Inspired by the swelling and deswelling of cephalopod chromatophores and the structural coloration of iridophores, smart optical materials with tunable optical properties through microstructural changes were developed. Monodisperse, thermoresponsive poly(N-isopropylacrylamide-co-methacrylic acid) [P(NIPAM-co-MAA)] colloidal particles were synthesized via free-radical emulsion polymerization. These particles exhibit a reversible temperature-triggered volume phase transition, enabling dynamic optical modulation similar to chromatophore-driven color changes. Upon self-assembly, the particles form ordered colloidal crystals, generating iridophore-like structural colors. These functionalities were applied in two distinct ways: the thermal phase transition enabled smart windows, while the self-assembled photonic structures served as photonic-crystal inks. Our results demonstrate that the PNIPAM-based smart window exhibits a transmittance of approximately 80% in the transparent state. Additionally, the smart window maintains a surface temperature about 2 degrees C lower than conventional glass in a simulated aqueous environment, showcasing its potential for thermal management. Together, these results demonstrate a biomimetic colloidal platform integrating thermoresponsive optical switching with structural coloration for adaptive optical materials.

Smart optical films integrating multiple modalities (fluorescence, phosphorescence, transmission, and scattering) demonstrate significant potential for flexible displays and optical devices. However, fabricating such films remains challenging due to structural design complexity and material synthesis difficulties. Herein, a smart multimodal optical film (SMOF) is fabricated by embedding visible-light-excited phosphorescence nanoparticles (CD-SiO2 NPs) within the polydimethylsiloxane (PDMS) matrix. Notably, the optical properties of SMOF are dynamically tunable through mechanical deformation and visible-light excitation, which effectively circumvent the intrinsic limitations of ultraviolet (UV) excitation. In the released state, the SMOF architecture demonstrates exceptional UV-vis transmittance, which is attributed to the similar refractive index between the PDMS and SiO2 NPs. Concurrently, this film facilitates green-emissive fluorescence and phosphorescence under flashlight excitation, thereby eliminating UV-induced photodegradation. In addition, mechanical deformation will induce the formation of cracks and voids at the CD-SiO2 NPs and PDMS matrix, which can amplify light scattering and enhance the ability of CD-SiO2 NPs to absorb scattered light. These synergistic interfacial phenomena collectively govern the optomechanical switching behavior of the SMOF system, consequently achieving its broadband transmittance regulation while simultaneously amplifying the photoluminescence intensity. These distinctive optomechanical characteristics establish SMOF as a multifunctional platform, particularly suitable for stimuli-responsive privacy protection, UV-shielding applications, and persistent-luminescence-based traffic safety systems.

Thermoplastic composite tubes are widely used in aerospace and transportation for their high strength-to-weight ratio, excellent energy absorption, design flexibility and high-temperature stability, serving as key crash-energy absorbers in automotive and aerospace structures. However, fabricating low-density tubes with high energy absorption and clarifying their failure mechanisms remain challenging. Herein, a novel wrapping-braiding-hot pressing process is reported for continuous carbon-fiber reinforced polyetheretherketone (CCF/PEEK) tubes with ultra-low density (0.5-0.6 g/cm3) and high specific energy absorption (SEA, 55.8 kJ/kg). PEEK powder impregnation and filament wrapping enhance fiber-resin wetting. Under quasi-static compression conditions, axial yarn reinforcement boosts performance: tubes with 14 axial yarns exhibit 77.5% higher total energy absorption (EA) and 53.3% higher SEA than those without axial yarns. At 170 degrees C, the compressive performance and SEA retention exceed 95%. X-ray computed tomography reveals failure modes including braid rupture, prepreg fracture, matrix cracking and delamination, providing a novel strategy for high-performance thermoplastic composite tube fabrication.

