Aerogel Fibers Research Articles

Ultra‐High Radial Elastic Aerogel Fibers for Thermal Insulation Textile

AbstractWhen nanoporous aerogels with excellent thermal insulation performance are processed into 1D fibers, they have great potential for application in the field of personal thermal management. However, coping with the impact of external forces, especially radial extrusion, and maintaining the macro morphology and microstructure of aerogels during use are remaining issues. To address these challenges, this study proposes a method that uses ultrafine and ultra‐highly entangled bacterial cellulose nanofibers as the basis to achieve high radial elasticity by forming an isomorphic coating of rigid silica on the soft gel skeleton of aerogel fibers. The obtained aerogel fibers can achieve an elastic recovery of 88% over 50 compression cycles under 90% strain, and they can be knotted, woven into textiles, and are washable. This strategy improves the radial compression resistance of aerogel fibers, providing rich possibilities for the development of aerogel fibers with excellent mechanical properties.

Bamboo-derived aerogel with atomically dispersed Co as a high-performance bifunctional electrocatalyst for durable zinc-air batteries

The development of highly efficient and durable bifunctional electrocatalysts is crucial for rechargeable zinc-air batteries, which have garnered significant attention as a promising sustainable energy storage technology. Herein, a novel Co-N-C-1050 catalyst is synthesized using a high-temperature gas transport method, where high purity cobalt powder and bamboo biomass aerogel are treated with ammonia gas at 1050 °C. The resulting catalyst exhibits a 3D interconnected porous network composed of dense carbon fibers, which atomically dispersed Co, N, and C elements are uniformly distributed. The synergistic integration of highly active Co single atoms and N-doped 3D carbon fiber aerogel enables Co-N-C-1050 to demonstrate excellent bifunctional electrocatalytic performance for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER), comparable to commercial Pt/C and RuO2 catalysts. This catalyst has a half-wave potential of 0.842 V for ORR and a potential of 1.472 V at 10 mA cm−2 for OER, outperforming N-C-1050 and benchmark catalysts. A zinc-air battery is driven by Co-N-C-1050 achieves a high power density of 135 mW/cm2 and exceptional stability over 138 h of charge/discharge cycling, surpassing the higher-cost Pt/C + RuO2 catalyst. This biomass aerogel based single-site Co-N-C catalyst offers a promising approach for developing high-efficiency and long-cycle-life zinc-air batteries.

Coaxial porous SiBCN/SiCN ceramic fiber aerogels with reduced shrinkage and low thermal conductivity

Coaxial porous SiBCN/SiCN ceramic fiber aerogels with reduced shrinkage and low thermal conductivity

Upcycling Industrial Biomass Wastes Into Aerogels Using Zinc Chloride Salt Hydrates

AbstractEnd‐of‐life paper products, including food packages and rejected fibers from the paper industry, are unrecyclable biomass wastes and thus generally landfilled or incinerated. One of the major obstacles to their recycling is the existence of impurities besides cellulose fiber in the biomass wastes. In this study, a fabrication method is investigated to upcycle biomass wastes directly into high‐performance aerogels without separation of impurities. Surprisingly, this study observes that residual impurities participate in cross‐linking reactions for the aerogel formation. In this study, zinc chloride salt hydrate is applied to convert biomass wastes to aerogel via a dissolution‐regeneration process. The fabricated aerogels exhibited high water absorption capacity (15 times its weight), as well as comparable mechanical strength and thermal insulation performance to the reported cellulose aerogels. In addition, the impurities (i.e., calcium‐based inorganic salt) assisted in the cross‐linking of the cellulose network for the aerogel formation. The scanning electron microscopy (SEM) image of the aerogel generated from the rejected fibers showed a honeycomb inner structure. The rejected fiber aerogels also demonstrated a high compressive modulus of 51 MPa and a low thermal conductivity of 0.029 W m−1 K−1. The results for water absorption and thermal insulation suggest excellent potential across various application domains.

Investigation of the coloration and mechanical properties of polymer cross-linked para-aramid aerogel fibers with blue color derived from light scattering

Investigation of the coloration and mechanical properties of polymer cross-linked para-aramid aerogel fibers with blue color derived from light scattering

Bio-Templated Aerogel Fibers: Heterogeneous Spinodal Architecting and In Situ Fibrillation of Thermoplastic Polyurethane-Silica on Nanostructured Cellulose Nanofiber Scaffold for Enhanced Thermomechanical Performance.

