3·2 Smart and modern materials LEARNING OBJECTIVES By the end of this section you should: ✓✓be aware of a range of ‘smart and modern materials’, including thermochromic materials; polymorph; shape memory alloy (SMA); shape memory polymer ✓✓understand the key properties of common ‘smart and modern materials’.
What are smart and modern materials? ‘Smart and modern materials’ is an umbrella term for a wide variety of materials whose properties alter depending on environmental conditions, such as light, temperature or movement. These materials are designed and manufactured through scientific discoveries, where materials are engineered or altered so that they perform a particular function. They react independently, which is why they are known as ‘smart’, and some appear to have a ‘memory’: for example, deforming and returning to their original shape/structure under certain conditions, such as heat from an electrical current (shape memory alloys and the effect of heat on shape memory polymers). Modern materials also include those manufactured by making changes to the structure at molecular level or using nanoparticles, such as the super strong graphene or hydrophobic surfaces that repel water. Some smart and modern materials are inspired by nature; this is called biomimicry.
Smart and modern materials have numerous applications in health and medicine. A ‘stent’ is a small mesh tube, made from a shape memory alloy, which is inserted into damaged blood vessels to strengthen or keep them from collapsing. The stent is inserted cold and expands into the desired size with the patient’s body heat.
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