Dynamic optical materials show significant potential for advanced information encryption and anticounterfeiting, yet multimodal non-contact decryption systems remain challenging. Herein, a feasible strategy is proposed for spatiotemporal encryption through non-contact modulation of structural color (SC), photochromic color (PC), and fluorescent color (FC). This secure film is achieved via compartmentalized microdroplet encapsulation and curing (CMEC) technique based on crosslinked polydimethylsiloxane. The microdroplet integrates three components: (i) superparamagnetic Fe3O4@SiO2 nanoparticles (SPIONs) for magnetically responsive SC modulation, (ii) methyl-functionalized spiropyran (MSP) for reversible PC switching and (iii) nitrogen-doped carbon dots (NCDs) that enable time-evolving FC transitions via fluorescence resonance energy transfer with MSP. Initial static information concealment is achieved via optimization of SPIONs parameters. Spatial encryption synergizes SC (red to purple) with PC (red), while temporal security stems from adjustable FC (from blue through pink to red). The CMEC strategy allows facile preparation of multimodal films with versatile compositions. We arrange pixel arrays in single, dual, and triple modes. This yields a Morse-code-based spatiotemporal encryption system that affords over 7.9 x 1028 rewritable programming possibilities. This methodology establishes a generalizable platform for multimodal high-security encryption systems toward practical applications.

In nature, plenty of creatures show iridescent colors or special wettability deriving from their surface or interface structure for communication, courtship, defence, etc. To mimic these structures, colloid packings driven by physical forces constitute one of the cheapest, simplest, and quickest techniques. In this chapter, the development of structural color and dynamic modulation from the packings of ordered or quasi-amorphous structures is presented. Moreover, the superhydrophobic surfaces from numerous colloids (spherical, stringed, flower-like, etc.) are also demonstrated.

Functional textiles are becoming importance across various fields like outdoors, healthcare, protection, sports and military. However, it remains challenging to achieve durable multifunctional textiles generally due to weak interface between functional coatings and fibers. Herein, an effective strategery for durable multifunctional textiles with self-cleaning and thermal management (SCTM) is reported. Uniform films containing tungstendoped vanadium dioxide (W-VO2) nanoparticles and poly(dimethylsiloxane) (PDMS) with surface wrinkling structure were coated on PET fabric facilely through dipping and Ar plasma treatment. The SCTM fabric demonstrates a contact angle of 162 degrees, a sliding angle of 5.1 degrees and withstand rubbing for over 500 cycles under 10.5 kPa. Furthermore, the thermochromic property of W-VO2, in conjunction with enhanced scattering by surface wrinkles, enables the SCTM fabric to achieve maximum temperature reduction of 5.5 degrees C under direct sunlight and electricity savings rate of 26.8 % in summer. This study presents a new approach to designing durable multifunctional materials.

A flexible thermal protective system is highly desirable for maintaining the safety of the human body or spacecraft with complex profiles. However, it is still challenging to attain high deformability and rapid cooling, especially with intense chemical fire or aerodynamic heat. Inspired by the sweat gland of human skin, herein an adaptive two-layered skin is developed based on inner hollow porous TPU/PVC fibers embedded in silicone for water transportation and outer PET spacer fabric for water storage and transpiration. The TPU/PVC hollow fibers were optimized with good superhydrophilicity, high porosity of 79%, and excellent deformability (∼303%). The adaptive thermal protective skin (∼5 mm) shows good biaxial deformability (∼150%) and attains a comfortable temperature (∼46 °C) under high heat flux (420 kW/m2) within 1 s. Finite element simulation reveals that the spacer fabric with an optimized thickness of 9 mm can reduce the 1000 °C surface temperature to 20 °C in 0.7 s. We believe that this adaptive thermal protective skin paves an effective way to achieve rapid cooling for the human body, robotics, and spacecraft under extreme heat environments.

Information encryption and anti-counterfeiting have attracted much interest, in which the most crucial part is the stimulus-responsive materials. However, most reports on the materials focus on visual-type encryption dominated by optical properties, including color, transparency, fluorescence, or phosphorescence. Inspired by numerous creatures in nature which utilize morphology and color change to communicate, here, a visual-morphological integrated encryption actuator is reported based on noncontact light stimulation. A facile bilayer structure is proposed, consisting of a bottom layer of multi-walled carbon nanotube-doped liquid crystal elastomer (MWCNT-LCE) and a top layer of cholesteric LCE (CLCE). Upon near-infrared (NIR) irradiation (<10 s), reversible shape changes can be achieved due to phase transitions of the MWCNT-LCE layer. Full-spectrum color shift (Delta lambda = 240 nm) is exhibited due to contraction of the CLCE helix to adjust the pitch. Programmable deformation combined with reversible color modulation endows encode and encrypt more than 43 million pieces of information. Furthermore, adaptive camouflage based on morphological and color changes is also shown, improving the survivability of soft robots in complex environments, such as concealment and task execution efficiency. This work provides a novel paradigm for designing next-generation integrated information encryption, anti-counterfeiting systems, intelligent sensing, and adaptive camouflage technologies.