This study addresses the inherent fragility and fractal limitations of traditional silica aerogels by developing a bio-templated aerogel fiber. Integrating cellulose nanofibers (CNFs), thermoplastic polyurethane (TPU), and silica aerogel (SA) in a dimethyl sulfoxide (DMSO) dispersion, a gel-spinning technique was employed to create aerogel fibers with superior thermomechanical performance. CNF also provided excellent rheological modification for successful spinnability, fast gelation, and fiber formation. The unique hierarchical structure of these fibers, formed through hot-stretching and surface modification, combined the superior mechanical strength and flexibility of TPU with the exceptional insulation properties of CNF and SA. The CNF network, encapsulated within the SA particles, formed a core-shell structure, axially aligned, that significantly enhances the thermal stability and mechanical performance of the fibers while maintaining a lightweight and porous architecture. Comprehensive morphological, thermal, and mechanical analyses were conducted to evaluate the properties of the developed aerogel fibers. Fourier transform infrared (FTIR) spectroscopy and nuclear magnetic resonance (NMR) spectroscopy verified the successful surface modification and grafting reactions on CNF, contributing to improved hydrophobicity and thermal insulation. Adjusting the CNF content allowed for tailoring of the thermomechanical characteristics, with a notable 294% increase in tensile strength from 5.3 to 15.6 MPa and an enhanced crystallization temperature from 106 to 119.97 °C. Furthermore, cyclic tensile and compression tests validated the durability and shape recovery capabilities of the aerogel fibers, making them promising candidates for high-performance applications in extreme environments. The thermal conductivity validated by experimental data further highlights the potential of CNF-based aerogel fibers as sustainable and multifunctional materials for advanced thermal insulation, mechanical reinforcement, and flexible structural applications.

Electric Field-Induced Ordered-Structural Aerogels Enable Superinsulation and Multifunctionality.

1D flexible fibers assembled 3D porous networked ceramic fiber aerogels (CFAs) are developed to overcome the brittleness of traditional ceramic particle aerogels. However, existing CFAs with disordered and quasi-ordered structures fail to balance the relationship between flexibility, robustness, and thermal insulation. Creating novel architectural CFAs with an excellent combination of performances has proven extremely challenging. In this paper, a novel strategy is adopted to fabricate porous mullite fibrous aerogels (MFAs) with ordered structures by combining fiber sedimentation and electric field-induced fiber alignment techniques. For the first time, electric field-induced alignment of ceramic fibers is utilized to prepare bulk aerogels on a large scale. The resulting MFAs exhibit ultra-low high-temperature thermal conductivity of 0.0830 W m-1 K-1 at 1000°C, anisotropic mechanical and sound absorption performances, and multifunctionality in terms of the combination of thermal insulation, sound absorption, and hydrophobicity. The successful synthesis of such fascinating materials may provide new insights into the design and development of multifunctional CFAs for various applications.

Polyimide Aerogel Fiber Bundles for Extreme Thermal Management Systems in Aerospace Applications.

Aerogel fibers are an emerging class of ultralightweight materials, which, compared to conventional bulk monolithic and aerogel films, provide better flexibility and extensibility. Despite the recent advancements in this field, due to their highly porous structure, their mechanical properties can be deteriorated. Inspired by the textile industry, we report the development of aerogel fiber bundles with twisted structures as a promising strategy to enhance the mechanical performance and practicality of aerogel fibers. Polyimide (PI) aerogel fibers were prepared via the sol-gel confined transition method. The fibers showed a unique nanostructured assembly with high specific surface area, excellent optical transparency, outstanding flexibility at diverse extreme conditions, self-extinguishing behavior, and superior thermal insulation performance. Using PI aerogel fibers as the backbone, aerogel fiber bundles in various configurations were designed and fabricated. A systematic study was performed to analyze the effect of design parameters on the mechanical performance of the bundles. Results revealed an optimal twist level for bundles, leading to a peak in mechanical properties across various bundle configurations. The observed improvement in mechanical properties was attributed to increased fiber-to-fiber binding strength, enhanced friction, and interlocking mechanism of fibers, underscoring the potential of the optimized twist level for enhancing the performance of aerogel fiber bundles. Overall, the development of aerogel fiber bundles holds great promise in revolutionizing the production of high-performance ultralightweight materials for thermal management applications.

