What if a single sustainable material could be made rigid in one area, flexible in another and strong somewhere else—without joining different materials together? Researchers at the Institute for Bioengineering of Catalonia (IBEC) have developed a new approach that could make this possible. By adding tiny amounts of different metal ions to chitosan, the team found a way to locally control how stiff, strong and flexible the material becomes while keeping the same basic polymer. The research, published in the Journal of Materials Chemistry A , takes inspiration from one of nature’s most efficient designs: the insect exoskeleton. Learning from insect exoskeletons Modern products often depend on several different materials. A bottle may have a rigid body and a flexible cap or seal. Electronic devices can contain hard casings, soft protective layers and flexible components. Although combining materials can provide useful properties, it creates a major problem when the product reaches t...