Integrated actuator-sensor systems with real-time optomechanical feedback are critical for intelligent aerospace platforms and advanced security technologies. However, existing adaptive materials often lack synergistic control of dynamic actuation and optical sensing in a single device. Inspired by the chromatophore-muscle synergy in cephalopods, a bilayer actuator-sensor composite combining a carbon nanotube-reinforced shape memory polymer (CNT/SMP) actuator and a strain-sensitive cholesteric liquid crystal elastomer (CLCE) optical sensor is presented herein. The CNT/SMP actuator is engineered to exhibit 98.5 % shape fixity with rapid photothermal recovery (<60 s), achieving near-infrared (NIR)-triggered programmable deformations through its exceptional broadband absorption and photothermal conversion. Simultaneously, the CLCE layer functions as a mechanochromic sensor, achieving wide-range visible-spectrum optical feedback (470-650 nm) via strain-modulated helical nanostructures. Pioneering bilayer integration of CNT/SMP (photothermal actuation) and CLCE (mechanochromic sensing) overcomes single-function limits, with tunable CNT content (ensuring high shape fixity and rapid photothermal responsiveness) and chiral dopant concentration (enabling visible-spectrum (470-650 nm) color feedback). The actuator-sensor system demonstrates versatile applicability in biomimetic soft robotics, adaptive morphing aircraft platforms, and multilevel security field. This work achieves enhanced real-time optomechanical feedback and environmental adaptability through dynamic actuation-sensing synergy, significantly advancing the implementation of stimuli-responsive smart systems in defense technologies and secure identification scenarios.

Inspired by the ubiquitous surface wrinkling in nature, artificial wrinkling from the instability of soft matter has attracted increasing interest due to their tunable adhesion, electricity or optical performance, etc. However, the extraordinary property and practical applications of wrinkling on spherical substrate have been seldom reported. Here we showed enhanced laser attenuation properties from surface wrinkled carbon nanotube (CNT)-doped PDMS microspheres. Tuned by the chemical oxidation time, the surface pattern undergoes an evolution: formation of wrinkling, increase of wavelength, dimples to elliptical dent-like patterns. It is proved that the greatest scattering of laser (808 nm) lights is achieved from the wrinkles with appropriate wavelength. Moreover, moderate incorporation of CNT (0.125 wt%) not only enhances the absorption of laser light but also effectively avoids ablation. Coupling with the work medium (water) of high phase transition enthalpy, a laser attenuation up to 75 % can be achieved from wrinkled microspheres-based solution (15 wt%). Through the atomization device, the mist including wrinkled microspheres demonstrates stable laser attenuation performance (similar to 72 %) with the advantages of angle-free, non-contact and large-area. This novel laser attenuation system containing wrinkled microspheres paves a new way in engineering applications of surface wrinkling on spherical substrates.

Superhydrophobic (SH) surfaces have served as a key strategy to decrease flow resistance via gas-liquid interfaces in numerous fields such as pipeline transportation, microfluidics, the shipping industry, and so forth. However, an underwater SH surface with both good drag reduction and plastron restoration from a fully wetted state remains challenging. Inspired by the hairy structure of water spiders, herein, an underwater respirable skin (URS) with a microcone-nanoparticle structure is demonstrated. URS with different geometric parameters is achieved through laser microfabrication and chemical vapor deposition. The plastron can be completely restored from the fully wetted state after 11.6 s of air jetting, and a drag reduction rate of 15.7% ± 0.2% can be achieved. The theoretical and numerical results reveal a contradictory effect between drag reduction and plastron restoration. Our study suggests promising comprehensive perspectives for marine vehicle coatings and methodologies for sustainable drag reduction surfaces, considering both plastron restoration and the drag reduction rate.

