Advanced optical materials with rational designs and tunable light transmission have been drawing increasing interest due to their great potential in energy‐efficient buildings and on‐demand optical devices. Mechanoresponsive smart windows (SWs) can modulate light transmittance by mechanical actuation, showing high energy efficiency, low cost, and chemical stability. However, current research mainly focuses on tensile strain‐responsive SWs that typically require a large strain to achieve optical transparency switching‐which causes great inconvenience to practical application and fatigue damage to matrix materials. Herein, a novel shear‐responsive SW with high strain sensitivity is fabricated by vertically fixing a Fe3O4@SiO2 nanochains (NCs) array in an elastic polyacrylamide matrix. The flexible SW exhibits optically transparent with all NCs standing vertically to the SW surface at initial relaxation state, which enables a good shielding effect, with NCs tilting along the shearing direction as the strain applied. Critically, a rather small shear displacement (1.5 mm) applied on the surface of SW gives rise to tunable optical states varying from the transparency state of 65% transmittance to the opaque state of 10%. The as‐prepared SW with novel tuning modulation, high shear strain sensitivity, and optical angle‐dependence holds promising potential in smart windows, optical switches, anti‐voyeurism, and etc.
Bright structural colors with an angular-independent character are in increasing demand in many fields such as pigments, buildings, sensors, color displays, and anti-counterfeiting labels. However, the structural colors produced by amorphous colloidal assemblies with low refractive index contrast or without black additives often exhibit low color visibility and low liquid-bleaching resistibility. Herein, large-scale and angleindependent structural colors were constructed from Fe 3 O 4 @SiO 2 colloidal quasiamorphous arrays (QAAs) prepared through a rapid "spraying" process. Due to the high-refractive-index and intrinsic black nature of Fe 3 O 4 , the coatings exhibit high brightness of structural colors even on white substrates under ambient lighting conditions. Moreover, as-obtained structural colors possess the ability of antiliquid bleaching and solvent-responsiveness. More importantly, flexible Fe 3 O 4 @SiO 2 /PDMS photonic paper can be fabricated by permeation of PDMS into the voids of Fe 3 O 4 @SiO 2 colloidal QAAs. This QAAs-based photonic paper shows the ability to infuse silicone oils into its structure, locally swelling it and changing the reflected color. In turn, the resulting colored patterns can be easily erased by applying ethanol or low molecular weight silicone oils. The as-prepared photonic paper exhibits excellent durability and is rewritable at least 50 times without any significant changes in performance. Compared with the traditional long-range ordered photonic crystals, the rapidly prepared QAAs-based photonic coatings have unique advantages in the applications of permanents, color coatings, color printing, liquid colorimetric sensors, rewritable photonic paper, etc. because of the good structural color performance and are suitable for rapid and large-area preparation.
Herein, we demonstrate a new information encryption strategy based on multilayer quasi-amorphous photonic structures (QAPS) composed of alternating arrangements of high and low refractive index materials. The new designs are...
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