It's an advanced material world
Glossary
amphiphilic (`loving both'). One end of an amphiphilic molecule is polar and hydrophilic (water loving) and the other is non-polar and hydrophobic (water hating). The hydrophilic ends of the molecule point outwards into the solution and the hydrophobic ends point inwards away from the water, so they tend to self-assemble in water. Amphiphilic materials are already widely used, but research into their use for drug delivery and ultrasound imaging is relatively new.
auxetic materials. Grow fatter when stretched and thinner when compressed – the opposite of a rubber band. Auxetic materials are resistant to impact, so they have possible uses as car bumpers, gaskets in engines, soundproofing and in bullet-proof vests. For more information see Background (Auxetic Materials Network, UK) and Auxetic materials – applications (Azom.com).
biomaterial. A synthetic material used to replace part of a living system or to function in living tissue. A biomaterial is different from a biological material in that it is engineered rather than being naturally produced by a biological system.
ceramics. Are inorganic, non-metallic solids processed or used at high temperatures. A ceramic is made by combining metallic and non-metallic elements. Traditional ceramic products such as clay pots and chinaware are hard, porous and brittle. Modern ceramics are used to create bones and teeth, cutting tools or to conduct electricity. For more information see Advanced ceramics (Azom.com) and About ceramics (The American Ceramic Society).
composites. Are formed by combining two or more materials that have quite different properties. The different materials combine to give the composite unique properties, but within the composite you can easily tell the different materials apart – they do not dissolve or blend into each other. Fibreglass is a composite material made from glass fibres which give it its strength and a flexible polymer resin (matrix) that binds the fibres together. For more information see Putting it together – the science and technology of composite materials (Nova: Science in the news, Australian Academy of Science).
immune system. The cells, tissues and organs that assist the body to resist infection and disease by producing antibodies and/or altered cells that inhibit the multiplication of the infectious agent.
Kevlar. Kevlar is a synthetic polymer fibre and is used when reduced weight, increased strength and long wear life are required. The tensile strength of Kevlar is more than three times greater than that of steel, and its density is less by a factor five, so it is ideal for making very strong, light, flexible structures. It has become a household name, being used for yacht sails, bullet-proof vests and in the aerospace industry.
metal alloys. Metal mixtures with greater strength, hardness or malleability than their component metals. The ratio of each component determines the properties of the alloy. Modern alloys may be created by adding just a few per cent of another metal.
neoprene. The DuPont name for a synthetic rubber fabric made from polymers of chloroprene. While it can only stretch a little, it is very strong. Because of its durability, neoprene is used for many industrial and commercial applications.
polymers. Polymers are large molecules that are made up of many units (monomers) linked together in a chain. There are naturally occurring polymers (eg, starch and DNA) and synthetic polymers (eg, nylon and silicone). More information can be found at The basics – polymer definition and properties (Plastic Resource, USA), Introduction to polymers (Case Western Reserve University, USA) and History of polymers and plastics for teachers (Hands On Plastics, American Plastics Council).
polymers of intrinsic microporosity (PIMs). Are organic polymers that are porous to certain substances and not to others, so they can filter out target molecules. They are useful in industrial processing, medical technologies and in the laboratory, and can supply clean drinking water.
protein. A large molecule composed of a linear sequence of amino acids. This linear sequence is a protein's primary structure. Short sequences within the protein molecule can interact to form regular folds (eg, alpha helix and beta pleated sheet) called the secondary structure. Further folding from interaction between sites in the secondary structure forms the tertiary structure of the protein.
Proteins are essential to the structure and function of cells. They account for more than 50 per cent of the dry weight of most cells, and are involved in most cell processes. Examples of proteins include enzymes, collagen in tendons and ligaments and some hormones. More information can be found at Protein structure and diversity (Molecular Biology Notebook, Rothamsted Research, UK).
semiconductor. Is a material that conducts electricity at a level between an insulator and a conductor. The electrical properties of semiconductors can be controlled by adding small amounts of other atoms or impurities – called doping. Transistors made from semiconductors are used in all electronics including computers, mobile phones, calculators, CD and DVD players. Some semiconductors can also be made to emit light when exposed to an electric field, including diode lasers and light emitting diodes, or LEDs. Silicon is currently the most widely used semiconductor in computer chips and other electronic components. For more information see How semiconductors work (How Stuff Works, USA).
spintronics. Also known as ‘spin-based electronics’, is the science of using electrons to store data. It uses the charge on an electron as well as its ‘spin’ state to store ‘qubits’ of information. Spintronics may lead to a new way of calculating called quantum computing. For more information see Spintronics (Nanotechnology Now) and Spindoctors (PC Magazine, UK).
superconductor. A substance that has no resistance to the flow of an electric current. Superconductors currently require very low temperatures to function. They can be used for energy storage, storing and retrieving digital information, medical imaging machines and friction free transport. For more information see What is superconductivity? (How Stuff Works, USA) and Superconductor information for the beginner (Superconductors.org).
teflon. A polymer of fluorinated ethylene with the chemical name polytetrafluoroethylene (PTFE). It was invented in 1938 and is one of the most slippery substances ever made.
Page updated August 2006.