Search

Flexible self‐healing thermal management devices are increasingly in demand due to their high flexibility, low driving voltage, and excellent stability of thermal property. In this paper, the design of mechanochromic self‐healing thermal management devices is reported based on photonic vitrimer through self‐healing dynamic covalent bond. A series of new photonic vitrimers i first prepared by dynamic disulfide covalent bond and PS@SiO2 photonic crystals. The resulting photonic vitrimer exhibits bright structural colors, large tensile strain (>1000%), high mechanical strength (>10 MPa) and self‐healing ability (>95% efficiency). More importantly, the structural color remains constant after 10000 stretching/releasing cycles, demonstrating excellent mechanical stability, creep‐resistance, and durability. Taking advantage of the above features, a novel mechanochromic flexible wireless thermal management (MFW) device is developed by semi‐embedding the photonic vitrimer in a thermally conductive carbon nanotube film and then integrating it with a Bluetooth module and a control chip. Interestingly, the MFW device exhibits mechanochromic property, fast thermal response, low driving voltage (103 °C, at 3 V), and precise temperature control. Notably, the device even remains electrothermal performance (105 °C) after self‐healing. This work provides new insight into the self‐healing photonic materials, and the device shows promising applications in wearable electronics, vitro physiotherapy, and personal heating. [ABSTRACT FROM AUTHOR]

The growing interest in mimicry of biological skins greatly promotes the birth of high‐performance artificial skins. Chameleon skins can actively transform environmental information into bioelectrical and color‐change signals simultaneously through manipulating ion transduction and photonic nanostructures. Here, inspired by chameleon skins, a novel biomimetic chromotropic photonic‐ionic skin (PI‐skin) capable of outputting synergistic electrical and optical signals under strain with robust adhesion, stability, and resilience is ingeniously constructed. The PI‐skin exhibits sensitive structural color change synchronized with electrical response via adjusting the lattice spacing of the photonic crystal (mechanochromic sensitivity: 1.89 nm per %, Δλ > 150 nm). Notably, the polyzwitterionic network provides abundant electrostatic interactions, endowing the PI‐skin with excellent adhesion, environmental tolerance, and outstanding mechanical stability (>10 000 continuous cycles). Meanwhile, the high loading of ionic liquid (IL) weakens the electrostatic interaction between the polyzwitterionic molecular chains, leading to high resilience. The PI‐skin is finally applied to construct a visually interactive wearable device, realizing precise human motion monitoring, remote communication, and visual localization of pressure distribution. This work not only expands design ideas for the construction of advanced biomimetic I‐skins but also provides a general optical platform for high‐level visual interactive devices and smart wearable electronics. [ABSTRACT FROM AUTHOR]

The integration of invisible photonic patterns into specific micro/nanostructures provides a new way to construct stimuli‐responsive optical anti‐counterfeiting devices. Herein, an innovative strategy for constructing highly invisible patterns in the solvent‐responsive double‐inverse‐opal (DIO) films by the thermal treatment is proposed. The masked area retains the responsive DIO structure, but the exposed area loses the periodic ordered array, which results in different optical responses of the pattern and background to the solvent. Due to the special structure, the scattering effect derived from the randomly distributed polystyrene microspheres within the pores of the inverse‐opal backbone in both the masked area and the exposed area makes the resultant film sample present a pale color, and the encrypted pattern is highly invisible in normal conditions. Interestingly, the hidden pattern can be quickly revealed by ethanol response, showing a large color contrast. Furthermore, reversible bilayer DIO films with multiple hidden patterns for advanced anti‐counterfeiting materials are prepared. Importantly, the as‐prepared film sample can reveal different patterns on the front and back sides in decryption, and simultaneously the overlapping part of the patterns can achieve color mixing based on the bilayer structure, thereby showing great potential in information encryption and anti‐counterfeiting fields. [ABSTRACT FROM AUTHOR]

