A traditional foodstuff from the Philippines may provide the key to developing a whole new generation of nanocomposite materials. Offering a range of environmental benefits, these 100% biodegradable materials could be used in car and aeroplane manufacture, batteries, medical implants and a host of other day-to-day applications.
Big breakthroughs sometimes come in unlikely forms. Take the potential impact of nata de coco, a low-fat, high-fibre food enjoyed in the Philippines for generations. Widely used in confectionery and desserts, this jelly-like product could solve a real scientific problem – how to produce nanocomposites that are genuinely eco-friendly.
Nanocomposites are made from two or more different materials, at least one of which has nanoscale dimensions (normally the reinforcement or a filler). They can also have remarkable qualities, such as great strength yet surprising lightness, which make them ideal for a whole variety of applications. But their growing role and undoubted value also create a potential disposal problem – how can we ensure nanocomposites don’t add to the world’s waste mountain when they reach the end of their useful life?
One option is to make nanocomposites from renewable materials that are completely biodegradable. For instance, cellulose fibrils (a fibril is a fine fibre with a diameter of around 1 nanometre) could be combined with other fibres such as hemp or sisal. It is vital, though, to ensure that the nanofibres are well linked to the material they are reinforcing. To date, it has simply not been possible to identify an environmentally friendly way of doing this.
But now scientists at Imperial College London and the University of Manchester may have pinpointed a solution. Nata de coco has all the right properties to act as an effective, biodegradable nanoreinforcement in nanocomposites made from renewable materials. “Nata de coco is made by fermenting coconut water using the bacterium Acetobacter xylium,” says Professor Alexander Bismarck of Imperial College. “It’s a tried and tested process. We can then take fibrils of the sticky nata de coco produced and apply them to other fibres. The result is a really secure bond between the two.”
In this way, nanocomposites can be made from 100% renewable materials and will be not only completely biodegradable but recyclable and compostable too. Moreover, the precise mix of components can be adjusted to suit particular applications. The team is now focusing on how nanofibres will interact with other materials in such nanocomposites, as well as on the potential to achieve weight savings without reducing strength – essential if solid foams are to be produced for construction uses.
“We’re opening up ways of developing a whole new breed of truly ‘green’ nanocomposites,” says Dr Steve Eichhorn of the University of Manchester. “Nata de coco has undoubtedly given us a real taste of success!”