Disordered superstructure sub-environmental radiation cooling fiber and preparation method and application thereof

Abstract

The present application belongs to the technical field of radiative cooling fibers, and relates to a disordered superstructure sub-environment radiative cooling fiber as well as a preparation method and application thereof. The fiber is an organic-inorganic hybrid photonic glass superstructure material with disordered super-uniform characteristics, which is composed of a dielectric polymer as a continuous phase, a discrete phase inorganic nanoresonator embedded in situ and covered by the continuous phase, and a porous scattering network fixed by non-solvent phase separation and freeze-drying. The band gap energy Eg of the inorganic nanoresonator is greater than 3.0 eV. In the preparation, the dielectric polymer and the inorganic nanoresonator are first added to a solvent, and then an isotropic spinning dope is formed through the combined action of surface charge regulation and steric hindrance. The fiber is obtained by wet spinning, non-solvent phase separation and freeze-drying in sequence. The low absorption of sunlight, high backscattering and high mid-infrared emission of the fiber can be synergistically realized at the single fiber scale. The method is simple. When applied, the fiber has air permeability and lightness.

Description

Technical Field

[0001] This invention belongs to the field of radiation cooling fiber technology, and relates to a disordered metamorphic sub-environment radiation cooling fiber, its preparation method and application. Background Technology

[0002] Extreme heat stress events caused by global warming are pushing the physical limits of the human body's biological thermoregulation mechanisms. Traditional environmental heat management strategies, constrained by the energy efficiency bottleneck of the Carnot cycle and enormous energy consumption, are no longer sufficient to meet the needs of sustainable development. Therefore, constructing a personal microclimate management system that can operate independently of external energy input has become a key issue in the fields of thermophysics and materials science.

[0003] Passive radiative cooling, as a negative entropy flow generation technology utilizing the cosmic background (~3 K) as the ultimate cold source, offers a theoretical possibility for overcoming the aforementioned challenges. Its core physical mechanism lies in establishing a non-reciprocal photon transport channel through atmospheric transparency windows (8~13 μm) by using spectrally selective surfaces to block the injection of short-wave solar radiation (0.3~2.5 μm) heat while simultaneously blocking it. However, translating this photonic principle into flexible, wearable fabric still faces a severe trilemma of topology-thermodynamic properties-mechanical flexibility. Although radiative cooling for human thermal management has become a popular research direction, existing techniques still have certain limitations.

[0004] While existing technological attempts have made progress in certain dimensions, significant theoretical defects and engineering difficulties remain: (1) Limitations of single-mode photon transport: Reference 1 (Nanoporous polyethylene microfibres for large-scale radiative cooling fabric. Nat Sustainability 1, 105–112 (2018)) utilizes Mie scattering of nanoporous polyethylene (Nano-PE) to achieve visible light blocking. However, its single chemical component based on semi-crystalline polyolefin lacks infrared active phonon modes, and its film morphology leads to mutual repulsion between mechanical modulus and moisture permeability, making it difficult to meet complex human mechanical requirements. (2) Macroscopic challenges of low-dimensional materials: The radiation cooling film based on silica nanofibers proposed in Reference 2 (RadiativeCooling Electrostatic Spinning Fabric with Environmental Adaptability and Robustness. ACS Applied Materials & Interfaces, 2025 17 (37), 52498-52509.) enhances emissivity by utilizing the Fröhlich resonance of Si-O bonds. However, the inherent low flux of the electrospinning process and the weak interfacial bonding of the micro- and nanofiber membranes make it difficult to achieve processing from laboratory to industrial levels, and it cannot withstand the mechanical requirements generated by human movement. (3) Parasitic dependence of heterogeneous interfaces: The metamaterial fabric developed in Reference 3 (Hierarchical-morphology metafabric for scalable passive daytime radiative cooling. Science, 373, 692–696 (2021.) introduces the concept of structure, but the realization of its sub-environmental cooling function depends on covering it with a layer of commercially available fluoropolymer (PTFE) film. This heterogeneous laminate structure not only introduces additional interfacial thermal resistance, disrupting the integrity of the photonic bandgap, but also makes it impossible to achieve self-consistent net cooling power output within a single fiber.