Janus structure offers materials unique functionalities which are difficult to achieve otherwise with isotropic counterpart, opening up new avenues in diverse application fields. Here, a series of novel photonic Janus carbon fibers (PJCFs) with structural color gradient and excellent mechanical stability are reported by introducing 1D photonic layers with a gradient of periodicity. By virtue of the unique photonic architecture, the PJCFs exhibit a multiple and continuous variation of structural color (i.e., structural color gradient) in a full spectrum. By controlling the thickness of periodic layer, a series of PJCFs with vivid and tunable structural colors ranging from blue, green, orange, to violet‐red can be obtained. Furthermore, their gradient structural colors remain constant after reciprocating rubbing and laundering, showing outstanding mechanical robustness. Notably, benefiting from the inherent electrothermal property and flexibility of CFs, the PJCFs display stable Joule heating performance even under deformation. As proof‐of‐concept, the PJCFs are further integrated with wireless transmission system to construct a multicolored, wirelessly controlled thermal management device, realizing remote and precise temperature manipulation via Bluetooth. This work provides not only a new platform for achieving distinct structural color gradient of CFs, but also a promising strategy toward next‐generation multicolored personal healthcare devices. [ABSTRACT FROM AUTHOR]

Vitrimers, with their unique dynamic covalent bonds, possess attractive self‐healability and mechanical robustness, providing an intriguing opportunity to construct functional soft materials. However, their potential for function recovery, especially optical function, is underexplored. Harnessing the synergistic effect of photonic crystals and vitrimers, a novel photonic vitrimer with light regulating and self‐healing capabilities is presented. The resulting photonic vitrimer exhibits a large tensile strain (>1000%), high toughness (21.2 kJ m−3), bright structural color, and mechanochromism. Notably, the structural color remains constant even after 10 000 stretching/releasing cycles, showing superior mechanical stability, creep‐resistance, and excellent durability. More importantly, the exchange of dynamic covalent bonds imparts the photonic vitrimer with a self‐healing ability (>95% efficiency), enabling the recovery of its optical function. Benefiting from the above merits, the photonic vitrimer has been successfully used as a sensor for human motion detection, which demonstrates visualized interactive sensibility even after self‐repairing. This material design provides a general strategy for optical functionalization of vitrimers. The photonic vitrimer elastomers present great potential as resilient functional soft materials for diverse flexible devices and a novel optical platform for soft robotics, smart wearable devices, and human‐machine interaction. [ABSTRACT FROM AUTHOR]

Mechanical nondiscoloring and antistretching photonic crystal (PC) films, especially those with stable structure colors during deformation, have great potential applications in wearable display devices, decoration, and packaging. Here, PC films with antistretching and invariant structural colors during deformation were prepared, by combining Zn2+ coordinated elastic material and hydroxypropyl methylcellulose (HPMC) with polystyrene@silica (PS@SiO2) colloidal crystals. The PC films release energy by forming local fractures at a microscopic level during the straining process but the lattice spacing and effective refractive index of the local array do not change. According to the Bragg law, the structure color remains unchanged. The introduction of HPMC gave the PC films excellent tensile properties, and the maximum tensile strength reached 10 MPa. And after 100 times of stretching, bending and compression cycles, the structural color remained unchanged. [ABSTRACT FROM AUTHOR]

Single-material flexible actuators that can produce non-uniform deformation in response to external stimuli have attracted considerable interests due to their facile fabrication process and excellent actuation behavior. However, the recognition of actuation state with easily perceived and detectable signal is still a challenge. In this paper, we report an actuator behavior of single-material inverse opal photonic crystal films, which are in response to a variety of solvents based on swelling/de-swelling process. The actuator exhibits improved responsiveness due to the enhanced mass transport of solvent molecules in periodic inverse opal with macroporous structure. Especially, peaks in reflective spectra and corresponding structure colors are obviously changed, providing a simple and effective optical technology for optical recognition of micro-locomotion. Based on the above characteristics, we demonstrate the potential applications of this photonic crystal actuator as solvent-driven gripper, walking device and rolling motor, showing great promise in advanced soft robot for many important intelligent areas. [ABSTRACT FROM AUTHOR]

In this study, a novel flexible and robust dual-network supramolecular elastic film with solvent resistance and brilliant structural colors was prepared by combining a Zn2+-crosslinked supramolecular elastic film with polystyrene@silica (PS@SiO2) colloidal crystals. This structurally colored supramolecular elastic material consisted of a covalent support network formed by three different monomers and a Zn2+-crosslinked polyacrylic acid (PAA) coordination network, which provided high mechanical strength and flexibility. The tensile and compression stress of this structural color reached 3.26 MPa at a strain of 187% and a pressure of 300 N. The reflectance wavelength of the structural color film remained unchanged after loading–unloading cycles and compression cycles. The structural color film could be bent and unfolded without heating or the application of an external stimulus. Moreover, the structural color film exhibited resistance to solvents in saturated organic vapors and remained color invariant. [ABSTRACT FROM AUTHOR]

