A strategy for making stretchable composite materials with regions of extreme hardness is reported in Nature Communications this week. These composites can be stretched up to 350% in length while the “stiff islands” are unaffected, and they may pave the way for flexible solar cells or wearable electronic devices.
Materials which have regions of varying hardness are desirable but often have weak points where two areas meet. Although nature can produce materials with smooth transitions between hard and soft regions, such as the connections between tendons and bones, it remains difficult to replicate this behaviour in the lab. Andre Studart and his colleagues use a layer-by-layer hierarchical approach to manufacture their material, which contains stiff regions up to 10,000 times harder than the soft, stretchable areas. They show that they are able to mount electronic components on the stiff islands, and their performance is undisturbed by stretching.
The authors suggest that these materials may also be used as artificial biomaterials, such as synthetic cartilage or stronger false teeth.