MSE 09 Home-made Aerogels
- Jinwook Chang
- Jan 3
- 8 min read
Explore how to make a lightweight, porous, and insulating aerogel alternative at home using simple materials to mimic the remarkable properties of real aerogels.
Introduction
Aerogels are a type of special solid material that combines an unconventional appearance with remarkable functional properties. Aerogels are sometimes described as solid air due to their translucent look. They are some of the lightest solids that have ever been produced. They are not only known for their lightweight characteristics relative to the volume they occupy, but also for their unique combination of low density, high porosity, large surface area, and extremely low thermal conductivity.
A typical aerogel consists of a solid framework in which the majority of the volume, which is often over 90%, is space filled with air or another gas. This open framework, usually composed of silica, carbon, or metal oxides, is created by replacing the liquid component of a gel with a gas without collapsing the gel’s delicate solid structure. In both industrial and research contexts, this is achieved using a process called supercritical drying, where the liquid is removed under conditions that bypass the liquid–gas phase boundary. This method avoids the destructive forces that would otherwise collapse the microscopic architecture of this material.
Since the invention of silica aerogel in 1931 by Samuel Stephens Kistler, the material has been investigated for a wide range of uses, from aerospace insulation to environmental cleanup. NASA has famously used silica aerogels to capture high-speed cosmic dust particles in space, while on Earth, aerogels have been employed in cryogenic insulation, energy-efficient construction, and even advanced sporting equipment.
However, producing high-quality aerogels requires precise, resource-intensive processes that are not easily replicated. In this experiment, we will create an aerogel alternative – a simplified version that mimics some of the key properties of real aerogels (low density, high porosity, and insulating capacity) using safe, inexpensive, and widely available materials. While our results will not achieve the same nanoscale structure or performance as genuine aerogels, they will still be able to effectively demonstrate the core concepts and physical principles.
This simplified approach allows students to understand key concepts regarding porosity, thermal conductivity, and materials science without the need for specialized laboratory equipment or hazardous chemicals. The finished product, while coarser and denser than a normal aerogel, will be similar in appearance and performance compared to more familiar solid materials.
Aim
This experiment aims to produce a lightweight, porous, and insulating solid material using household ingredients, in order to simulate some of the structure and functional characteristics of a true aerogel.
The experiment aims to:
Demonstrate how increasing a material’s porosity will reduce its density and improve its insulating properties.
Compare the effects of different base materials (silica gel beads versus cornstarch) on the resulting product.
Investigate how binder choice, gelatin versus polyvinyl alcohol (PVA) glue, affects structural rigidity, flexibility, and pore size distribution.
Evaluate the thermal insulation performance of the aerogel alternative against conventional materials such as plastics and metals.
Context
Real aerogels are high-value, high-performance materials that have found niche applications in fields where their unique combination of properties offers distinct advantages over other, more conventional materials. In aerospace, aerogels have been used as lightweight insulation for spacecraft, helping protect sensitive instruments from extreme temperatures without adding significant mass. During NASA’s Stardust mission, silica aerogels were used to capture cosmic dust particles traveling at several kilometers per second, slowing them without destroying their structure.
In construction, aerogel blankets and panels provide insulation values that are far superior to traditional fiberglass, enabling the refurbishment of historic buildings without dramatically altering their appearance or wall thickness. In environmental engineering, hydrophobic aerogels can absorb many times their own weight in oil while repelling water, making them useful for oil spill cleanups.
Despite these benefits, the widespread use of aerogels is limited by production challenges. Drying equipment used to create aerogels is expensive and energy-intensive. Producing aerogels with uniform nanostructures requires strict control over drying conditions. Even more accessible ambient pressure drying methods require precise solvent exchange processes to prevent shrinkage and cracking when producing aerogels.
Materials
Base material:
Silica gel beads (commonly found in desiccant packets) or corn starch (alternative for simplicity).
Binder:
Gelatin or PVA (polyvinyl alcohol) glue.
Solvent:
Distilled water or alcohol.
Mold:
Small plastic container, silicone mold, or flat tray.
Drying method:
Freezer or a drying agent (e.g., silica gel packets).
Tools:
Mixing bowl, spoon or spatula.
Optional additives:
Food coloring for visual effects.
Procedure
Step 1: Prepare the Mixture
Dissolve the Binder:
Heat 1 cup of distilled water in a mixing bowl.
Add 1 tablespoon of gelatin or 2 tablespoons of PVA glue and stir until fully dissolved.
Add Base Material:
Gradually mix in 2 tablespoons of silica gel beads or corn starch until evenly distributed.
Optional Customization:
Add a drop of food coloring for colored aerogel-like materials.
Step 2: Form the Gel
Pour into Mold:
Pour the mixture into your chosen mold or tray, ensuring it is spread evenly.
Set the Gel:
Allow the mixture to cool and solidify into a gel-like state. This may take 30–60 minutes at room temperature.
Step 3: Dry the Gel (Simulating Aerogel Porosity)
Freeze-Drying Method (Preferred for Porosity):
Place the gel-filled mold in the freezer for 12–24 hours.
After freezing, transfer the gel to a container with a desiccant (e.g., silica gel packets) to absorb residual moisture over several days.
Air-Drying Method (Simpler but Less Porous):
Leave the gel to air dry in a well-ventilated area for 2–3 days until it becomes light and rigid.
Step 4: Analyze the Result
Inspect the Material:
The dried product should be lightweight, porous, and somewhat rigid, resembling an aerogel.
