Shape Reconfiguration of a Biomimetic Elastic Membrane with a Switchable Janus Structure

A method for the fabrication of a biomimetic Janus composite membrane is reported here. This approach is based on a membrane with a vertical gradient crosslinking degree, which is achieved through UV light–induced dimerization of anthracene grafted on poly(styrene-block-butadiene-block-styrene) chains in the presence of carbon nanotubes. UV light penetration is controlled by the accretion of carbon nanotubes to ultimately tailor the heterogeneous crosslinking degree in thickness. This kind of Janus structure is applied here for shape actuation. Here, solvent or shape memory effect–induced shape morphing is obtained via the heterogeneous swelling (deswelling) abilities of, or internal stress from, the Janus structure. By tailoring the UV light irradiation time, the irradiated region and the prestrain, sophisticated and multiple types of shape morphing are programed. In addition, this type of Janus structure can shift back to the homogeneous structure via dedimerization of the anthracene dimers upon thermal treatment, which provides extensive freedom for the design of smart responsive actuators.