[0005] Existing radiation cooling fibers with heterogeneous structures and irregular cross-sections typically focus on polyurethane matrices, the lateral dimensions of inorganic micro / nanosheets, irregular cross-sections, and wicking humidity regulation as their core design elements. Their emphasis is on improving radiation cooling and humidity regulation performance through sheet-like fillers and irregular cross-sections. Therefore, simple polymer / inorganic sheet-like filler wet spinning cannot provide a structural design basis for steady-state sub-environmental cooling at the monofilament scale.

[0006] In summary, the current field urgently needs a material system that can simultaneously achieve high-broadband light reflection and strong coupling of phonon polaritons at a single fiber scale through bottom-up structural assembly.

[0007] Therefore, it is of great significance to study a disordered metamorphic sub-environmental radiation cooling fiber, its preparation method and application, in order to solve the problems existing in the prior art. Summary of the Invention

[0008] The purpose of this invention is to solve the problems existing in the prior art and to provide a disordered metamorphic sub-environment radiation cooling fiber, its preparation method and application.

[0009] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0010] A disordered metamorphic sub-environmental radiation cooling fiber is an organic-inorganic hybrid photonic glass metamaterial with disordered and ultra-uniform characteristics. It is a typical multiphase condensed matter system, consisting of a dielectric polymer as a continuous phase (matrix), discrete-phase inorganic nanoresonators (resonant units) embedded in situ and confined by the continuous phase, and a porous scattering network fixed by non-solvent-induced phase separation and freeze-drying. This multiphase condensed matter system achieves steady-state sub-environmental radiation cooling by using non-reciprocal spectral modulation, synergistically utilizing interband transition blocking of electrons, Anderson localization-induced broadband backscattering, and phonon-polariton enhanced thermal emission. The fiber acts as a random scattering medium, selectively decoupling solar radiation gain from thermal radiation through spectral modulation, establishing a negative thermodynamic potential energy channel to deep space heat sinks.

[0011] The inorganic nanoresonator is a three-dimensional micro / nano particle with a random isotropic embedded distribution within the radial cross section of the fiber, forming a multi-scale refractive index mismatch scattering center between air, dielectric polymer and inorganic nanoresonator.

[0012] The bandgap energy of the inorganic nanoresonator is Eg>3.0 eV; the dynamic light scattering equivalent hydrodynamic diameter of the inorganic nanoresonator is 100 nm~2.5 μm.

[0013] In the field of micro-nano photonics, "inorganic nanoresonator" is a recognized term referring to three-dimensional micro- and nanoparticles capable of enhancing electromagnetic field interactions through Mie scattering, intrinsic lattice vibrations, or localized surface phonon polaritons. In this invention, the inorganic nanoresonator simultaneously satisfies two types of parameter constraints: first, a bandgap energy Eg > 3.0 eV, used to reduce its intrinsic absorption in the visible-near-infrared main solar spectrum region, thus reducing photothermal conversion caused by the inorganic phase; second, an equivalent hydrodynamic diameter of 100 nm to 2.5 μm, measured by dynamic light scattering, in a polar aprotic solvent similar to the spinning solution at 25 ± 1 °C, used to limit the solvation particle size and aggregation scale of the inorganic nanoresonator in the actual spinning solution. These parameters are not simply descriptions of material size, but rather serve to simultaneously determine the design boundaries of "low absorption" and "effective scattering center size" before fiber formation.