Amine-impregnated elastic carbon nanofiber aerogel templated by bacterial cellulose for CO2 adsorption and separation

Carbon aerogel has become a promising electrode material for CO2 capture and capacitor due to its large specific surface area, well-developed pore structure, adjustable porosity and ultra-high specific power. However, most of the carbon-based materials suffer from poor mechanical properties, low recycling efficiency, and low adsorption capacity, making it difficult to be put into industrial applications on a large scale. Bacterial cellulose (BC) has an ultra-fine reticular structure, a modulus of elasticity that is several to more than ten times that of typical plant fibers, and high tensile strength. In this paper, BC was treated by unidirectional freeze-drying method, and the aerogels with ordered honeycomb pore structure were constructed by unidirectional growth of ice crystals, and the pyrolytic chemical properties of BC were adjusted by using (NH4)2SO4, which effectively prevented the shrinkage and deformation of materials during carbonization, and successfully prepared elastic nanocarbon fiber aerogels. At the same time, the introduction of (NH4)2SO4 made the material realize N doping in the carbonization process, providing more adsorption sites, which was conducive to the adsorption of CO2. Finally, the carbon fiber nanoaerogel was modified by TEPA to further improve its adsorption selectivity for CO2. The prepared elastic carbon nanofiber aerogel (CBCNT) has high CO2 adsorption performance and high selectivity, and its CO2 capture capacity is up to 4.88 mmol/g. At the same time, its capacitance also reached 246F/g.

Electrothermal Dual Activities of Elastic Fiber Aerogels for Sensing Diagnosis and Thermotherapy

Electrothermal Dual Activities of Elastic Fiber Aerogels for Sensing Diagnosis and Thermotherapy

Lightweight carbon fiber aerogel@hollow carbon/Co3O4 microsphere for broadband electromagnetic wave absorption in X and Ku bands

The increasing proliferation of modern communications, radar systems, and military equipment operating in the X and Ku bands (8–18 GHz) has exacerbated the issue of electromagnetic wave (EMW) pollution, highlighting the urgent need for lightweight, broadband EMW-absorbing materials. In this paper, the lightweight carbon fiber aerogel@hollow carbon/Co3O4 microsphere (CFA@H–C/Co3O4) were composed by ZIF-67 derived hollow carbon/Co3O4 microsphere and bamboo cellulose fiber derived carbon fiber aerogels and constructed by in-situ chemical deposition, dopamine treatment and pyrolysis. Carbon fiber aerogels form a lightweight three-dimensional (3D) interconnected conductive network, which expands the multiple reflection and absorption paths of EMW and increases the dielectric loss. The hollow carbon/Co3O4 microsphere inhibits the collapse of the structure by forming a polydopamine shell through the self-polymerization effect of dopamine on the surface of ZIF-67 during pyrolysis, showing dipole polarization loss, interface polarization loss and magnetic loss, which plays an important role in improving EMW polarization loss and optimizing impedance matching. The minimum reflection loss (RLmin) of CFA@H–C/Co3O4 reaches −43.5 dB at frequency of 12.88 GHz with thickness of 3.0 mm and the effective absorption bandwidth (EAB) of CFA@H–C/Co3O4 reaches 7.84 GHz (10.08–17.92 GHz) with thickness of 3.0 mm, covering most of X and Ku bands at a low filling ratio of 15 wt%. The radar cross-section (RCS) value of CFA@H–C/Co3O4 is 22.68 dB m2 lower than the perfect electrical conductor (PEC). This study provides valuable insights into materials that can improve the absorption bandwidth of electromagnetic waves in the X and KU bands.

