Aerogels: understanding the lightest materials in the world

Advanced materials shape the modern world with an unceasing quest for lightness and performance. Among them, aerogels hold a remarkable place, representing a fascinating paradox: a solid almost as light as air, endowed with extreme porosity and excellent thermal insulation capabilities. Initially developed in the 1930s, these nanostructured materials now reveal revolutionary potential across numerous industrial sectors. Whether in eco-friendly construction, space flights, or cutting-edge technologies, aerogels combine materials innovation and scientific advancements to push the boundaries of materials science.

This technological feat relies on a unique microstructure, giving these lightweight materials a low density and exceptional properties. Their ability to almost entirely stop conduction, convection, and thermal radiation makes aerogels one of the best-known insulators. Their composition is predominantly gaseous, often based on silica, which further grants them extreme lightness, even surprising materials experts. By 2025, innovations in the manufacturing and use of these nanostructures have paved the way for diverse industrial applications, making aerogel an innovative response to today’s challenges of sustainable development and energy performance.

The growing interest in these ultra-light materials also touches on energy, pharmaceuticals, and even environmental treatment, illustrating their versatility and the strategic importance of understanding their characteristics and functioning. Simultaneously solid and almost ethereal, aerogel has emerged today as a symbol of scientific ingenuity at the heart of future technologies.

In brief:

• Aerogels: solids composed of up to 99.8% air, offering ultralight density and unmatched thermal insulation capabilities.
• Nanostructures: their porous microstructure, made up of nanometric silica particles, is key to their mechanical and thermal properties.
• Industrial applications: these materials are revolutionizing building insulation, space protection, as well as the environmental and electrochemical sectors.
• Materials innovation: research today focuses on bio-sourced and hybrid aerogels to improve strength and reduce costs.
• Reduced thermal conductivity: due to a drastic interruption of heat transfer modes, aerogel positions itself as the most efficient insulator compared to traditional solutions.

Aerogels: nanoscale structures and exceptional properties of lightweight materials

Aerogels are characterized by their delicate and ultra-porous structure, a true three-dimensional architecture composed of branched chains in fractal shapes, where almost the entire volume is occupied by air. This network is made up of spherical silica particles or other materials, with sizes ranging from 2 to 5 nanometers. The porosity of these materials thus reaches pore dimensions of less than 100 nanometers, conferring exceptional lightness and an immense specific surface area.

This unique microstructure allows aerogel to have a density that can drop to as low as 0.16 mg/cm3, making it one of the lightest solid materials ever manufactured. Compared to conventional materials like glass wool or expanded polystyrene, aerogel is extremely fragile in its raw state, but its incredible porosity also enables it to support high loads relative to its own weight. For example, a sample weighing only 2 grams can support a brick weighing over 2.5 kilograms.

Beyond lightness, this structure plays a major role in the thermal insulation performance of aerogel. The combination of a weakly conductive solid like silica and a volume almost entirely occupied by air, a natural insulator, drastically limits thermal conduction. The complex network also prevents air convection inside the pores, as well as transmission by radiation, especially when dopants like carbon absorbing infrared are incorporated. This synergy of mechanisms gives aerogel a thermal conductivity coefficient up to three times lower than the best traditional insulators.

The development of these nanostructures is a technical challenge. Manufacturing requires precise control of synthesis conditions, particularly during supercritical drying, which delicately replaces the initial liquid of the gel with a gas, without collapsing the microstructure. Advances in microgravity have even shown that it is possible to obtain completely transparent aerogels, now being considered for applications in optics and window insulation. These characteristics demonstrate impressive versatility, fueling scientific and industrial ambitions.

Innovative manufacturing and synthesis of aerogels: complex processes and recent improvements

Manufacturing an aerogel requires a delicate and ingenious process, aimed at preserving the characteristic nanostructured structure during the transition from wet gel to ultra-light solid state. Initially, a hydrogel – a gel where the liquid phase is predominant – is obtained from chemical precursors like silica alkoxide. Through a controlled chemical reaction, silica forms a solid matrix while retaining a significant amount of water inside.

The core of the synthesis relies on supercritical drying, an advanced thermodynamic process that removes the contained liquid without destructive capillary tension. By surpassing the critical point of the fluid (typically the ethanol used as a solvent), the liquid phase is converted into a supercritical fluid, allowing its elimination without collapsing the porous network. This treatment occurs under pressures of 50 to 60 bars and at low temperature, over several days, ensuring the preservation of the intrinsic properties of the gel transformed into aerogel.

Research conducted up to 2025 has improved this process, making it more efficient and less energy-intensive. For instance, affordable methods utilizing partial dryings, or the introduction of new chemical techniques have effectively reduced production costs, which had long been viewed as a barrier to large-scale commercialization. This has opened the door to broader industrial applications in construction, aerospace, and the pharmaceutical sector.

Furthermore, research is focusing on creating bio-sourced aerogels from organic materials such as cellulose, starch, or rice bran. These alternatives offer better mechanical strength, greater flexibility, and a reduced environmental footprint. The European NanoHybrids project illustrates this dynamic by bringing together several industrial actors for the production of hybrid, nanoporous, and multifunctional materials, suited for large-scale industrialization.