[0014] This invention relates to a disordered meta-environmental radiation-cooled fiber that achieves energy transport management through non-reciprocal spectral engineering: In the solar radiation band of 0.3–2.5 μm, inorganic nanoresonators with a bandgap energy Eg > 3.0 eV reduce intrinsic light absorption; an equivalent hydrodynamic diameter of 100 nm–2.5 μm maintains a solvated scattering center in the spinning solution that matches the wavelength of sunlight; after the inorganic nanoresonators are in-situ embedded and confined by the dielectric polymer continuous phase, they, together with the nanoscale to microscale pores generated by non-solvent-induced phase separation, form a three-dimensional multi-scale refractive index mismatch scattering center, reducing the mean free path of photon transport and enhancing broadband backscattering. In the atmospheric transparency window band of 8–13 μm, the infrared active vibrations of the dielectric polymer backbone and the lattice phonon modes of the inorganic nanoresonators synergistically increase the infrared emissivity, thereby driving heat flow from the fiber to deep space heat sinks for dissipation, achieving steady-state sub-environmental radiation cooling at the single-filament scale.

[0015] As a preferred technical solution:

[0016] As described above, the disordered metamorphic sub-environmental radiation cooling fiber has a dielectric polymer whose molecular chain segments contain functional groups capable of generating strong dipole moment changes in the 7-14 μm wavelength range to approximate the blackbody radiation limit. Simultaneously, the dielectric polymer must possess viscoelastic rheological characteristics and fiber formation kinetics window suitable for wet spinning processes. The dielectric polymer is selected from block copolymer thermoplastic polyurethane (TPU), polyacrylonitrile (PAN), polyvinyl chloride (PVC), poly(p-phenylene terephthalamide) (PPTA), and their derivatives.

[0017] The dielectric polymer matrix not only serves as mechanical support, but its functional groups (such as COC bonds) on the molecular chains also provide intrinsic infrared activity. This structure fulfills various functions:

[0018] Visible light blocking function: The inorganic nanoresonator with high refractive index contrast forms strong dielectric fluctuations with the pores. When this random distribution satisfies a specific spatial correlation, it induces the Anderson localization effect of photons, minimizing the mean free path of photons in the 0.3~2.5 μm band, thereby achieving extremely high broadband solar reflectivity without relying on expensive reflective layers.

[0019] Infrared thermal emission function: Inorganic particles modulated by interface band engineering have abundant localized surface phonon polariton modes. These modes are strongly coupled with the molecular vibrational modes of dielectric polymers in the 8~13 μm band, which greatly enhances the photon density of states, thereby achieving a very high infrared emissivity.

[0020] Thermodynamic equilibrium function: Because the above two mechanisms achieve spectral decoupling within a single fiber, the system can establish a negative thermodynamic potential energy channel from room temperature environment to outer space (~3 K), thereby breaking through the physical threshold of steady-state sub-environmental cooling at the single filament scale.

[0021] The disordered metamorphic sub-environmental radiation cooling fiber described above, wherein the inorganic nanoresonator is selected from one or more of the following: corundum phase alumina (Al2O3), wurtzite zinc oxide (ZnO), monoclinic zirconium oxide (ZrO2), tantalum pentoxide (Ta2O5), barite type barium sulfate (BaSO4), amorphous or crystalline silicon dioxide (SiO2), and silicon nitride (Si3N4).

[0022] As described above, in a disordered metamorphic sub-environmental radiation-cooled fiber, the inorganic nanoresonator accounts for 5-50% of the mass percentage of the dielectric polymer. The inorganic nanoresonator is not simply a physical filler, but rather, through the combined effect of surface charge regulation and the steric hindrance generated by the polymer adsorption layer or molecular brush, the inorganic nanoresonator is interfacially coupled with the dielectric polymer continuous phase. During wet spinning and phase separation, it is embedded in situ in the pore walls or network nodes, thereby maintaining rheological spinnability while transforming the solvated particle size in the dope stage into the effective scattering center size inside the fiber, achieving a balance between optical scattering cross-section and mechanical flexibility.