• Photonic-ionic skin (PI-skin) is constructed with the fluorine-rich ionogel crosslinked by hindered urea bonds. • PI-skin exhibits strain-induced electrical/optical dual response synchronously. • PI-skin displays underwater stabilization, self-healing performance, and high resilience. • PI-skin demonstrates applications for dual-signal underwater sensing and wireless dual-encrypted information transmission. Bioinspired photonic-ionic skins (PI-skins) possessing multiple signals considerably promote the development of soft ionoelectronics owing to the fascinating interactive sensing capabilities. Unfortunately, swelling and leakage in aqueous environments are significantly detrimental to the stability and durability of underwater sensing. Herein, a novel PI-skin with waterproof, self-healing, and highly resilient properties is ingeniously fabricated via integrating the photonic array and dynamically covalently crosslinking fluorine-rich ionogel. Benefiting from the strain-modulated nanostructure and ionic conduction, the PI-skin achieves unique dual-signal sensing capability with sensitive mechanochromic performance and synchronous electrical response. Furthermore, the synergistic water repellency of the trifluoromethyl on the skeleton and the long alkyl chain modified hydrophobic ionic liquid (IL) inhibit swelling and leakage, significantly enhancing underwater stability. Notably, the exchangeable hindered urea bonds (HUBs) were judiciously introduced to construct a stable dynamically covalently crosslinking network, achieving efficient self-healing and high resilience simultaneously. The PI-skin with excellent adhesion and durability demonstrates the application potential in dual-signal underwater sensing and wireless information transmission. This work offers innovative design inspirations for the advancement of multifunctional artificial skins, intelligent interactive devices, and high-performance wearable iontronics. [ABSTRACT FROM AUTHOR]

• Photonic-ionic skin (PI-skin) is constructed by dynamic covalent crosslinked ionogel. • PI-skin exhibits electro-optical dual response under stretched/compressed. • PI-skin demonstrates robust resilience and high-efficiency self-healing. • A novel interactive human–machine interface is demonstrated based on the PI-skin. Advanced skin systems realize perception and interaction with the environment through synergistic electrical and color signals generated by transmitting ions and manipulating photonic structures. Here, inspired by chameleon skins, a novel self-healing and resilient photonic-ionic skin (PI-skin) with electro-optical dual response is ingeniously constructed integrating the ordered micro-nano array and the dynamically covalently cross-linked ionogel. The elaborately designed polycation network with weak inter-chain interactions can promote the uniform distribution of high-content low-viscosity ionic liquid (IL), effectively eliminating energy dissipation and resulting in high resilience. Dynamic acylhydrazone bonds are served as reversible chemical crosslinking to realize high-efficiency self-healing and further enhance resilience. Notably, the artificially manipulated transition of the photonic array from dense packing to non-dense packing endows sensitive chromotropic properties synchronized with electrical response under stretched (Δλ > 130 nm) and compressed (Δλ > 160 nm). Furthermore, by harnessing the correspondence between electrical and optical signals, the control of optical signals over electrical signals is achieved for inputting complex coded information and constructing interactive human–machine interfaces. This work not only inspires the design and construction of high-level artificial skins but also stimulates the development of visual interactive devices and smart electronic/ionic products. [ABSTRACT FROM AUTHOR]

