Capillarity-induced folds fuel extreme shape changes in thin wicked membranes

Reserving the right to stretch Retractable antennae or certain spider silks can stretch well beyond their apparent length because they have a reserve of material that lets them expand and contract over much longer distances. Grandgeorge et al. made nonwoven fibrous membranes by electrospinning a block copolymer with varying ratios of two components. They infused these membranes with a liquid that let the fibers buckle and fold without changing the apparent surface area. When the membranes were stretched, this material could unbuckle and slide along the membrane surface, allowing it to extend without breakage. Science , this issue p. 296