[0023] The disordered metamorphic sub-environmental radiation cooling fiber described above has a linear mass density of 0.5~55 D and a diameter of 0.01~2 mm; this size range is designed to optimize the specific surface area to enhance convective heat transfer while maintaining sufficient optical thickness to prevent sunlight penetration.

[0024] This invention also provides a method for preparing disordered metamorphic sub-environmental radiation cooling fiber as described in any of the preceding claims. First, a dielectric polymer and an inorganic nanoresonator are added to a polar aprotic solvent. Through surface charge regulation and the combined effect of steric hindrance generated by the polymer adsorption layer or molecular brush, the inorganic nanoresonator achieves a zeta potential absolute value of no less than 25 mV at 25±1 °C, and an equivalent hydrodynamic diameter growth rate of no more than 20% after 24 h, forming an isotropic spinning solution. Then, the spinning solution is placed in a shear flow field and extruded using a wet spinning process, followed by non-solvent-induced phase separation to obtain nascent fibers. Finally, the nascent fibers are freeze-dried. Freeze-drying removes the solvent while suppressing pore collapse caused by capillary forces, thus fixing the pore network formed by phase separation and the distribution of embedded inorganic nanoresonators, resulting in disordered metamorphic sub-environmental radiation cooling fiber.

[0025] Among these methods, surface charge modulation is used to establish a repulsive potential barrier of like charges on the surface of inorganic nanoresonators, preventing the formation of large-sized irreversible aggregates in polar aprotic solvents. This is achieved by: adjusting the apparent pH of the spinning solution to deviate from the isoelectric point of the inorganic nanoresonator; introducing a background electrolyte of specific ionic strength; and performing charged ligand exchange treatment on the surface of the inorganic particles.

[0026] The effect of surface charge modulation is not simply to improve dispersibility, but to limit the equivalent hydrodynamic diameter of the inorganic nanoresonator before fiber formation, thus maintaining its quasi-steady-state distribution during shear flow and solvent exchange in the coagulation bath. A double-layer structure consisting of a compact layer and a diffuse layer forms on the surface of the inorganic nanoresonator. This electrostatic barrier generates long-range repulsive forces, counteracting van der Waals forces between particles and preventing secondary aggregation of particles in static fluid conditions, low-shear states, or at the coagulation bath inlet.

[0027] Steric hindrance modulation is used to construct polymer adsorption layers or molecular brushes on the surface of inorganic nanoresonators, causing chain segment compression and a decrease in conformational entropy when particles approach each other, thereby forming an entropy repulsion barrier. This can be achieved by adding dispersants with specific molecular weights, such as polyacrylic acid (PAA), polyethylene glycol (PEG), or polyvinylpyrrolidone (PVP), to the spinning solution; or by grafting polymer brushes, such as polyacrylate molecular brushes, onto the particle surface. Preferably, the inorganic nanoresonator, after surface charge modulation and steric hindrance modulation, exhibits an equivalent hydrodynamic diameter growth rate of no more than 20% after being placed at 25±1 °C in an aprotic solvent of the same polarity as the spinning solution for 24 h.

[0028] The further role of steric hindrance modulation lies in promoting the confinement of inorganic nanoresonators by the dielectric polymer continuous phase after fiber formation. The grafted or adsorbed polymer segments entangle or interact with the dielectric polymer segments, allowing the inorganic nanoresonators to be preferentially fixed in the pore walls, network nodes, or polymer-rich phase during non-solvent-induced phase separation, avoiding the formation of sheet-like stacked structures parallel to the fiber axis, thereby obtaining a three-dimensional isotropic photon scattering network.

