Nanomaterials in Advanced, High-Performance Aerogel Composites: A Review (original) (raw)
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Aerogels are unique and extremely porous substances with fascinating characteristics such as ultra-low density, extraordinary surface area, and excellent thermal insulation capabilities. Due to their exceptional features, aerogels have attracted significant interest from various fields, including energy, environment, aerospace, and biomedical engineering. This review paper presents an overview of the trailblazing research on aerogels, aiming at their preparation, characterization, and applications. Various methods of aerogel synthesis, such as sol-gel, supercritical drying, are discussed. Additionally, recent progress in the characterization of aerogel structures, including their morphology, porosity, and thermal properties, are extensively reviewed. Finally, aerogel's utilizations in numerous disciplines, for instance, energy storage, thermal insulation, catalysis, environmental remedy, and biomedical applications, are summarized. This review paper provides a comprehensive understanding of aerogels and their prospective uses in diverse fields, highlighting their unique properties for future research and development.
Aerogels for Biomedical, Energy and Sensing Applications
Gels, 2021
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 synthes...
An Opinion Paper on Aerogels for Biomedical and Environmental Applications
Molecules
Aerogels are a special class of nanostructured materials with very high porosity and tunable physicochemical properties. Although a few types of aerogels have already reached the market in construction materials, textiles and aerospace engineering, the full potential of aerogels is still to be assessed for other technology sectors. Based on current efforts to address the material supply chain by a circular economy approach and longevity as well as quality of life with biotechnological methods, environmental and life science applications are two emerging market opportunities where the use of aerogels needs to be further explored and evaluated in a multidisciplinary approach. In this opinion paper, the relevance of the topic is put into context and the corresponding current research efforts on aerogel technology are outlined. Furthermore, key challenges to be solved in order to create materials by design, reproducible process technology and society-centered solutions specifically for ...
Nanostructural engineering of organic aerogels
1995
Aerogels are a special class of open-cell foams with an ultrafine cell/pore size (<50 nm), high surface area (400-1100 M{sup 2}/g), and a solid matrix composed of interconnected colloidal-like particles or fibers with characteristic diameters of 10 nm. This paper examines the correlation between nanostructure and thermal conductivity in a series of resorcinol-formaldehyde (RF) aerogels prepared under different synthetic conditions.
Advanced Engineering and Research of aeroGels for Environment and Life Sciences (AERoGELS)
2019
AERoGELS COST Action intends to bring together the knowledge on research and technology of aerogels at the European level from academia, industry and regulatory experts. Aerogels are a special class of mesoporous materials with very high porosity and tunable physicochemical properties. Although some types of aerogels have already reached the market in construction materials and aerospace engineering, the full potential of aerogels are still to be assessed for other sectors. In this Action, the use of aerogels specifically for environmental and life sciences applications will be explored in a multidisciplinary approach to tackle two of the current main European challenges: circular economy and active ageing. The scope of the Action is to advance the state-of-the art on the topic by joining the knowledge and efforts of the most renowned experts on cutting-edge aerogel technology, on advanced characterization of materials as well as on biomedical and environmental research. Aerogels wi...
Mechanical behaviour of nano composite aerogels
Journal of Sol-gel Science and Technology, 2011
In order to improve the mechanical properties of silica aerogels, we propose the synthesis of nano composite aerogels. Silica particles (20â100 nm) are added in the monomer solution, just before gelling and supercritical drying. The silica particles addition increases the mechanical properties, but also affects the aggregation process, the aerogel structure and the pore sizes. We discuss the different parameters which infer in the mechanical behaviour of silica aerogel such as: brittle behaviour, load bearing fraction of solid (pore volume), internal stresses (shrinkage), size and distribution of flaws, subcritical flaws propagation (chemical susceptibility). With silica particles addition, the mechanical properties rapidly increase, stiffening and strengthening the structure by a factor 4â8. Moreover, the mechanical strength distribution and the Weibull modulus characterizing the statistical nature of flaws size in brittle materials show a more homogeneous strength distribution. The composite structure is made of two imbricate networks, the polymeric silica and the particles silica networks. Ultra Small Angle X-ray Scattering experiments show that besides the fractal network usually built up by the organosiloxane, the silica particles is forming another fractal structure at a higher scale. The fractal structure could be related to the low Weibull parameter characteristic of a large flaws size distribution, pores being the critical flaws.
Journal of Physics: Conference Series, 2010
Aerogels are highly porous nanostructured materials with excellent thermal insulation properties. The possibility to add additional functionto functionalize the aerogels, especially to produce photovoltaic electricity, will make them an excellent candidate for energy-efficient building. Going in the direction of this midterm goal we start with the investigation of the properties of the readily available silica aerogels. Atomic Force Microscopy reveals large areas with submicrometer roughness, which allows reliable nanoidentation measurements. The average hardness was measured to be 2,2 MPa and the Young's modulus was 11 MPa, values typical for low density elastic silica aerogels. Electrochemical Impedance Spectroscopy, measured in ambient air, shows typical capacitive behaviour and the aerogel is best modelled by serially connected resistance of 37 kâĤ and capacitor of 170 pF. The conductivity is interpreted in terms of proton migration, strongly dependant on air humidity.
