Reconfigurable Photonic Crystals Enabled by Multistimuli-Responsive Shape Memory Polymers Possessing Room Temperature Shape Processability

Abstract

Traditional shape memory polymers (SMPs) are mostly thermoresponsive, and their applications in nano-optics are hindered by heat-demanding programming and recovery processes. By integrating a polyurethane-based shape memory copolymer with templating nanofabrication, reconfigurable/rewritable macroporous photonic crystals have been demonstrated. This SMP coupled with the unique macroporous structure enables unusual all-room-temperature shape memory cycles. "Cold" programming involving microscopic order-disorder transitions of the templated macropores is achieved by mechanically deforming the macroporous SMP membranes. The rapid recovery of the permanent, highly ordered photonic crystal structure from the temporary, disordered configuration can be triggered by multiple stimuli including a large variety of vapors and solvents, heat, and microwave radiation. Importantly, the striking chromogenic effects associated with these athermal and thermal processes render a sensitive and noninvasive optical methodology for quantitatively characterizing the intriguing nanoscopic shape memory effects. Some critical parameters/mechanisms that could significantly affect the final performance of SMP-based reconfigurable photonic crystals including strain recovery ratio, dynamics and reversibility of shape recovery, as well as capillary condensation of vapors in macropores, which play a crucial role in vapor-triggered recovery, can be evaluated using this new optical technology.

Programmable Macroporous Photonic Crystals Enabled by Swelling‐Induced All‐Room‐Temperature Shape Memory Effects

“…In addition, the response speeds (for both programming and recovery steps) of thermoresponsive SMPs are controlled by the heat transfer rate through the bulky samples, though most polymers are not good heat conductors. [34,59] We have developed a series of SMPs, which are copolymers of ethoxylated acrylates, to enable unconventional all-roomtemperature SM effects. [45,46] Novel SMPs that enable nontraditional, all-room-temperature shape memory (SM) cycles could facilitate to resolve the major drawbacks of thermoresponsive SMPs in developing active, programmable nanooptics.…”

“…[45,46] Novel SMPs that enable nontraditional, all-room-temperature shape memory (SM) cycles could facilitate to resolve the major drawbacks of thermoresponsive SMPs in developing active, programmable nanooptics. [59] Herein, by conducting extensive experimental and theoretical investigations on swelling-induced plasticizing effects during both SM programming and recovery steps, we have demonstrated reversible and reproducible all-room-temperature SM cycles using a new polyurethane-co-tripropylene glycol diacrylate (PU-co-TPGDA) copolymer with much improved thermomechanical/mechanical properties (T g ≈87 °C, E ≈3 GPa for a solid membrane and ≈0.47 GPa for a macroporous copolymer). [47][48][49][50][51][52] The convenient preparation of temporary shape is usually achieved by directly stretching or compressing the SMPs under ambient conditions through "reversible plasticity shape memory" or strain-induced polymer crystallization.…”

Rapid 3D Printing Magnetically Active Microstructures with High Solid Loading

“…Combining two monomers exhibiting different viscosities as the base materials allowed us to widely tune the viscosities of the magnetic resin. The primary monomers being used consisted of CN982A75 (Sartomer Inc., viscosity of 1115 cps) monomer, which is an aliphatic polyester‐/polyether‐based urethane diacrylate oligomer blended with 25% tripropylene glycol diacrylate (SR306; Sartomer Inc.) . The secondary monomer was the poly(ethylene glycol) diacrylate (PEGDA; average Mn 700) (Sigma‐Aldrich Inc.) with relatively low viscosity of 55 cps .…”

New Encryption Strategy of Photonic Crystals with Bilayer Inverse Heterostructure Guided from Transparency Response

“…Fortunately, these transitions are possible obtained with conditional responses. Immersion of the sample in a particular fluid induced the disappearance of the reflected color and the display of a unique spatial pattern dictated by infiltration (due to refractive indexes matching or 3D structure collapsing) . That is to say, the transparent transition of the film can be achieved by wetting with solvents with low surface tension (for example, ethanol) .…”