(755b) Nanostructured Shape Memory Polymers Triggered By Unconventional Stimuli

Smart shape memory polymers (SMPs) can memorize and recover their permanent shape in response to an external stimulus, such as heat, light, and solvent. They have been extensively exploited for a wide spectrum of applications ranging from biomedical devices to aerospace morphing structures. However, most of the existing SMPs are thermoresponsive and their performance is hindered by slow response speed, heat-demanding programming and recovery steps. Here, by integrating scientific principles drawn from two disparate fields that do not typically intersect - the fast-growing photonic crystal and SMP technologies, we demonstrate a new type of SMP that enables unusual "cold" programming and instantaneous shape recovery triggered by a large variety of unconventional stimuli, such as static pressure, numerous vapors and liquids, lateral stress, and ultrasonic wave. The active components of the new SMPs are thin macroporous photonic crystal layers (only a few mm thick) which are fabricated by using self-assembled, 3-D highly ordered colloidal crystals as structural templates. This nanoscopic thin-film configuration renders orders of magnitude faster response speed than bulky SMP samples in traditional applications. Additionally, these nanostructured multi-stimuli-responsive materials differ greatly from existing bulk SMPs as they enable striking chromogenic effects and all-room-temperature operations for the entire shape memory cycle, promising for many applications ranging from reusable chromogenic vapor sensors to reconfigurable nanooptical devices. Moreover, this interdisciplinary integration provides a simple and sensitive optical technique for investigating the intriguing shape memory effects at nanoscale.