Pop-Up Liquid Crystals

A soft material made of liquid crystals attached to an elastic polymer goes from a flat sheet to a three-dimensional object in response to heat or a chemical stimulus (Science 2015, DOI: 10.1126/science.1261019). The material, known as a liquid-crystal elastomer (LCE), could find use in aerospace, medicine, or consumer goods, for example, as packaging material or as a tunable antenna. Liquid crystals are materials that have a fluctuating orientation, like a liquid, but are also aligned, like a crystal. Changes in the optical polarization of the liquid block or transmit light, leading to images on liquid-crystal display television sets. To make that shift one that takes shape in three dimensions, a team at the Air Force Research Laboratory, led by Timothy J. White, used light to pattern and align azobenzene-based liquid crystals and then polymerized them into poly(β-amino ester) networks. Depending on the initial patterning, the resulting LCEs can take on various shapes, such as a conical actuator or a molecular hinge.