Colorful Berry-Inspired Fibers

Fibers that change color when stretched could lead to the design of smart fabrics that register properties such as muscle strain. Peter Vukusic of the University of Exeter, in England, Mathias Kolle of Harvard University, and colleagues say they were inspired to create the fibers by the bright blue-green iridescent seed coating of the “bastard hogberry” fruit, Margaritaria nobilis, which grows in Central and South American rain forests. Cylindrical cells in the seed coat are stacked in repeating layers, which causes interference of impinging light and reflectance of blue light. This same phenomenon produces color on soap bubbles. To mimic that architecture, the researchers wrapped multiple sheets of a bilayered material—a cross-linked polydimethylsiloxane film on top of a polystyrene-polyisoprene-polystyrene triblock copolymer—around a 15-μm-diameter cylindrical glass core. After the core is removed, the fibers can be stretched to produce any color (Adv. Mater., DOI: 10.1002/adma.201203529).