Material Facts about Chemistry
From molecules to materials, chemists are making key contributions to things that matter. Everything real is made out of materials. The successes of technology, the comforts of home, the freshness of food, and the health of our minds and bodies all need the right molecules to be organised in the right way. Our lives, lifestyles and future are shaped by materials.
Chemists are at the centre of the action to develop new materials. They are significant players, mixing it up, creating the recipes for material success. To make stuff that works, a materials chemist has to be highly innovative and not bound by convention. For example, plastics are well known for their electrical insulating properties, yet many materials chemists are involved in making plastics that conduct. Why would we want a conducting plastic when metals can do that job quite adequately? The answer lies in the combination of properties that conducting plastics can offer. Their low density makes them attractive for use in the wiring of an aircraft, where weight saved equals fuel saved and cash in the bank. Their optical properties make them applicable in new-generation computer displays. Indeed, ultra-lightweight, robust, energy-efficient computers in which almost all the electronic and display components are made from plastic will be with us soon.
Materials chemistry is about making new molecules and compounds - but that's just a small part of the story. Consider the tiles that cover the surface of the space shuttle. They are made from the same stuff as the glass in a quartz-halogen headlight. What sets space shuttle tiles apart from other types of heat-resistant glass is the way in which they are structured. The tiles consist of fine glass fibres organised in an open cellular pattern, so that tiny spaces account for 95% of their volume. They are thermally insulating and lightweight - unlike the glass in the headlight. So the properties of a material don't just depend on its composition, but also on how the constituent atoms and molecules are arranged.
Materials chemists are concerned with the health of the environment and the wise use of natural resources. They search for ways to increase the use of commonplace ingredients and energy-efficient processes in the production of advanced materials, minimising environmental impact. One example of this approach is the fabrication of high-tech, easily processed ceramic materials starting with beach sand and antifreeze(!) Such ingredients are readily available, and the energy saving is substantial compared to the conventional way of making ceramic objects by grinding, compacting and firing powders.
As well as considering the environmental consequences of their inventions, materials chemists study how materials respond when exposed to particular environments. They learn about the physical and chemical agents that cause materials to fall apart. This knowledge is used to find ways to protect materials from degradation by heat, ultraviolet light and chemical attack. And by characterising the current condition of a material - its composition and the way in which its molecules are organised now - it is possible to deduce details about the loads and environments that the material has been exposed to in the past. In other words, materials chemistry can play an important role in the forensic analysis of crime and disaster scenes.
Sometimes new materials behave in ways that were previously unheard of. Imagine a mirror made from material that reflects light back along the path of the incident ray, instead of obeying the usual laws of reflection. What would you see if you could stand in front of one?* Or imagine shining an infra-red (invisible) beam of light into a material, and seeing bright green light come out. Chemists are making materials like these. They are called non-linear optical materials, and they have many unusual and useful properties. They are applied in new types of opto-electronic device that enable high-speed, high volume image processing and data storage.
[*Answer: Just a pair of eyes, staring back at you from whatever spot on the mirror you happen to be looking at......]
Materials chemists with an eye on the future have yet another target in their sights: they are learning how to synthesise molecules that can self-assemble into useful materials. Self-assembly means that the molecules are pre-designed to organise in a way that leads to desirable properties in a material, without recourse to the energy-intensive procedures and aggressive environments that are called for in conventional materials processing. The term supramolecular materials chemistry is used to describe this new approach.
In fact, supramolecular materials chemistry has been around for a very long time. It's how Nature makes all its materials and even its most complex devices. Nature has had 4 billion years in which to get it right, so the plants and animals that we see today are evolutionary success stories in the material world. Biomimetic materials incorporate Nature's lessons for selecting and organising molecules. They are (of course!) fully compatible with the natural environment. Some spider silks have tensile properties that outperform those of any kind of artificial fibre, and, although the fibres are insoluble in water, they are spun from an aqueous solution of protein. Spider silks are therefore teaching us a lot about the types of molecule and molecular arrangement that promote simultaneous high strength, high stiffness and high toughness in a material. They are also teaching us about how such a material can be self-assembled under environmentally benign conditions.
Would you like to make a substantial difference to progress in these exciting endeavours? You can start by enrolling in a degree programme that leads you to the most recent developments in materials chemistry. Look for a department in which the teaching is closely linked to interesting research and the publication of thought-provoking ideas. Equip yourself for an expedition to the frontier. Then help to create the stuff of dreams, of headlines and of tomorrow.
Author: Christopher Viney, MA PhD FASM CPhys FInstP CChem FRSC, Heriot Watt University
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