and fatigue resistance (12,000 cycles). More importantly, the superior pressure sensing enables the PI-CNA for all-range healthcare sensing, including pulse monitoring, physiological activity detection, speech recognition, and gait recognition. Moreover, the EMI SE and the A coefficient of the PI-CNA reach 45 dB and 0.62, respectively, indicating the outstanding absorption dominated EMI shielding effects due to the multiple reflections and absorption. Furthermore, PI-CNA exhibits satisfying Joule heating performance up to 120 °C with rapid response time (10-30 s) under low supply voltages (1.5-5 V) and possesses sufficient heating reliability and repeatability in long-term repeated heating/cooling cycles. The fabricated PI-CNA shows significant potential applications in wearable technologies, energy conversion, electronic skin, and artificial intelligence.

Eco-friendly fabrication of aerogels from cigarette butts for removal of oil spill and cationic dye in wastewater

Eco-friendly fabrication of aerogels from cigarette butts for removal of oil spill and cationic dye in wastewater

Investigation of Gelation Techniques for the Fabrication of Cellulose Aerogels.

Because of the pronounced degradation of the environment, there has been an escalated demand for the fabrication of eco-friendly and highly efficient products derived from renewable sources. Cellulose aerogels have attracted significant interest attributable to their structural characteristics coupled with biodegradability and biocompatibility. The features of the molecular structure of cellulose allow for the use of various methods in the production of gels. For instance, the presence of hydroxyl groups on the cellulose surface allows for chemical crosslinking via etherification reactions. On the other hand, cellulose gel can be procured by modulating the solvent power of the solvent. In this study, we investigate the impact of the gelation methodology on the structural attributes of aerogels. We present methodologies for aerogel synthesis employing three distinct gelation techniques: chemical crosslinking, cryotropic gelation, and CO2-induced gelation. The outcomes encompass data derived from helium pycnometry, Fourier-transform infrared spectroscopy, nitrogen porosimetry, and scanning electron microscopy. The resultant specimens exhibited a mesoporous fibrous structure. It was discerned that specimens generated through cryotropic gelation and CO2-induced gelation manifested higher porosity (93-95%) and specific surface areas (199-413 m2/g) in contrast to those produced via chemical crosslinking (porosity 72-95% and specific surface area 25-133 m2/g). Hence, this research underscores the feasibility of producing cellulose-based aerogels with enhanced characteristics, circumventing the necessity of employing toxic cross-linking agents. The process of gel formation through chemical crosslinking enables the creation of gels with enhanced mechanical properties and a more resilient structure. Two alternative methodologies prove particularly advantageous in applications necessitating biocompatibility and high porosity. Notably, CO2-induced gelation has not been hitherto addressed in the literature as a means to produce cellulose gels. The distinctive feature of this approach resides in the ability to combine the stages of obtaining an aerogel in one apparatus.

High-speed and scalable combustion fabrication of ultralight carbon nanotube aerogels below air density

In this study, we introduce a fast, scalable method to fabricate ultralight carbon nanotube (CNT) aerogels with a bulk density (ρ) lower than air, using a combustion process. Typical fabrication methods for ultralight nanocarbon aerogels (ρ ≤ 1.0 mg cm−3) often involve intricate steps, such as high-temperature annealing and thermal reduction. These processes are time-consuming and pose scalability challenges. Here, we propose a high-speed fabrication process for ultralight CNT aerogels by combusting cellulose nanofibers (CNF) as a sacrificial template. The combustion process for CNT/CNF composite aerogels in an open environment takes only a few seconds, and the fabricated CNT aerogels with a lower-than-air density (ρ ≥ 0.48 mg cm−3) have high light absorption and good thermal and mechanical stability. We further illustrate the capability of these ultralight CNT aerogels to achieve levitation upon heating like a hot air balloon. Ultralight CNT aerogels capable of levitation by heating, fabricated by our fast and scalable method, hold the potential to replace traditional motor-driven unmanned aerial vehicles and conventional stratospheric platforms, such as high-altitude balloons, with sunlight-driven materials.

"Rigid-Flexible" Anisotropic Biomass-Derived Aerogels with Superior Mechanical Properties for Oil Recovery and Thermal Insulation.