Constructing a dual-mode information encryption material with dynamic cracking-wrinkling structures and tunable luminescence properties is a promising way to enhance information security. However, it is hard to achieve multilevel information encryption due to the limited responsiveness and encryption capacity of current dual-mode information encryption materials. Here, we demonstrated a dual-responsive optical membrane that integrates highly encrypted ultralong-lifetime room-temperature phosphorescent (ULRTP) materials and mechanical response cracking-wrinkling structures toward multistage information encryption. First, the new ULRTP materials with ultralong-lifetime (2.66 s) and high phosphorescence quantum yield (PHQY, 35.3%) were synthesized by using boric acid, citric acid, and sodium bromide. In this system, the external heavy-atom effect (EHE) is induced by Br- anions, which can promote the intersystem crossing rate (ISC) and increase the PHQY. While the nonradiative decay rate of the triple excitons are effectively reduced by the electrostatic interaction between Na+ cations and Br- anions, which can significantly prolong the phosphorescence lifetime. Furthermore, the cracking-wrinkling patterns are induced by an ultraviolet/ozone-treated optical film. Under selective stimulation, this optical membrane can dynamically adjust its surface structure and phosphorescent color. This smart film with dynamic cracking-wrinkling and phosphorescence shows potential applications in anti-counterfeiting and message encryption.

Benefitting from lightweight, high strength, long life, and green recyclability, continuous fiber reinforced thermoplastic composite (CFTPC) pipes have attracted extensive interest, especially in the on-orbit additive manufacturing of structural components. However, the preparation of CFTPC pipes remains challenging due to the on-orbit limited space and high processing temperature of thermoplastic resin. Here, we report an effective approach for high performance carbon fiber/polyether-ether-ketone (CF/PEEK) thin-walled pipes via bidirectional reinforcement using the pultrusion-winding technique. The continuous fabrication of thin-walled pipes can be achieved, but the limitation by the size of core mold is also broken. The compressive and shear performance of CF/PEEK pipes with different layer designs have been studied based on experiments and simulations. With the increase in axial prepreg tape layer, the resultant CF/PEEK pipes exhibit greatly improved axial compression strength. The finite element analysis indicates that the maximum axial stress is decreased due to the axial enhancement. The flexural strength is greatly proved with pultrusion–winding cycles. The simulation confirms that the circumferential strain is effectively reduced. The high performance of bidirectional reinforced CF/PEEK pipes and the facile controllability of this approach highlight their suitability for utilization in on-orbit manufacturing of large-scale structures.

The prevention of drying-induced cracking is crucial in maintaining the mechanical integrity and functionality of colloidal deposits and coatings. Despite exploring various approaches, controlling drying-induced cracking remains a subject of great scientific interest and practical importance. By introducing chain-like particles composed of the same material and with comparable size into commonly used colloidal suspensions of spherical silica nanoparticles, we can significantly reduce the cracks formed in dried particle deposits and achieve a fivefold increase in the critical cracking thickness of colloidal silica coatings. The mechanism underlying the crack suppression is attributed to the increased porosity and pore sizes in dried particle deposits containing chain-like particle, which essentially leads to reduction in internal stresses developed during the drying process. Meanwhile, the nanoindentation measurements reveal that colloidal deposits with chain-like particles exhibit a smaller reduction in hardness compared to those reported using other cracking suppression approaches. This work demonstrates a promising technique for preparing colloidal coatings with enhanced crack resistance while maintaining desirable mechanical properties.

Cephalopod skin is capable of fast color changing enabled by tunable skin transparency as well as structure color. Under this inspiration, herein, a flexible surface with unique hierarchical structure that integrates both transparency change in chemical color (optical scattering) and structure coloration (optical interfering) is developed by harnessing wrinkling instability, thanks to the interfacial Au catalysis in soft lithography. As a result, a hierarchical structure in terms of wrinkled film overlaid by nano‐dome array is obtained in the flexile surface. Experiments find that subject to biaxial strains from 0% to 60%, the hierarchical surface first experiences a transition from nontransparent to transparent owing to the flattening of the wrinkles and then exhibits iridescence structure color shifting from blue to red. The switchable and dynamical tunable mechanochromic characteristics are demonstrated in a smart window, offering potentials for developing flexible devices with optical multiple functionality.

Developing scalable and durable superhydrophobic (SH) coatings in harsh rainy/icy/abrading environments is attractive for various applications, yet has proven challenging. Here we report an ultra-robust SH coating via physical bonding and chemical crosslinking of polystyrene microspheres (PS MPs). The facile preparation includes co-spray of PS MPs and perfluorinated nanoparticles, hot-press and thermal evaporation. The 3D interconnected polymeric network is enhanced due to the semidissolving-based bonding and Friedel-Crafts reaction-based chemical crosslinking of PS MPs. Compared with the pristine SH coatings, the durability of our SH coating is increased by 2230%, 340% and 1440% through bidirectional abrasion, water impact and freeze-thaw tests, respectively. Both the facile fabrication and the great durability highlight their applications in anti-icing, anti-corrosion, self-cleaning, etc. Our strategy provides a generic design for multifunctional engineering durable coatings based on polymeric network.

