If you ask a materials scientist to choose a material, the first things they will think about are things like strength, fracture toughness and stiffness – the fundamental mechanical properties that characterise the material. A materials technologist will consider these properties too, but into the equation will also go how much the material costs and how easy it is to manufacture. But when a consumer is deciding whether to buy a product made from the material, it’s not numbers like the fracture toughness that swing the decision. It’s much more intangible qualities, the way the material looks and feels, and the way the design integrates the properties of the component materials with the form of the object, that determine whether the purchase is made, the price the product can command, and in many cases the pleasure that the consumer gets from owning and using the artefact. We can create new materials with controlled nanostructures, designing combinations of properties like strength and toughness to order. But who’s thinking about how to design those human-centred properties that are so important in giving value to materials? Only engineers care about fracture toughness, and most people aren’t engineers.
These reflections arise after a day spent in the London offices of the design house, the Conran Partnership. A small group of scientists, on the one hand, and designers, on the other, met to talk about industrial design, what’s good and bad about plastics, and whether there’s any way in which one could relate the emotional response of a consumer to a material to some scientific description. Some things are obvious – the heft that comes from high density, the apparent coldness of metal that comes from its high thermal conductivity. Some are less obvious, though – why is the anodised aluminium finish of my Apple Powerbook quite so desirable? It’s clearly something to do with roughness and texture, but what, exactly? And what about the time dependence of these qualities – what is it about leather, hardwoods and natural stone that make them age so gracefully?
The promise of nanotechnology – even the incremental kind that is a natural development of the last fifty years of materials science – is that it will allow us to design materials with properties to order. Because materials development is done by scientists and engineers, the properties that we tend to concentrate on are the physical ones like strength and stiffness. Now we need to understand the other factors that make an object desirable so we can design materials that fulfill those needs.