Aerogels with low density, high mechanical strength, and excellent elasticity have a wide potential for applications in wastewater treatment, thermal management, and sensors. However, the fabrication of such aerogels from biomass materials required complex preparation processes. Herein, a sustainable and facile strategy was reported to construct lignin/cellulose aerogels (LCMA) with three-dimensional interconnected structures by introducing homologous lignin with a polyphenyl propane structure as a structural enhancer through a top-down directional freezing approach, prompting a 2036% enhancement in compressive modulus and an 8-12-fold increase in oil absorption capacity. In addition, the hydrophobic aerogels with superelasticity were achieved by combining the aligned polygon-like structure and flexible silane chains, which exhibited remarkable compressional fatigue resistance and superhydrophobicity (WCA = 168°). Attributed to its unique pore design and surface morphology control, the prepared aerogel exhibited excellent performance in immiscible oil-water separation and water-in-oil emulsion separation. Due to the ultra-low density (8.3 mg·cm-3) as well as high porosity (98.87%), the obtained aerogel showed a low thermal conductivity (0.02565 ± 0.0024 W·m-1·K-1), demonstrating a potential in insulation applications. The synthetic strategy and sustainability concept presented in this work could provide guidance for the preparation of advanced biomass-based aerogels with unique properties for a wide range of applications.

Fabrication of composite aerogels from waste tires and fly ash for thermal and acoustic insulation applications

Recently, extensive research has been conducted on composite aerogel materials fabricated using industrial waste sources. These aerogels can not only help solve the most challenging environmental issues brought on by waste streams, but are also materials with excellent properties for thermal and acoustic insulation applications. This study, therefore, focuses on synthesizing composite aerogel using waste tire rubber powder and fly ash attained from power plants in a simple and environmentally friendly manner. The results show that the composite aerogel has a very low density (0.055- 0.079 g/cm3), a porosity of up to 96.57%, low thermal conductivity (0.022-0.039 W/m.K), an adequate noise reduction number (NRC) (0.41 at 250-4000 Hz) and high compressive Young’s modulus (120.5 kPa). These properties show the high potential of the material for thermal and sound insulation of buildings. Especially in the context of utilizing a reasonably priced source of waste material.

Synthesis and characterization of UiO-66-NH2 incorporated PVA/cellulose nanofibers composite aerogel for enhanced oil–water separation and formaldehyde adsorption

The fabrication of high-hydrophobic aerogels represents an auspicious trajectory for economical and eco-friendly methodologies pertinent to oil–water separation and indoor volatile gas sorption. Notwithstanding, antecedent endeavors have engendered aerogels that markedly fall short of the requisite efficacy and mechanical resilience. Within the scope of the present investigation, we employ a novel composite aerogel, amalgamating a metal–organic framework, UiO-66-NH2, within a cellulose-predicated aerogel (CPU/A). This notable integration substantially contracts pore dimensions, augments the specific surface area and pore volume, and markedly bolsters the mechanical attributes of the pristine CP/A aerogel. The composite aerogel, specifically the CPU/A-0.10 variant comprising 10 wt% UiO-66-NH2, manifests superior oil–water separation performance and formaldehyde gas sorption capacity. This is characterized by a substantial enhancement in oil wettability and an appreciably elevated formaldehyde sorption capacity, relative to extant aerogel technologies. The superlative performance of the composite aerogel is maintained across multiple cycles, with considerable stability discerned over 10 oil–water separation cycles and 5 formaldehyde gas adsorption cycles. These findings underscore the potential of this composite aerogel as an efficacious, sustainable solution for large-scale oil spill remediation and indoor volatile gas sorption.

Fabrication, Performance, and Potential Applications of MXene Composite Aerogels.

Aerogel, known as one of the remarkable materials in the 21st century, possesses exceptional characteristics such as high specific surface area, porosity, and elasticity, making it suitable for a diverse range of applications. In recent years, MXene-based aerogels and MXene composite aerogels as functional materials have solved some limitations of traditional aerogels, such as improving the electrical conductivity of biomass and silicon aerogels, further improving the energy storage capacity of carbon aerogels, enhancing polymer-based aerogels, etc. Consequently, extensive research efforts have been dedicated to investigating MXene-based aerogels, positioning them at the forefront of material science studies. This paper provides a comprehensive review of recent advancements in the preparation, properties, and applications of MXene-based composite aerogels. The primary construction strategies employed (including direct synthesis from MXene dispersions and incorporation of MXene within existing substrates) for fabricating MXene-based aerogels are summarized. Furthermore, the desirable properties (including their applications in electrochemistry, electromagnetic shielding, sensing, and adsorption) of MXene composite aerogels are highlighted. This paper delves into a detailed discussion on the fundamental properties of composite aerogel systems, elucidating the intricate structure-property relationships. Finally, an outlook is provided on the opportunities and challenges for the mass production and functional applications of MXene composite aerogels in the field of material engineering.

