Re-imagining Our Relationship with Materials

15 July 2019

MATERIAL-WORLD

Layers of various circular materials

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Wherever you are, take a moment to look around and count how many materials you can see…

How far did you get before you started to lose track? No doubt there are all kinds of metals, woods, masonry, plastics, textiles and more, and that’s before you start to consider composites, where multiple materials are brought together and combined to make new ones.

How did so many materials come to surround us, performing all kinds of useful and aesthetic functions, when often we barely even notice they are there? And what does the future look like for them, as such a fundamental part of our daily lives?

Materials in the past

Historically, the importance of materials has defined civilisations and their development, which is where names such as the Stone Age, Bronze Age and Iron Age all come from. The materials that become dominant during an era are vital for anthropologists and archaeologists to understand entire cultures and distinguish between them, and see how our human world has evolved.

But the use and advancement of materials never stands still, meaning that new ones are created, many are improved, and some that were useful at first fall out of use entirely. Thankfully, the use of copper containing poisonous arsenic has been left in the Bronze Age [1] and the lead first used in pipes and waterways by the Romans was eventually phased out, then completely banned across Europe by the 1970s [2] due to its ability to impair mental development. Despite these and other similar cases though, the use of lots of materials has stood the test of time.

The first porcelain dates from 600 CE in China [3] and shares strong similarities to what we still produce today. The same can be said of steel, which was first produced in India in 400 BCE by infusing carbon into iron using charcoal. Used for weapons and armour ever since, the Japanese went on to produce particularly revered examples for their katana swords from the 14th Century onwards [4], and were masters of steel in their day.

Present day materials

Since then, steel has become a versatile material found all over the world, centuries later used to construct the buildings we live in, the tools and appliances we use, and the transport that moves us around. Society would be a different place without it, as with many of the other materials we barely notice day to day. So how did a material like steel, initially created with a specific purpose, become so versatile and diverse in its uses?

The relevance of a material today is related to how its properties, availability, cost, manufacture, safety and - increasingly - environmental impact all come together to create demand for a particular purpose. Steel and porcelain were first created through relatively fortunate circumstances: the right ingredients in the right place put together in the right way. And then through many generations of trial and error, manufacturing techniques and the resulting properties of the materials improved. Nowadays we use advanced equipment and techniques to analyse how a material behaves and why, at levels small enough to understand what even single atoms are doing and how they are contributing.

This allows a more design-led approach to developing new materials. Rather than scientists applying a material they’ve found by chance for a particular purpose, they can now have a particular use in mind and research ways to enhance materials they already have, or create entirely new ones to do a job.

This was the case with the development of carbon fibre reinforced polymers, or what most people call carbon fibre. This smooth grey-black material with a weaved pattern offers high strength but at low weight, so you see it used for high performance applications such as plane fuselages, car bodywork and sports equipment, even prosthetics. It didn’t exist until the 1960s [5], when carbon fibres were combined with polymer resins and allowed to set together, creating a new, composite material with better performance than either of the individual parts alone.

This was revolutionary, as the fibres are woven into a mat and provide high strength in the direction they are oriented, whilst the polymer resin binds them together and makes them rigid. By adjusting how much of each is used and in what orientation, the properties of this high performance material can also be adapted, either making it very stiff for a bike frame, or flexible for an aircraft wing, but strong and lightweight in both cases. This carbon-based material made a substantial impact in the 20th Century and it is unsurprising that a new one, graphene, is seen to have so much potential in the 21st. But creating new materials is not the only option.

The future of materials

As an example of a material enhanced by science, how about super bainite, a high strength steel developed by scientists in Cambridge [6]. It uses a special production process to create billions of steel crystals inside the steel, 1/10th the size of those found in normal steels. These crystals create boundaries that strengthen the material far beyond what is usually expected. This was a breakthrough in the field. However, super bainite is relatively brittle and if made into a simple, flat sheet, likely to shatter when hit with a bullet.

