Bioinspired Water‐Vapor‐Responsive Organic/Inorganic Hybrid One‐Dimensional Photonic Crystals with Tunable Full‐Color Stop Band

Abstract

Bioinspired organic/inorganic hybrid one-dimensional photonic crystals (1DPCs) are prepared by alternating thin fi lms of titania and poly(2-hydroxyethyl methacrylate-co-glycidyl methacrylate) (PHEMA-co-PGMA) by spincoating, which is a simple, reproducible, and low-cost approach. Their optical properties are tuned by changing the number of layers, incident angles, and the thickness of the layers. The color of the 1DPCs can span the entire visible spectral range when the period or the refractive index is changed. Due to the response of PHEMA-co-PGMA to water vapor, the 1DPCs possess fast water-vapor responsiveness and reversible full-color switching. The color of the 1DPCs varies from blue to green, yellow, orange, and red under differing humidities, covering the whole visible range. At high water-vapor concentrations, the color of the 1DPCs rapidly changes from blue to red and comes back to the original state immediately after exposure to air; this behaviour is like that of some animals in nature. The repeatability of the reversible response of the 1DPCs to water vapor is perfect and can be repeated more than 100 times. The as-prepared 1DPCs successfully combine structural color and water-vapor sensitivity, which is promising for use as materials for colorful detection across the full color range.

Touchless Optical Finger Motion Tracking Based on 2D Nanosheets with Giant Moisture Responsiveness

“…[3][4][5] Besides, these periodic structures are capable of tuning the displayed color while keeping their transparency, thus opening up the possibility to fabricate smart windows with tunable color as a function of the environmental conditions. Although porous BSs have been extensively used to detect organic vapors and humidity through RI changes induced by infi ltration with analytes, [6][7][8][9][10][11][12] the observed shifts in the Bragg peak (BP) are rarely larger than a few tens of nanometers, and typically well below 100 nm, [9][10][11]13 ] which limits the resolution in terms of humidity sensing.…”

Inkjet‐Printable Amphiphilic Polydiacetylene Precursor for Hydrochromic Imaging on Paper

“…[3][4][5][6] Hydrochromic substances bearing amino-coupled fl uorophores also have been employed to determine the presence of water in organic solvents. [ 13,14 ] Sensors of this type emit only weak fl uorescence owing to the occurrence of facile quenching caused by photoinduced electron transfer (PET) from the amine moiety to the fl uorophore.…”

Characterization and Biomimcry of Avian Nanostructured Tissues

“…However, no evidence has directly supported this assumption. 7,9,11 Here, we were able to monitor the thickness expansion of SMNP film under different humid conditions using environmental SEM (ESEM). We measured the cross-sections of a SMNP film equilibrated at certain water vapor pressure at room temperature (24℃) and calculated the relative humidity by dividing the water pressure by saturated water pressure (22.31 Torr at 24℃).…”

“…Most 1D photonic crystal structures contain an inorganic/organic hybrid multilayer because the inorganic material, such as titania, offers a higher refractive index than pure organic materials. [7][8][9] Most humidity induced dynamic colors in opal or inverse opal structures are made with hydrogels that absorb moisture as humidity increases, changing the periodic domain spacing and effective refractive index of the material. [10][11][12] Replacing hydrogels with natural materials like silk-fibroin only causes as small color change as 20 nm wavelength shift when increasing relative humidity from 30% to 80%.…”