BN fiber aerogels with high solar reflectivity and thermal insulation for green buildings

There exists more than one-third of the stock of buildings that do not meet energy-saving building standards, so there is an urgent need for breakthroughs in the field of green buildings. Herein, we successfully prepared boron nitride (BN) fiber aerogels by sol-gel, freeze-drying and high-temperature pyrolysis. When the molar ratio of C3N6H6 to H3BO3 was 1:2 and the roasting temperature was 1000 °C, the BN fiber aerogel was produced with high specific surface area (257.690 m2/g) and high porosity (99 %). BN fiber aerogels, with their low thermal conductivity (0.043 W/(m·K)) and stable mechanical properties (no change after 45 cycles at 30 % strain), offered possibilities for thermal insulation in green buildings. Its hydrophobic properties protect the wall from the natural environment. In particular, it had a solar reflectivity of 98.6 %, which exceeds most reflective coating materials, enabling the cooling of green construction on hot summer days. The high-temperature resistance of BN fiber aerogels could be applied in special environments such as blast furnace plants and thermoelectric power plants.

Mechanically Robust and Thermal Insulating Silica/Aramid Nanofiber Composite Aerogel Fibers with Dual Networks for Fire‐Resistant and Flexible Triboelectric Nanogenerators

Mechanically Robust and Thermal Insulating Silica/Aramid Nanofiber Composite Aerogel Fibers with Dual Networks for Fire‐Resistant and Flexible Triboelectric Nanogenerators

Aerogel Fibers Made via Generic Sol‐Gel Centrifugal Spinning Strategy Enable Dynamic Removal of Volatile Organic Compounds From High‐Flux Gas

AbstractAerogels with ultrahigh porosity and large specific surface area have demonstrated great potential for capturing volatile organic compounds (VOCs). Especially, aerogel fiber aggregates with macropores formed by overlapping aerogel fibers and mesopores in the aerogel fibers might realize fast sorption kinetics and high sorption capacity simultaneously. However, how to develop fast fabrication and large‐scale production of aerogel fibers remains a challenge. Herein, a generic sol‐gel centrifugal spinning (SCS) strategy with a spinning rate capable of reaching 700 m min−1 is developed for producing aerogel fibers. The representative SCS aerogel fiber made from aramid nanofiber (ANF) dispersion exhibits a large specific surface area (313 m2 g−1) and high tensile strength (12.48 MPa). The SCS strategy is further applied to fabricate various kinds of aerogel fibers, including sodium alginate, cellulose, and chitosan. The ANF aerogel fiber aggregates exhibit superior VOC adsorption capacity of 438.0 mg g−1 under an ultrafast gas flux of 3.8 × 104 L m−2 h−1, which also has satisfactory cyclic stability. This work not only develops a powerful and generic strategy for fabricating aerogel fibers in large scale, but also provides inspiration for applying these SCS aerogel fibers in dynamic removal of VOCs and other environmental protection fields.

Metal-organic framework incorporated polybenzimidazole aerogel fibers with dual protections for thermal hazards and chemical warfare agents

Aerogel fibers possess the flexibility of fiber materials and the high porosity and low thermal conductivity of aerogel materials, which hold great promising for applications in thermal insulation and personal protection. However, the inferior mechanical performance and the lack of functionality have impeded the wider applications of these fascinating materials. Herein, we report a novel kind of MOF/polybenzimidazole composite aerogel fibers (CAFs) with both physical and chemical protection functions. The CAFs are fabricated by an oxidation induced sol–gel transition spinning method that utilized the transition of labile imidazole/Co2+ coordination bonds to stable imidazole/Co3+ coordination bonds upon oxidation. The incorporation of MOF has obviously improved the strength and ductility of CAFs due to the good interfacial interactions with matrix and increased crosslinking among polymer chains. The CAFs maintain the high thermal stability and flame retardancy of polybenzimidazole matrix, while the increased porosity and surface area with the addition of MOF have lowered the thermal conductivity and improved the thermal insulation performance of CAFs. The uniform porous skeleton also facilitates the access of chemical warfare agents (CWAs) to MOF inside the fiber. The catalytic experiments show that the CAFs have better degradation effect on CWAs than pure MOF powder, dense composite fiber, and MOF coated fiber. This work is expected to provide an efficient strategy for strong and multifunctional aerogel fibers.