[Display omitted] • Antibacterial photonic gel is firstly developed by hierarchical self-assembly strategy. • Photonic-ionic skin kills Gram-positive bacteria and fungus with > 99.9% antibacterial rate. • The skin exhibits electrical/optical reporting even in various harsh environments. • The skin displays different dual-signals to identify strain, pressure and temperature. • The skin can be used as wirelessly wearable device for remote visual/digital feedback. Squid skins can actively transduce complex environmental information into bioelectrical and color-change signals. Here, inspired by squid skins, we present a novel photonic-ionic skin (PIskin) capable of outputting electrical/optical signals synergistically, featuring anti-freezing, drying-tolerance and antibacterial abilities. The PIskin was developed by hierarchical self-assembly strategy of antibacterial glycerol monolaurate (GML) in a poly-(diacetone acrylamide- co -acrylamide) gel matrix, followed by solvent displacement method of introducing PEG200 and ionic liquids (ILs). It demonstrates dual-signal reporting and intelligent identification capabilities for strain, pressure and temperature, using mechanochromism, ionic mechanotransduction and ionic thermosensitivity respectively. Furthermore, PIskin possesses long-term stability (>20 d) in ambient air and maintains high stretchablility, bright structural color and outstanding conductivity even stay at extreme conditions (-20 °C–80 °C). Notably, the GML and ILs endow the PIskin with significant antibacterial ability for Gram-positive bacteria and fungus (>99.9% antibacterial rate). Based on these remarkable capabilities, the PIskin is integrated with Bluetooth transmission system to build an interactive wearable sensor for real-time remote digital/visual feedback of joint motion and tactile sensation (such as temperature and pressure), realizing wirelessly visual multi-sensing. This investigation provides a general and enlightening design strategy for constructing high-performance interactive skins based on photonic gels, and opens up more possibilities for meeting specific requirements in practical applications of wearable flexible devices, soft intelligent robots, human–machine interfaces and so on. [ABSTRACT FROM AUTHOR]

[Display omitted] • Large-area water rewriteable double-inverse opal film is prepared. • Ultrafast response time and robust water writing capability are obtained. • The retention time of written marks can be controlled. • Spatio-temporal colorful patterns are constructed. • Information security materials with multistate switching are designed. Photonic paper, as a crucial branch of the research of structural color materials, has attracted considerable attention. Herein, innovative large-area water rewriteable double-inverse opal (WRDIO) film with ultrafast response time (∼0.8 s) and robust writing capability is fabricated by introducing polyacrylamide gel into the double-inverse opal. The hydrophilic nature of the polyacrylamide gel can induce water to quickly penetrate the internal pores of the inverted opal backbone. Simultaneously, the randomly distributed polystyrene microspheres within the pores become ordered under the action of liquid buoyancy, which eliminates the scattering disturbance and makes the film switch to the structural color state. Importantly, the as-prepared WRDIO film can be erased and rewritten over 500 cycles without significantly reducing the color quality. Besides, the retention time of the written marks can be controlled by writing using water pens with different water outputs. Interestingly, responsive spatio-temporal colorful patterns could be achieved based on the different volatilities of written marks. Furthermore, advanced optical anti-counterfeiting material with multistate switching for information security is prepared based on controlled wettability. Given these superior properties, this novel WRDIO film provides a new solution for future applications of rewriteable paper. [ABSTRACT FROM AUTHOR]

[Display omitted] • Double-inverse-opal photonic crystals are used to construct water-response films. • Rapidly responsive time and brilliant structural color are obtained. • The response mechanism achieved by water stimuli is demonstrated. • A highly invisible pattern revealed by water response is designed. • A facile and visual sensor to detect water in an ethanol-rich mixture is proposed. The construction of novel photonic structures renders the possibility for creating stimuli-responsive functional materials. Herein, innovative water-response double-inverse opal (WRDIO) films with fast response time and brilliant structural color are first fabricated by introducing polystyrene microspheres into the inverse-opal backbone. The deprotonation of carboxyl groups generated by sodium carbonate treatment in the inverse-opal backbone inhibits the formation of hydrogen bonds among the polymer chains and the exposed carboxyl anions lead to hydrophilicity, which is conducive to the penetration of water into the internal pores. The response is achieved by inducing the polystyrene spheres within the pores from random distribution to the ordered assembly in the water environment, thus eliminating the scattering disturbance and developing bright structural color. Meanwhile, WRDIO film with a highly invisible pattern revealed by water stimuli is prepared. Furthermore, the content of carboxylic anions in the polymer affects the optical behavior and the increased osmotic pressure caused by high-proportioned carboxylic anions makes the WRDIO film swelled rapidly by water, whereas ethanol cannot. The broad-spectrum shifting (≈92 nm) depends on the composition of the ethanol-water mixture. Thus, the rapidly water-response and easy-to-use film materials with brilliant structural color exhibit potential applications in user-interactive anti-counterfeiting and sensors. [ABSTRACT FROM AUTHOR]