[0029] Existing technologies typically use pH adjustment, coupling agent treatment, dispersant addition, or drying as conventional process steps. This invention, however, couples these steps with two optical design parameters: band gap energy and equivalent hydrodynamic diameter. First, inorganic nanoresonators with low absorption and suitable solvation particle size are screened and stabilized in the stock solution stage. Then, this scale information is fixed into a porous scattering network within the fiber through hindered phase separation and freeze-drying. The key innovation of this invention lies in transforming the "dispersion-phase separation-drying" process from a conventional fiber-forming process into a precise photonic structure construction process, solving the problems of uncontrollable scattering centers, inorganic phase aggregation, and spectral impedance mismatch inherent in existing technologies during sub-environmental cooling at the single-filament scale.

[0030] The formation mechanism of the special structural fibers of this invention:

[0031] First, the surface barrier modulation utilizes the extended DLVO theory, introducing long-range electrostatic repulsion (electric double layer) and entropy repulsion (polymer brush) on the nanoparticle surface to create an extremely high first minimum barrier on the potential energy curve. This means that in the high-shear flow field of subsequent wet spinning, even if the fluid undergoes drastic deformation, the particles can still maintain a thermodynamically quasi-steady-state distribution, providing a precursor basis for the formation of "ultra-uniform" topology.

[0032] Secondly, non-equilibrium phase transition kinetics serve as a "template" for structure generation. When the spinning solution is injected into the coagulation bath, the drastic change in the chemical potential gradient induces phase separation in the system. Unlike traditional nucleation-growth mechanisms, spinoline decomposition does not require overcoming the nucleation energy barrier; instead, it involves the spontaneous amplification of compositional fluctuations throughout the entire space. Structures generated by this mechanism possess a natural bicontinuity and consistency in characteristic scales. By controlling the "hindered" timing (i.e., increasing viscosity through solvent exchange until gelation), this unstable dynamic process can be locked at a predetermined optical resonance scale.

[0033] Finally, freeze-drying ensures the "in-situ freezing" of the porous scattering network and the embedded inorganic nanoresonator distribution by suppressing the surface tension at the liquid-gas interface. These pores, generated by phase separation, act as low-refractive-index centers, forming refractive-index mismatch scattering centers with the high-refractive-index inorganic nanoresonators and the dielectric polymer matrix, reducing the diffusion coefficient of photons in the medium and causing multiple scattering. Unlike simply drying fibers, freeze-drying in this invention is used to preserve the photonic glass topology designed with bandgap energy and equivalent hydrodynamic diameter.

[0034] As a preferred technical solution:

[0035] In the method for preparing a disordered metamorphic sub-environment radiation-cooled fiber as described above, the shear flow field is formed by controlling the shear stress through an extrusion speed of 700–1200 m / min. The formation of the shear flow field induces axial orientation crystallization of polymer chains, which is crucial for the fiber's strength and optical anisotropy. This is because the extrusion speed determines the initial tensile state of the chain segments, while the strain rate further maintains and locks in this orientation. The high axial orientation not only endows the fiber with extremely high tensile strength, but more importantly, it creates "optical anisotropy," elongating the photon propagation path in the fiber's cross-section and significantly improving the lateral backscattering efficiency. The axial tensile strain rate is controlled by the winding speed, set to 10 m / min–5000 m / min; by adjusting the draw ratio between spinning and winding, the free volume of the amorphous region and the phonon mean free path of the crystalline region within the fiber are precisely controlled.

[0036] The method for preparing disordered metamorphic sub-environment radiation-cooled fibers as described above, wherein non-solvent-induced phase separation molding refers to the process where the spinning solution is extruded through a spinneret and then enters a coagulation bath, which is a mixture of deionized water and ethanol, and nascent fibers are obtained through solvent / non-solvent exchange.

[0037] Both deionized water and ethanol can induce phase separation in the coagulation bath, but the resulting microstructures are drastically different. Pure deionized water has a high diffusion coefficient and extremely rapid solvent exchange, easily producing large finger-like pores, which can impair mechanical strength. Pure ethanol, as a weak non-solvent, has a slow diffusion rate, inducing delayed phase separation and easily producing uniform honeycomb-like micropores or sponge structures. However, by using a binary mixture and adjusting the activity ratio of water / ethanol, phase separation can be locked at a specific stage of "spinolatilization," thereby obtaining the pores with specific spatial correlation required by this invention.