Surface fabrication of silica aerogels from inorganic precursor achieving elastic and superhydrophobic sponges for oil-water separation

Some challenges exist in oil-water separation materials, including complex synthesis, high preparation costs, and weak recovery. Herein, the elastic and superhydrophobic silica aerogels/polyurethane sponges (SA/PUS) were prepared by fabricating silica aerogels (SA) on the skeleton of the cheap polyurethane sponges (PUS), through a simple dipping and sol-gel method under ambient pressure drying procedure. Importantly, boosted by the inorganic silicon precursors, the dense and rough coating by the functionalized SA on the surface was realized under environmentally friendly modification and adhesive-free, which contributed to the superhydrophobicity of the SA/PUS. The splendid thermal stability allowed the SA/PUS to maintain a hydrophobic property at high temperatures (over the flash point of the oil in this work). The excellent adsorption performance was confirmed on both oil/water mixture (11 times own weight) and oil-in-water emulsion (separation efficiency up to 98.78%). Moreover, the elastic SA/PUS could recover from large-scale deformations owing to the combination with the PUS with a three-dimensional skeleton, which improved the mechanical strength and overcome the limitation of the brittle SA. The recovery efficiency of the adsorbed oil from oil/water mixture was 92.70% and nearly no decline in reusing by simple mechanical squeezing. Such excellent performance was also demonstrated in oil-in-water emulsion. Advantages (superhydrophobic and lipophilic, elastic, and thermal stability, etc.) of the SA/PUS, which were prepared by simple synthesis, bring application potential for treating automobile maintenance sewages and expanded applications, including separation and recovery of oil from oily wastewater circularly and uptake of high-value-added hydrophobic molecules in biomass or other processes.

Aerogel-Based Biomaterials for Biomedical Applications: From Fabrication Methods to Disease-Targeting Applications.

Aerogel-based biomaterials are increasingly being considered for biomedical applications due to their unique properties such as high porosity, hierarchical porous network, and large specific pore surface area. Depending on the pore size of the aerogel, biological effects such as cell adhesion, fluid absorption, oxygen permeability, and metabolite exchange can be altered. Based on the diverse potential of aerogels in biomedical applications, this paper provides a comprehensive review of fabrication processes including sol-gel, aging, drying, and self-assembly along with the materials that can be used to form aerogels. In addition to the technology utilizing aerogel itself, it also provides insight into the applicability of aerogel based on additive manufacturing technology. To this end, how microfluidic-based technologies and 3D printing can be combined with aerogel-based materials for biomedical applications is discussed. Furthermore, previously reported examples of aerogels for regenerative medicine and biomedical applications are thoroughly reviewed. A wide range of applications with aerogels including wound healing, drug delivery, tissue engineering, and diagnostics are demonstrated. Finally, the prospects for aerogel-based biomedical applications are presented. The understanding of the fabrication, modification, and applicability of aerogels through this study is expected to shed light on the biomedical utilization of aerogels.

Application of Nanocellulose-Based Aerogels in Bone Tissue Engineering: Current Trends and Outlooks.

The complex or compromised bone defects caused by osteomyelitis, malignant tumors, metastatic tumors, skeletal abnormalities, and systemic diseases are difficult to be self-repaired, leading to a non-union fracture. With the increasing demands of bone transplantation, more and more attention has been paid to artificial bone substitutes. As biopolymer-based aerogel materials, nanocellulose aerogels have been widely utilized in bone tissue engineering. More importantly, nanocellulose aerogels not only mimic the structure of the extracellular matrix but could also deliver drugs and bioactive molecules to promote tissue healing and growth. Here, we reviewed the most recent literature about nanocellulose-based aerogels, summarized the preparation, modification, composite fabrication, and applications of nanocellulose-based aerogels in bone tissue engineering, as well as giving special focus to the current limitations and future opportunities of nanocellulose aerogels for bone tissue engineering.