Synthetic Polymer Aerogels in Particulate Form
Materials, 2019
Aerogels have been defined as solid colloidal or polymeric networks of nanoparticles that are expanded throughout their entire volume by a gas. They have high surface areas, low thermal conductivities, low dielectric constants, and high acoustic attenuation, all of which are very attractive properties for applications that range from thermal and acoustic insulation to dielectrics to drug delivery. However, one of the most important impediments to that potential has been that most efforts have been concentrated on monolithic aerogels, which are prone to defects and their production requires long and costly processing. An alternative approach is to consider manufacturing aerogels in particulate form. Recognizing that need, the European Commission funded "NanoHybrids", a 3.5 years project under the Horizon 2020 framework with 12 industrial and academic partners aiming at aerogel particles from bio-and synthetic polymers. Biopolymer aerogels in particulate form have been reviewed recently. This mini-review focuses on the emerging field of particulate aerogels from synthetic polymers. That category includes mostly polyurea aerogels, but also some isolated cases of polyimide and phenolic resin aerogels. Particulate aerogels covered include powders, micro granules and spherical millimeter-size beads. For the benefit of the reader, in addition to the literature, some new results from our laboratory concerning polyurea particle aerogels are also included.
Nanostructure and Bioactivity of Hybrid Aerogels
Chemistry of Materials, 2009
Hybrid sono-aerogels in the CaO-SiO 2 -poly(dimethyl siloxane) (PDMS) system with low density and high surface area and pore volume were investigated to be used as biomaterials. Their in vitro bioactivity was monitored by soaking in a simulated body fluid (SBF). All the aerogels exhibited similar wetting and dissolution properties, but only the aerogel of composition 20 wt % PDMS-20 wt % CaO (S20Ca20) exhibited a bioactive response in SBF. To investigate the relationship between the different in vitro behaviours and the hybrids nanostructure, samples were studied by high-resolution transmission electron microscopy (HRTEM). All the aerogels showed similar basic microstructural features exhibiting amorphous Ca-free areas characterized by Si-O-Si distances of 0.23 nm. However, crystallized nanodomains containing calcium were also detected in S20Ca20. These domains, identified as pseudowollastonite and other Ca-Si-O phases, could explain the bioactive response of this material. Bioactivity and good textural and mechanical properties turn S20Ca20 aerogel into a candidate as biomaterial.
Inorganic Hollow Nanotube Aerogels by Atomic Layer Deposition onto Native Nanocellulose Templates
ACS Nano, 2011
ne-dimensional nanostructures with lateral dimensions below 100 nm, including nanowires and nanotubes, are a technologically important class of materials with unique thermal, electronic, optical, and mechanical properties, and they are feasible in applications as nanoscale building blocks for functional materials and devices. 1 Inorganic nanowires, for example, have spurred research toward single-molecule detection, energy harvesting, nanoelectromechanical systems, and detection of neural signals. 2 Inorganic nanotubes have been pursued in optoelectronics, sensors, drug release, and fluid manipulation. 3 During recent years, many routes toward hollow inorganic nano-objects have been demonstrated, including templating on nanoporous membranes or nanofibers, for example, coating anodic alumina membranes by various methods, 4-8 directly anodizing titanium dioxide films, 9 coating electrospun fibers, 10,11 and coating block copolymer templates with inorganics. 12 In this context, also aerogels could be particularly useful as facile highly porous network-like solid templates for inorganic nanotubes. Highly porous solid materials, called aerogels, were first discovered in the 1930s, 13 and although silica aerogels were commercially produced already in the 1940s, 14 it was not until late 20th century when a more broad range of applications was introduced. 15,16 Nowadays several types of aerogels are made by sol-gel chemistry. In addition to silica, aerogels can be made from several different materials, such as polymers (including cellulose), which can then in turn be pyrolyzed to carbon aerogels. 15-21 Also metals and metal oxides, such as aluminum oxide and zinc oxide, 22,23 have been used to form aerogels. Cellulose is an interesting sustainable and natural polymer. Native cellulose forms a hierarchically ordered material, where the individual cellulose polymer chains first crystallize into nanofibrils of ca. 3-15 nm diameter, which then pack into larger fibers of several tens of nanometers, 24 and finally into macroscopic fibers of micrometer dimensions. The native nanofibrils can be cleaved by several ways to form nanocellulose hydrogels. 25-29 Usually the material is called nanofibrillated cellulose (NFC) or alternatively microfibrillated cellulose (MFC). While NFC is interesting in itself, it is also attractive as a biological template for functionalities. Cellulose hydrogels can be dried to form percolating networks, that is, aerogels, and