Capturing thermal radiation using highly infrared (IR)-transparent materials have drawn great attention for diverse applications, such as IR guidance, IR detection, thermal radiation imaging, radiative cooling etc. However, the previously reported IR-transparent materials have the bottleneck of lacking superhydrophobicity, resulting in the degradation due to the dust, fog, rain, frost outdoors. Here, a durable IR-transparent superhydrophobic coating is reported via the spraying of polyester (PE) microspheres and fluorinated ZnS nanoparticles (NPs). Due to the high transmittance of ZnS and PE, the coating shows excellent IR transparency (around 90 %) in 8 --- 14 mu m thermal IR band. Benefitting from the robustness of 3D connected PE network, the coating maintains superhydrophobicity after 180 cycles of linear wearing under 6 kPa. Moreover, the water jetting/atomizing/dust tests indicate that this coating effectively ensures the high accuracy of IR imaging lens under rainy/foggy/dusty environments. This coating on fabrics also achieves a remarkable radiative cooling effect for outdoor conditions to keep human body comfortable. With its facile preparation and versatile features, this coating has great potential on IR window, IR imaging and personal thermal management.

Continuous fiber reinforced thermoplastic composites (CFTPCs) have shown advantages such as high strength, long life, corrosion resistance, and green recyclability. Three-dimensional printing of CFTPCs opened up a new strategy for the fabrication of composites with complicated structures, low cost, and short production cycles. However, a traditional 3D printing process usually causes poor impregnation of the fiber or surface damage of the fiber due to the short impregnation time or high viscosity of the thermoplastic resin. Here, continuous carbon fiber/poly(ether-ether-ketones) (CCF/PEEK) wrapped yarn was fabricated via powder impregnation and using double spinning technology for the 3D printing. The concentration of PEEK powder suspension and wire speed were optimized as 15% and 2.0 m/min. The twist of wrapped yarn was optimized as 1037 T/m. Mechanical testing showed that the 3D-printed composite wire had excellent tensile and bending strength, which was about 1.6~4.2 times larger than those without the powder pre-impregnation process. It is mainly attributed to the improved impregnation of the CF which took place during the powder pre-impregnation process. We believe that our research on wrapped yarn for 3D-printed composites provides an effective strategy for the 3D printing of composites with enhanced mechanical properties.

We demonstrate an effective strategy for the dual control of color and transparency based on limited assembly of a photonic liquid induced by patterned electrodes. This device can achieve a color change from orange-red to blue and a transparency change from opaque to translucency.

Knitted seamless sportswear offers 'body-mapped' comfort and support, but there is a risk of exposing the human body in public due to the low density and large fabric deformation of the sportswear when wearing it. This paper presents an experimental study on the light transmission behavior of different weft-knitted fabrics for seamless sportswear in different stretching modes to understand the light transmission principle. Three plain knit fabrics for seamless sportswear made from three yarn combinations were compared: a polyamide 6 (PA6) yarn, a combination of spandex and PA6 yarns, and a combination of spandex, PA6, and polyethylene terephthalate (PET) yarns. Three modes of stretching were performed on the three fabrics, namely uniaxially, uniaxially with transverse restraint, and biaxially, to simulate wear deformation. The stretched fabrics are analyzed in terms of cover factor, thickness, and light transmission. The results showed that light transmission increases with increasing tensile strain. The presence of restraint further increases the light transmission, and biaxially stretched fabrics have the greatest light transmission. The thinnest PA6 fabric has the lowest cover factor and the highest light transmission, while plating a spandex/PA6 covered yarn on a PA6 yarn shrinks and tightens the fabric, and therefore reduces the light transmission. Adding an additional PET yarn reduces shrinkage and thickness, increasing light transmission. Light passing through the fibers and loop meshes of a fabric accounts for total light transmission. Plating a coarser elastomeric yarn into weft-knitted fabrics for seamless sportswear is an effective way to increase the spaces in yarns and shrink the loop meshes, thereby reducing the light transmission.