So the team took their idea further, and by designing sheets of super bainite to have a pattern of oval holes within it, made the material tougher, allowing it to stop bullets but still remain intact after an impact and continue to work effectively. This is an example of how the overall structure of a material can have a dramatic impact on the material itself.

This shows that through design and development of modern materials, we are no longer limited to what goes into the material defining how it works. Getting creative with the entire design process allows all kinds of new possibilities to open up, by re-imagining the structure of our materials and using their form to serve a purpose. And this is where the future of materials research lies.

Metamaterials demonstrate this idea brilliantly because it is their structure that gives them their properties, not just what they are made of. This means they have even been touted as a way that real invisibility devices could be created! What makes this possible is that the surface structures of the metamaterials are designed in such a way that they can interact with light, potentially bending it around an object rather than blocking it, so you see not the object, but what is behind the object instead. And in a different application entirely, metamaterials have now been used to interact with other electromagnetic waves, like microwaves, to solve complex mathematical equations [7], again all due to their cleverly designed structure.

Using this metamaterials concept, research is being done into metamaterial mechanisms, where the structure of a material is its function. Researchers have shown that it’s possible to use 3D printers to create pliers, entire door latch assemblies, and more. These objects use clever mechanisms built into the material to serve their function [8], which means no separate parts and no assembly, simply a working device from the instant it is made. So whether it’s astronauts printing tools in space or you being sent digital designs for parts you can make and use in your home, the way we think about materials technology is changing. The design process too!

For instance, even the computing tools scientists might use to design are being pushed in new directions. Where once the human input into design was used to create concepts that might later be refined by computer optimisation, now the systems themselves are able to be ‘creative’.

Generative design provides computer algorithms with a set of outcomes that need to be met, but then allows the system to try any possible combinations of designs, some of them so bizarre they may not have been thought of by humans. The designers can then assess the merits of the new range of designs and optimise them as necessary.

NASA have used this method to create an interplanetary lander [9], fulfilling the same function as their initial design, but vitally for space travel, using 35% less material. Saving material or being more efficient with its use is not only limited to highly specialised applications in space though; it will define the future of our planet and the environment we have to live in.

Imagine your own materials, change the world

As we become ever more affected by climate change and the huge levels of waste we produce that pollutes our surroundings, it is necessary for us to change our entire approach to the materials we have available and how they are used. At the moment, materials are  often extracted in one part of the world, processed in another part, used somewhere else, then disposed out of sight elsewhere, with minimal recycling of these valuable and limited resources.

Natural systems have developed to do the opposite, with ecosystems that pass the building blocks for life through an extended cycle so they are never lost, but contribute their materials to the next phase in the food chain. Unlike us, they use local materials and are highly efficient recyclers, but we could do the same if we changed our approach. Materiom [10] is a platform that could help us all do just that, at home, with a big impact that at the moment it might be hard to imagine an individual could make.

It is a growing open source recipe database of materials developed from natural resources like gelatin, agar, resin, shell and clay amongst others. It means anyone can source basic materials local to them, experiment, then create entirely materials and upload their recipes, with possible alternatives to plastics, leather and earthenware already available. Ideas like this are changing our relationship with materials and empowering people. This is an example of crowd-sourced knowledge to enable people to develop, use and keep re-using materials around them without detriment to the environment. But who knows what other brilliant materials ideas are just waiting to be thought of, and that you can contribute to.

Even in the short time you’ve been reading this, we’ve been on a long journey from the first materials used by ancient civilisations, through to an industrial age where materials diversified dramatically. And then onwards to the present where materials aren’t just what things are made of, but where structures themselves also define a material, where design takes a leading role, where there are possibilities to re-imagine the entire palette of materials we use, and even create new ones ourselves. It's no longer just up to science labs and big companies to make developments of material discoveries. In fact the cutting edge of materials research is limited only by your imagination. So, over to you...

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