Aerogels also known as Frozen smoke an exceptional light weight material

Aerogels - an exceptional light weight material

chemistry of Aerogel



Aerogel was created by Steven Kistler in 1931 and it has become a material of interest to scientists in recent decades due to its light weight.  Aerogel is a synthetic porous ultralight material derived from a gel, in which the liquid component of the gel has been replaced with a gas. It is an advanced material which holds 15 entries in the Guinness Book of Records for properties such as lowest density solid and best insulator. It is a silica-based substance, consisting of a loose dendritic network of the atom silicon.


According to research network, the market for aerogels by 2013 is estimated to be $646.3 million with a compound annual growth rate of 50.8 per cent. Aerogel is also called as ‘Frozen smoke’ and it consists of 99.8 per cent of air. It can be used at temperatures between -200°C to +600°C. Aerogel is having following characteristics


Characteristics of aerogel

  • Low thermal conductivity
  • Hardness
  • Heat resistance
  • Transparency
  • Elasticity
  • Insulation
  • Durability
  • Flexibility


Types of aerogel


Aerogels can be divided into following types based on composition from which they are made


Silica Aerogel – it contains silica-based substances

Metal Oxide Aerogel – these can acts as catalysts

Carbon Aerogel

Organic Aerogel – it is comprised of organic polymers such as

  • Resorcinol
  • Formaldehyde
  • Phenol formaldehyde
  • Melamine formaldehyde
  • Cresol formaldehyde
  • Phenol furfuryl alcohol
  • Polyacrylamides
  • Polyacrylonitriles
  • Polyacrylates
  • Polycyanurates
  • Polyfurfural alcohol
  • Polyimides
  • Polyacrylates
  • Polycyanurates
  • Polyfurfural alcohol
  • Polyvinyl alcohol dialdehyde
  • Polystyrenes
  • Polyurethanes
  • Agar agar
  • Agarose


Alumina Aerogels – it contain aluminium oxide

Semiconducting Metal Chalcogenide Aerogels

Metal Aerogels

Cryogels Aerogels – it is used in

  • Sub-ambient piping and equipment
  • Cryogenic storage
  • Sea transport
  • Industrial gases
  • Liquefied natural gas (LNG) import/export pipelines
  • Chilled water systems
  • Gloves
  • Jackets
  • Sleeping bags


Spaceloft Aerogels – it is used in

  • Building and construction
  • Heating, water and conditioning systems
  • Household appliances


Pyrogel Aerogel – it is used in


  • Aerospace and aeronautic transportation
  • Fire protection equipment
  • Industrial and petrochemical equipment
  • Power generation equipment




Aerogels can be prepared by using

  • Alumina
  • Chromia
  • Tin oxide
  • Carbon


But apart from these materials used for making of aerogel, silica based aerogel is preparation is easier and reliable.


  4 to 30 times more water is added to Tetraethylorthosilicate (TEOS) in the presence of ethanol it leads to the further chemical reaction


Si (OCH2CH3) 4 (liq.) + 2(H2O) (liq.) → SiO2 (solid) + 4(HOCH2CH3) (liq.)


Fig. 1) Aerogel preparation method



Final product density is mainly depends on the concentration of silicon alkoxide monomers in the solution. After gelification, the gel is left undisturbed in the solvent for 48 hours to complete the reaction. Once reaction will complete the alcogel product will form. The alcogel is then submitted to supercritical drying.


The final products formed in this reaction are

  • Aerogel
  • Xerogel


Applications of aerogel

Aerogels are being used by NASA for collecting micrometeoroids in space. As aerogels are highly transparent, the captured micrometeoroids and their paths through the material can be studied easily.

Aerogels are being developed as catalysts to promote chemical reactions and as


  • Sound insulators
  • Elements in sonic range-finding devices used by automatic focus cameras
  • Cherenkov radiation detectors in nuclear reactors
  • Insulators in refrigerators, replacing foam plastic



Aerogel particles are used as thickening agents in some paints and cosmetics

Aerogel can be used as a drug delivery system owing to its biocompatibility

Aerogel can introduce disorder into superfluid helium-3

Aerogels are being tested for use in targets for the National Ignition Facility

It is used in batteries, Capacitor electrodes, low dielectric constant material, porous piezoelectric transducers, and catalysis process



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