[0038] The method for preparing disordered metamorphic sub-environmental radiation cooling fiber as described above involves, in order to increase the photon escape cone angle and optimize the specific surface area, designing the fiber cross-section as a non-rotationally symmetric topology, and the cross-sectional shape of the spinneret orifice on the spinneret assembly is one or more of the following: Y-shaped, pentagonal, trilobal, quadrilobal, pentlobal, fan-shaped, and hollow structure.

[0039] The method for preparing disordered metamorphic sub-environmental radiation-cooled fibers, as described above, uses a total solid mass fraction of 5-100% for the dielectric polymer and inorganic nanoresonators in the spinning solution to construct a continuously spun photon scattering network and ensure that the diffusion length of photons within the medium is less than the fiber diameter. This concentration window covers the kinetic range from dilute solutions to crowded dispersion systems. By adjusting the solid content, the distribution of inorganic nanoresonators in the spinneret assembly and the characteristic scale of hindered phase separation in the coagulation bath can be controlled.

[0040] The present invention also provides an application of a disordered metamorphic sub-environmental radiation cooling fiber as described in any of the preceding claims, wherein the disordered metamorphic sub-environmental radiation cooling fiber is used to construct a two-dimensional photonic fabric with a rough surface through orthogonal weaving or warp-weft interlocking processes.

[0041] Invention principle:

[0042] The present invention provides a disordered metamorphic sub-environmental radiation cooling fiber, which is composed of a dielectric polymer as a continuous phase and a wide-bandgap inorganic nanoresonator embedded therein as a discrete phase. From a physical architecture perspective, the fiber is not simply filled with particles, but rather constructs a bicontinuous, porous topological network formed by the decomposition of hindered spindle lines. This overcomes the problems of spectral impedance mismatch, severe structural dispersion, and difficulty in achieving mechanical compliance faced by existing technologies in achieving steady-state sub-environmental cooling.

[0043] Firstly, this invention addresses the problems of spectral impedance mismatch and severe dispersion: Existing technologies, such as traditional Mie scattering films, often exhibit significant dispersion in the visible light band, and reflectivity rapidly decreases under wide-angle incidence. This invention utilizes the Anderson localization mechanism to incoherently superimpose multiple scattering modes through a disordered structure. This disordered, ultra-uniform structure statistically eliminates directional interference, resulting in nearly flat high reflectivity across the entire 0.3–2.5 μm wavelength range, independent of the incident angle, thus achieving true wide-spectrum impedance matching.

[0044] Secondly, it resolves the paradox of mechanical compliance and functional unit load: Typically, increasing cooling power requires adding a high proportion of inorganic fillers, but this leads to material embrittlement. This invention utilizes in-situ rheological engineering to embed inorganic nanoresonators in a discrete phase within a polymer network, leveraging the porous structure generated by phase separation to buffer stress concentration. Simultaneously, the elastic modulus of the continuous polymer phase is preserved, enabling the fibers to withstand winding speeds up to 5000 m / min without breakage, thus balancing high-spectral loads with the mechanical compliance required for wearable devices.

[0045] Thirdly, this invention addresses the thermodynamic efficiency problem at the single-fiber scale: existing technologies typically require laminated films to achieve sub-environmental cooling due to the insufficient optical reflectivity of a single fiber. This invention, by constructing an overdoped photonic glass state, significantly compresses the mean free path of photons. This allows photons to undergo sufficient scattering times within a single fiber with a diameter of only tens of micrometers to trigger Anderson localization, thus achieving, for the first time in physics, steady-state sub-environmental cooling at the single-filament level. This has revolutionary implications for the breathability and lightweight properties of fabrics.

