The Miracle Material - Aerogel

by Max Harvey

Ever since early humans first roamed the Earth, our species evolution as a civilised race and our ability to further our technological advancement has to some extent been only limited by the materials that we have had available to us. The first big leap into this world of materials came through the bronze and iron ages which enabled the construction of permanent dwellings through the innovation of metal tools, and turned homosapiens from hunter gathers to settled farmers. Since then, the development of tools and products has increased at an exponential rate and ingenious inventions such as the lightbulb, the internet and the very electronic device that you are probably reading this on have sprung into our everyday lives.

Yet despite our amazing and incredible designs and discoveries, it is the scientists' nature to desire an even greater understanding of the materials that make up the objects that surround us each and every second of the day, and this has led to the increased popularity of material science.

From this rapidly expanding specialised division of the science community emerge some of the most fascinating discoveries in the modern day. No doubt many of you have heard of graphene, the material hundreds of times stronger than steel yet only a single atom in thickness, but there exists a whole plethora of similarly brilliant materials that possess even more peculiar characteristics.

The material that in my opinion epitomises the talent of the material scientists is silica aerogel. Second only to another from of aerogel, graphene aerogel, silica aerogel is the lightest material on Earth and is also one of the best thermal insulators known to us, so good in fact that it is the insulation of choice for many of the Mars Rovers.  The first aerogel material was first invented in the 30’s by Samuel Kistler and its origin is more unexpected than you might think.

Kistler stumbled across aerogels when he was considering jelly. Yes that rights, the edible jelly that nearly everyone has eaten at least once. Kistler knew that it was neither solid nor liquid but concluded that it was almost like a liquid that was held in place by an invisible, yet solid, net. However the actual basis of aerogel came when Kistler decided to see if the internal skeleton of the jelly could be separated from the liquid. What followed was a long and problematic process to extract the mesh from within the jelly involving many trials of different solvents and varying techniques. Eventually however, Kistler, with the help of some colleagues, was able to remove the internal skeleton by essentially tricking it into not realising that the liquid inside of it has been replaced with a gas.

This process was then repeated but using silica dioxide, what glass is made out of, which produced the silica aerogel. This aerogel in particular is 99.8% air and has a slight blue tinge when placed against a white background. The nature of its makeup is what makes it such an excellent thermal insulator. The millions of tiny air pockets within the skeleton of the aerogel enable the material to act like millions of layers of double glazing with each individual pocket preventing the transfer of heat. This is what has enabled it to be such an excellent insulator.

Despite the amazing properties of aerogel Kistler only ever saw his invention used as a thickening agent in bomb production and even in that capacity it was quickly replaced by cheaper alternatives.

However, in the early 80’s silica aerogel began its long road back to glory. NASA soon were using it to insulate sensitive instruments in space and with its fractional weight, aerogel soon became a must for space exploration. In addition to this though aerogel had another incredible use. Space dust. Wouldn’t it be great if we were able to capture some intact space dust from possibly out of our solar system and study it? Well it's a good thing that aerogel was trialed for this purpose as it enabled these particles of space dust to be captured without capturing them.

Not only can one see here the amazing properties of this material but more importantly how the materials that we have synthesised in our high tech machines often have many different uses across vastly varying fields. It often takes years before the perfect use of a material is recognised and only then can it come into the spotlight and aid scientific discovery. The future for aerogel is still unclear though; maybe it will be ousted by a new compound, or perhaps it will remain and the undisputed champion of the insulators. Regardless of whether it ends in fame or fail, who knows what other materials are yet to be discovered and which ones could be repurposed for unthought of situations.