(716f) Reconfigurable Self-Assembled Photonic Crystals Enabled By Novel Stimuli-Responsive Shape Memory Polymers

Photonic crystals may hold the key to continued progress towards all-optical integrated circuits and quantum information processing. Shape memory polymers (SMPs), which can memorize and recover their permanent shapes upon application of an external stimulus (e.g., heat and light), provide an unique opportunity to achieve smart, reconfigurable photonic crystals with bistable states.  Unfortunately, most of the currently available SMPs are thermoresponsive and they suffer from slow response speed and heat-demanding programming and recovery steps.  Although pressure is an easily adjustable process variable like temperature, pressure-responsive SMPs are largely unexplored. By integrating scientific principles drawn from two disparate fields that do not typically intersect - the fast-growing photonic crystal and SMP technologies, we have recently developed a new type of SMP that enables unusual "cold" programming and instantaneous shape recovery triggered by applying an external pressure or exposing to an organic vapor (e.g., acetone) at ambient conditions. This unique integration has not only led to the discovery of the new pressure- and vapor-responsive SMPs, it also provides a simple and sensitive optical technique for investigating the intriguing shape memory effects at nanoscale. Simultaneously, these novel stimuli-responsive SMPs empower smart and reconfigurable nanooptical devices, such as rewritable photonic crystal circuits and tunable antireflection coatings. Systematic mechanical and thermomechanical experiments have also been conducted to elucidate the basic shape memory mechanisms of this new type of SMP.