Here is a summary table of the main processes and materials used in the manufacture of aerogels in 2025:

Type of aerogel	Base material	Manufacturing process	Major properties	Key applications
Silica aerogel	Silica (SiO2)	Supercritical drying	Ultralight density, excellent thermal insulation	Building insulation, aerospace, glasses
Organic aerogel	Cellulose, starch, agar-agar	Supercritical drying or chemical dehydration	Stronger, hydrophobic after treatment, biodegradable	Packaging, cosmetics, eco-friendly insulators
Hybrid aerogels	Combination of silica + biopolymers	Advanced hybrid methods	Increased durability, multifunctionality	Complex industrial applications, aeronautics

Innovative industrial applications of aerogels in thermal insulation and beyond

Aerogels find numerous and diverse uses in 2025, leveraging their lightness, extremely low thermal conductivity, and absorption capabilities. Originally used in space missions to insulate astronauts’ suits or capture cosmic dust, they are now becoming commonplace in the construction industry to improve energy efficiency while reducing bulk.

In modern construction, composite panels combining silica aerogels reinforced by fibers can replace up to half of the volume of traditional insulators like rock wool or expanded polystyrene, while offering better hygrothermal regulation. The reduction in thickness helps to preserve usable space in dwellings, a valuable asset in the face of growing demands for comfort and sustainable environment.

Aerogel also serves as a support in cutting-edge technologies: catalysts in the chemical industry, thickening agents in paints and cosmetics, or absorbent materials for pollutants in ecological devices. The high specific surface area and controlled porosity thus offer a wide range of complementary functions.

New aerogels composed of graphene and carbon also show significant potential due to their improved electrical conductivity and mechanical strength. The challenge lies in producing them at reasonable costs and on a large scale, which scientists aim to achieve in the coming years.

An inventory of current and upcoming applications:

• Thermal insulation for low-energy buildings and energy renovation.
• Thermal protection and impact absorption in aerospace.
• Ecological systems for capturing hydrocarbons and liquid pollutants.
• Supports in the production of lightweight and durable batteries.
• Composite materials for the automotive and aerospace industries.
• Innovative solutions in the medical and cosmetic fields.

Comparison of aerogels with other lightweight and high-performance insulating materials

The market for advanced materials in 2025 is thriving with several promising innovations, including aerogels. To better understand their position, a comparison with other ultra-light materials is necessary. Silica aerogels remain an essential benchmark due to their performance/lightness balance.

Among notable competitors, carbon-based materials, such as aerographite and aerogel, boast even lower densities, reaching as low as 0.16 mg/cm3 for aerogel. These porous nanostructures emerge as some of the lightest materials, with applications capable of absorbing up to 900 times their weight in liquids, revolutionizing environmental cleanup perspectives.

The table below summarizes the key characteristics of innovative lightweight materials, facilitating the understanding of their respective advantages:

Material	Density (mg/cm3)	Type of structure	Key properties	Main applications
Silica aerogels	0.16 – 0.30	Fractal nanoporous	Thermal insulation, partial transparency	Building, aeronautics, space
Aerographite	0.18	Pore network of carbon filaments	Ultra-light, electrode for batteries	Batteries, aeronautics
Aerogel (graphene aerogel)	0.16	Three-dimensional block structure	Extreme elasticity, high absorption	Environmental cleanup, electronics
Metallic micro-network	0.9	Pore nickel-phosphorus tubes	Strong, lightweight	Aeronautics, automotive

This comparison highlights the remarkable quality of aerogels against their competitors, as well as the vitality of research in materials innovation, which should continue to energize their performance in the years to come.

Future evolutions, challenges, and perspectives in the study of ultra-light aerogels

The future of aerogels looks promising due to a convergence between the optimization of manufacturing techniques and the diversification of their compositions. Silica-based materials are now well-mastered, but the intrinsic fragility of these aerogels pushes researchers towards hybrid alternatives, particularly organic or bio-sourced ones, capable of combining mechanical robustness and thermal performance.

A major scientific priority lies in reducing costs to enable large-scale diffusion, particularly in the field of ecological building, where demand for high-performing and compact insulators is booming. Ongoing work, supported both by European consortiums like NanoHybrids and private initiatives, aims to reduce prices by 30 to 40% by 2030, with even more ambitious goals in certain projects like SICLA.

Furthermore, multifunctionality is becoming an essential characteristic, combining thermal insulation with additional qualities, such as fire resistance, moisture resistance, or pollutant absorption capabilities. Biological research also inspires new avenues, such as composites inspired by natural materials like limpet teeth, for future ultra-resistant and lightweight composites.

Simultaneously, the use of these materials in energy technologies – particularly in high-energy-density batteries – opens new doors to sustainable mobility and reducing environmental impact. The combination of conductive aerogels from carbon or graphene with absorption and insulation capabilities marks a major step towards intelligent and adaptive materials.

For scientists and engineers, every discovery and improvement in the field of aerogels reflects not only technical excellence but also a commitment to addressing the energy and environmental challenges that define our time.

What is an aerogel?

An aerogel is an ultra-light solid primarily composed of air trapped in a porous nanoscale structure, often based on silica, offering excellent thermal insulation properties and very low density.

Why are aerogels excellent thermal insulators?

Due to their porous structure created by nanostructures, aerogels effectively limit the three modes of heat transfer: conduction, convection, and radiation.

What are the main materials used in the manufacture of aerogels?

Silica is the most common base material, but organic, bio-sourced, or hybrid aerogels combining biopolymers are now being developed.

What are the current industrial applications of aerogels?

Aerogels are used in thermal insulation of buildings, aerospace, capturing cosmic dust, cosmetics, chemical catalysts, and energy storage technologies.

What challenges remain for the popularization of aerogels?

Primarily the reduction of production costs and the improvement of mechanical strength to allow for large-scale industrial and commercial diffusion.