Curvature-ordered biomimetic helical ceramic composite fiber aerogel with shrinkage resistance, thermal insulation properties, and mechanical properties

Ceramic aerogel with high porosity and low thermal conduction was widely used in the field of thermal insulation. However, shrinkage and structural damage were produced by the ceramic precursors during pyrolysis. The shrinkage and mechanical properties of ceramic aerogels required to be improved. Herein, inspired by spiral grass and passionflower, curvature-ordered ceramic fiber aerogels were prepared by electrostatic spinning combined with polymer-derived ceramics (PDCs) route. Shrinkage resistance properties, thermal insulation properties, and mechanical properties of ceramic fiber aerogels were investigated. The shrinkage resistance property of aerogels was improved by the tensile deformation of helical fibers during pyrolysis. The path of heat transfer was extended through the helical fibers and heat conduction was reduced. The gas was confined in a porous network formed by helical fibers that lapped over each other, and thermal convection was minimized. Thermal radiation was attenuated due to reflection and scattering at the core-shell interface of the helical fibers. The mechanical properties of the aerogel were enhanced by the helical structure of the fibers and the stress diffusion mechanism. The tensile and compressive properties of the spiral ceramic aerogel were improved through the curvature structure by about 6 MPa and 3 MPa, respectively. The results showed that the helical ceramic composite fiber aerogel with ordered curvature exhibited shrinkage resistance, thermal insulation, and mechanical properties.

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.

Robust and ultra-sensitive self-powered fire warning sensor based on polyimide thermoelectric fibers for temperature sensing and intelligent fire safety monitoring

Fire warning sensors is crucial to effectively prevent fire accidents in a variety of modes and meet the needs of the connected age. Nevertheless, there is still a formidable challenge in fabricating self-powered fire warning sensors that are flexible and can be integrated in combustible materials. In this work, flexible high-fireproof polyimide (PI)/hydroxyapatite (HAP)/Ag2Se composite aerogel fiber (PHA-AF) was fabricated by specific wet spinning technology. The extraordinary thermoelectric effect of Ag2Se enabled PHA-AF to achieve precise temperature sensing over a wide temperature range of 100 °C–500 °C. Simultaneously, the PHA-AF-based fire alarm sensor could trigger a fire alarm system in 1.9 s and respond continuously for 14 s under flame attack, while generating output voltage of up to 5.9 mV in self-powered mode. Notably, PI as a flame-retardant material could be formed the 3D networks with HAP, as well as the skeleton support effect provided by Ag2Se nanorods enabled PHA-AF based fire alarm sensors with superior breaking tenacity (2.9 MPa), strong heat stability (maximum weight loss rate at 550 °C) and flame retardancy (LOI = 35.8 %), further highlighting its authenticity, repeatability, and reliability in fire. This work offers potential for the preparation of fiber-based self-powered early fire alarm sensors for long-term continuous using in harsh fire environment.

Topological Polymer Networks-Enabled Mechanically Strong Polyamide-Imide Aerogel Fibers for Thermal Insulation in Harsh Environments.

Aerogel fibers have sparked substantial interest as attractive candidates for thermal insulation materials. Developing aerogel fibers with the desired porous structure, good knittability, flame retardancy, and high- and low-temperature resistance is of great significance for practical applications; however, that is very challenging, especially by using an efficient method. Herein, mechanically strong and flexible aerogel fibers with remarkable thermal insulation performance are reported, which are achieved by constructing stiff-soft topological polymer networks and a multilevel hollow porous structure. The combination of polyamide-imide (PAI) with stiff chains and polyurethane (PU) with soft chains is first found to be able to form a topological entanglement architecture. More importantly, multilevel hollow pores can be constructed synchronously through just a one-step and green wet-spinning process. The resultant PAI/PU@340 aerogel fibers show an ultrahigh breaking strength of 94.5 MPa and superelastic property with a breaking strain of 20%. Furthermore, they can be knitted into fabrics with a low thermal conductivity of 25 mW/(m·K) and exhibit attractive thermal insulation property under extremely high (300 °C) and low temperatures (-191 °C), implying them as promising candidates for next-generation thermal insulation materials.

Strong, Tough, and Recyclable Aramid Aerogel Fibers with Homogeneous Nanoscale Structures for High-Temperature Thermal Insulation Applications

Strong, Tough, and Recyclable Aramid Aerogel Fibers with Homogeneous Nanoscale Structures for High-Temperature Thermal Insulation Applications