Rapid Responsive Mechanochromic Photonic Pigments with Alternating Glassy-Rubbery Concentric Lamellar Nanostructures

Abstract

Photonic pigment particles prepared via self-assembly have been suffering from their poor mechanical performances; i.e., they can easily be damaged and lose structural color under a compression force. This greatly limits their uses as mechanochromic pigments. Here, a nanoscale concentric lamellar structure of alternating glassy-rubbery microdomains is successfully created within photonic microparticles through a confined self-assembly and photo-cross-linking strategy. The glassy domain is composed of polystyrene, and cross-linked bottlebrush polydimethylsiloxane served as the supersoft elastic domain. The obtained photonic structure not only shows large deformation and visible color changes under a loaded compression force but also rapidly recovers to its original state in less than 1 s (∼0.16 s) upon unloading. Continuously loading-unloading micro compression test indicates that no obvious damage can be identified after 250 cycles, indicating the high durability of the pigments against deformation. These pigments with different reflected colors are simply obtained using bottlebrush block copolymer formulations with tunable weight percentages of polymer additives. The mechanical robust photonic pigments may be useful in many important applications.

Fast Self‐Assembly of Photonic Crystal Hydrogel for Wearable Strain and Temperature Sensor

“…[12] Benefiting from structure colors, numerous visual devices, such as actuators, [14] flexible electronics, [15,16] strain sensors, [17][18][19] and other sensors [20,21] have been developed to monitor human motions, [15,16,22] temperature, [23,24] pH, [24] chemical sensing, [25][26][27] and cell monitoring. [28] At present, structure colors are obtained mainly via two schemes, including top-down fabrications such as direct laser writing, [29] nanoimprinting, [30] solvent release, [31] and bottom-up methods such as the self-assembly of nanoparticles (NPs), [32][33][34][35] cellulose nanocrystals, [36][37][38] block copolymers, [24,39] under capillary force [40,41] or external forces. [42,43] However, the former methods generally require the assistance of sophisticated and expensive equipment, whereas the latter methods generally take a long period from days [14,44] to weeks [24,45,46] with precise environmental control.…”

Janus Photonic Microspheres with Bridged Lamellar Structures via Droplet‐Confined Block Copolymer Co‐Assembly

“…Confined self-assembly of the PS-b-PCL bottlebrush BCP results in an expected lamellar structure as confirmed by scanning electron microscopy (SEM) (Figure S4), which is similar to those reported in previous publications. [12] The domain spacing of the obtained lamellar structure is approximately 52 nm based on SEM analysis, which is not large enough to reflect visible light. For the PEO-b-PCL microspheres obtained through confined self-assembly, a blue color reflection was observed suggesting the formation of an ordered porous structure generated by an OSE mechanism (see Figure 2 for more details).…”

“…Self-assembly of BCPs confined within shrinking emulsion droplets is of great interest as the obtained polymer particles have demonstrated diverse external shapes and internal morphologies. [11] For example, round particles with concentric lamellar structures [12] and ellipsoidal ones [13] with stripped layers were both reported for creating photonic pigments. However, the obtained 1D layered structure shows limited optical properties.…”

Mechano‐Chromic Photonic Crystals with Substrate‐Independent Brilliant Colors for Visual Sensing and Anti‐Counterfeiting Applications

“…Responsive photonic crystals [1,2] have been extensively investigated, which show wide applications in displays, [3][4][5][6][7][8][9] printings, [10][11][12][13][14][15] sensors, [16][17][18][19][20] pigments, [21][22][23] coding-decoding, [24][25][26] and anti-counterfeiting. [27][28][29][30][31][32] Particularly, mechano-chromic photonic crystals [33][34][35][36] (MPCs) exhibit great potential as visual sensors because they can change their colors in response to mechanical forces through shrinkage of their lattice distances. The MPCs can be fabricated based on the packing of particles structures by the co-assembly of silica and silica-PDA particles with the same sizes in poly(ethylene glycol) phenyl ether acrylate (PEGPEA).…”

“…Responsive photonic crystals [ 1,2 ] have been extensively investigated, which show wide applications in displays, [ 3–9 ] printings, [ 10–15 ] sensors, [ 16–20 ] pigments, [ 21–23 ] coding–decoding, [ 24–26 ] and anti‐counterfeiting. [ 27–32 ] Particularly, mechano‐chromic photonic crystals [ 33–36 ] (MPCs) exhibit great potential as visual sensors because they can change their colors in response to mechanical forces through shrinkage of their lattice distances. The MPCs can be fabricated based on the packing of particles into closely [ 37–40 ] and non‐closely [ 7,41–48 ] packed structures.…”