• A novel interactively mechanochromic electronic textile sensor has firstly been proposed. • The sensor demonstrates negative electrical response and simultaneous mechanochromism upon stretching. • The sensor exhibits rapid and durable electrical/optical response. • The sensor shows bright structural colors, enhanced toughness and excellent mechanical resilience. • The sensor can be used as interactive wearable devices for monitoring various human joint movements. Textile-based electronic devices are significant components of emerging wearable electronics. However, the current textile-based electronics are limited by single electrical signal input/output, and unable to be visualized directly by human eyes, restricting their diverse applications in visualized human-interactive electronics. Here, we develop a series of novel interactively mechanochromic electronic textile (MET) sensors for visualized stretchable electronics. The MET sensors are based on the ingenious coupling of new supramolecular photonic elastomers (PEs) with hierarchical-fiber-structured conductive polyester textiles (CPTs). Benefiting from their semi-embedded structures, the MET sensors demonstrate not only distinct negative electrical response but also simultaneous mechanochromic capability upon stretching, via reconstructing conductive paths and adjusting the lattice spacing of the photonic crystals. Notably, the MET sensors exhibit bright structural colors, enhanced toughness (35.6 kJ m−3), excellent mechanical resilience, fast optical/electrical response (≈0.30 s) and recovery speed (≈0.22 s). Most importantly, the structural colors and electrical responses of the MET sensors remain constant even after 30,000 stretching/releasing cycles, showing outstanding mechanical stability, reliability, and excellent durability. Based on these merits, the MET sensors are used as visually interactive wearable devices for monitoring human joint movements in real time. This research provides a general platform for achieving visualized interaction of the electronic textiles, which shows great prospects in wearable devices, human–machine interfaces, and soft robotics. [ABSTRACT FROM AUTHOR]

Mechanical discoloration and non-discoloration materials have received intensive interest and have been strongly developed over the past few years for anti-counterfeiting, sensing, and packaging. However, the fabrication of mechanical response materials with both angle-dependent and angle-independent structural colors remains challenges. Large-area mechanochromic bilayer polydimethylsiloxane (PDMS) film with both angle-dependent and angle-independent structural colors have been prepared by using bottom-up bar-coating. The long-range disordered and short-range ordered polystyrene (PS) nanoarrays give the bilayer film angle-independent structural color. Meanwhile, the surface wrinkling triggered by stretching generates angle-dependent structural color. Moreover, PS nanoarray cracks and surface wrinkles caused by tensile increase the scattering effect of the bilayer film and decrease the transmittance of the light. Importantly, pressure-induced surface structure rearrangements can deprive wrinkling behavior. The pressure-encoded invisible complex information can be displayed reversibly by stretching. It has potential application value in complex information coding, display, and smart window. [Display omitted] • The bilayer large-area structure color film can be easily and quickly prepared by using bottom-up bar-coating. • The rigid PS nanoarrays show non-discoloration and the wrinkles display discoloration during the straining process. • The bilayer film has both angle-dependent and angle-independent structural colors. • We confirmed that pressure-induced surface structure rearrangements can deprive wrinkling behavior. • PS nanoarray cracks and wrinkles caused by tensile increase the scattering effect of the bilayer film. [ABSTRACT FROM AUTHOR]

Artificially constructed noniridescent structural colors originating from the coherent scattering of visible light have attracted widespread interest and show great potential in color-related fields. In this paper, the vivid noniridescent structural colors on white fabric with robust structural stability are fabricated by a fast screen printing technique and it is easy to achieve large-scale production and multi-color pattern output with a multistep printing process. The obtained noniridescent structural colors on various substrates have high color visibility. Meanwhile, polyacrylate (PA) as the waterborne adhesive in the printing paste system greatly enhances structural stability, which is subsequently confirmed by laundering and rubbing tests. The innovative and environmentally friendly dyeing technology exhibits great potential applications in textile coloring and other color-related fields. • A green coloring method based on fast screen printing technology. • Large-scale production and multi-color pattern output. • The great potential of industrial production. [ABSTRACT FROM AUTHOR]