Test Properties:
Check insulation by placing the material over a warm surface (e.g., a cup of hot water) and observing how well it prevents heat transfer.
Test strength and flexibility by gently pressing or bending the material.
Observations
Texture and Weight:
Note the lightweight and spongy or brittle texture of the dried material.
Porosity:
Use a magnifying glass to observe the fine pores or network structure.
Insulation:
Compare the heat transfer properties of your material to a standard material like plastic or fabric.
Analysis
Binder Effect:
Experiment with different binders (gelatin vs. PVA) to observe differences in strength and porosity.
Base Material Variations:
Test the process with other materials (e.g., starch, sawdust) to explore alternative lightweight composites.
Applications
Explore the principles of aerogels used in thermal insulation, soundproofing, and lightweight structural components.
Understand how porosity and material composition affect strength and heat transfer.
Theory
The properties of both true aerogels and our simplified alternative are dependent on two main factors: porosity and thermal conductivity.
Porosity and Density:
Porosity is the fraction of a material’s total volume that is empty space (voids). The higher the porosity, the lower the overall density. Air has a density of only 0.001225 g/cm³ at room temperature, so replacing most of a solid’s volume with air significantly reduces its density.
Thermal Conductivity:
Heat transfer occurs in solids through:
Conduction: energy transfer via particle collisions in the solid framework.
Convection: movement of air or liquid within pores.
Radiation: emission of infrared energy through the material.
Aerogels have extremely low thermal conductivity since:
Their sparse structure reduces conduction through the solid phase.
Nanometre-scale pores prevent significant convection.
Radiative transfer can be minimized with certain additives.
In our version of aerogels, pore sizes will be larger (on the micrometer to millimeter scale), so convection will contribute more to heat transfer, making it less insulating than true aerogels. However, conduction through the solid will still be reduced compared to dense solids, which will mean that it is still able to showcase an insulating effect.
Observations
During the course of this experiment, several consistent patterns can be observed depending on the choice of base material, binder, and drying method. While results will vary slightly depending on specific environmental conditions, some key observations can still be made.
Silica gel base: When crushed silica gel beads are used, the dried product often has an irregular, somewhat brittle structure. The material tends to be pale, with a rough, chalk-like surface. Under magnification, a network of pores and voids can be seen, though these are significantly larger than those in a true aerogel.
Cornstarch Base: This base produces a more uniform, slightly smoother texture. The pores tend to be smaller and more evenly distributed, leading to a more spongy or foam-like appearance.
Binder’s impact:
Gelatin: Using gelatin will create a more elastic structure that resists shattering and is more resistant to deformation under mechanical stress. The resulting material bends slightly before breaking and feels more organic to the touch.
PVA Glue: Using PVA glue instead produces a stiffer material that is more prone to snapping cleanly under mechanical stress. The pore walls are also thicker.
Qualities of Aerogel
The final aerogel-like materials produced in this experiment exhibit several notable characteristics, such as:
Low Density, as even without achieving the ultra-low densities of real aerogels, our aerogel alternative is still significantly lighter than common solids of similar size.
Thermal Insulation, when placed between a heat source, for instance a blowtorch, and a temperature probe, the material noticeably slows heat transfer compared to thin sheets of plastic or metal.
High Porosity. When looking at the aerogel, you can see a network of interconnected voids. Whilst these are much larger than the nanopores of true aerogels, they still reduce the amount of solid material in a given volume and still help with insulation by reducing heat loss via convection.
Customizability, changing the base material, binder, or drying method, a wide range of textures, strengths, and densities can be achieved.
Economic & Environmental Factors
True aerogels are expensive, often costing several hundred pounds per kilogram due to the cost of raw materials, energy-intensive drying processes, and specialized equipment. In contrast, this simplified alternative can be produced for much due to being produced with cheaper materials. The economic advantage of aerogels appeals to construction businesses, where balancing the cost of insulating materials with performance is important, as aerogels offer a far superior level of insulation than other traditional forms of insulating material.
Aerogels present both environmental opportunities and challenges. Their exceptional insulation performance reduces energy demand in buildings and aerospace applications, lowering greenhouse gas emissions over time by reducing overall energy lost via heat energy. However, their production is energy-intensive, requiring supercritical drying and solvent exchange processes that consume a lot of resources and generate a lot of waste. Silica aerogels are chemically inert and non-toxic, meaning they pose minimal disposal and contamination risks, whilst organic or biodegradable aerogels are being developed to further improve sustainability.
Applications
While the version of aerogels produced here cannot replace real aerogels in demanding applications, real aerogels have enormous application potential:
Aerospace and Space Exploration: It can be used as thermal insulation on spacecraft and suits. NASA has already used silica aerogels to capture cosmic dust during the Stardust mission.
Construction and Architecture: Aerogel blankets and panels provide superior insulation, allowing energy-efficient refurbishments of buildings without bulky materials.
Environmental Cleanup: Hydrophobic aerogels absorb oil many times their weight while repelling water, and are useful in oil spill remediation.
Clothing and Sporting Goods: This material can be integrated into jackets, boots, and gloves for lightweight warmth.
Conclusion
This experiment demonstrates that it is possible to create a lightweight, porous, and insulating solid material using household ingredients and effectively simulates some of the properties and characteristics of real aerogels. While our version lacks the nanoscale architecture and performance of true aerogels, it can still be used to investigate the properties of real aerogels, mimicking their performance.
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