[0046] Beneficial effects:

[0047] (1) The disordered metamorphic sub-environmental radiation cooling fiber of the present invention limits the bandgap energy Eg of the inorganic nanoresonator to >3.0 eV, thereby reducing its intrinsic absorption in the visible-near-infrared main solar spectrum region and reducing photothermal conversion from the perspective of material electronic structure; at the same time, the dynamic light scattering equivalent hydrodynamic diameter of the inorganic nanoresonator is limited to 100 nm~2.5 μm, thereby forming an effective multi-scale refractive index mismatch scattering center in the 0.3~2.5 μm solar spectrum band; the coupling of the inorganic nanoresonator with high refractive index contrast and the porous structure introduces strong random fluctuations in dielectric constant inside the fiber. This disordered ultra-uniform structure causes multiple scattering of photons in the solar spectrum band (0.3~2.5 μm), resulting in the photon diffusion coefficient approaching zero, thereby triggering the Anderson localization effect; this mechanism incoherently superimposes the Mie scattering resonance, constructing an omnidirectional broadband high reflectivity barrier for ultraviolet-visible-near-infrared photons, thereby minimizing the injection of external radiative heat flow from the source.

[0048] (2) The disordered metamorphic sub-environmental radiation cooling fiber of the present invention, compared with the existing radiation cooling fibers that mainly focus on the lateral size, irregular cross section and wicking humidity regulation of inorganic micro-nano sheets, takes the band gap energy, dynamic light scattering equivalent hydrodynamic diameter and embedded continuous phase-discrete phase interface structure as the core constraints, so that the fiber's low solar absorption, high backscattering and mid-infrared high emission can be synergistically achieved at the single filament scale.

[0049] (3) The present invention provides a method for preparing disordered metamorphic sub-environmental radiation-cooled fibers. By controlling the surface charge and the steric hindrance, inorganic nano-resonators are stably embedded into the continuous phase of dielectric polymer. The method also induces the decomposition of hindered spindle lines through non-equilibrium wet spinning dynamics to construct a disordered ultra-uniform porous topological network. This method is not a simple superposition of dispersion, phase separation and freeze-drying, but rather a unified application of solution-state particle size control, interface embedding and pore freezing to the construction of photon scattering structures within the fiber. This method, without sacrificing air permeability and moisture permeability, breaks through the physical threshold of sub-environmental cooling at the single filament scale for the first time, realizing low-cost, high-throughput and continuous preparation of single fibers and fabrics.

[0050] (4) The disordered metamorphic sub-environmental radiation cooling fiber of the present invention has infrared active vibration of dielectric polymer and lattice phonon mode of inorganic nanoresonator in synergistic enhancement of thermal emission in 8~13 μm band, so that the material maintains high emissivity in the "atmospheric transparent window"; thereby, the system establishes a negative thermodynamic potential energy gradient relative to the ambient temperature, driving the heat flow to dissipate spontaneously to the low temperature cosmic background, and realizing sub-environmental cooling.

[0051] (5) The method for preparing disordered metamorphic sub-environmental radiation cooling fiber of the present invention, compared with the traditional photolithography metamaterial or multilayer film deposition technology, the present invention is based on the preparation path of wet spinning rheological engineering, which successfully solves the paradox between "precision nanophotonic structure" and "low-cost large-scale manufacturing".

[0052] (6) The application of a disordered metamorphic sub-environmental radiation cooling fiber of the present invention produces a fabric that not only has excellent radiation entropy dissipation function, but also, because the cooling function comes from the embedded photonic glass structure inside the single fiber, it does not rely on additional lamination film or surface coating, thus achieving both breathability, lightness and long-term wear comfort. Attached Figure Description

[0053] Figure 1 This is a SEM image of the fiber cross-section prepared in Example 1;

[0054] Figure 2 This is a size distribution diagram of the internal pores of the fiber prepared in Example 1;

[0055] Figure 3 A super depth-of-field image of the fabric was prepared for Example 1;

[0056] Figure 4 The spectrum of the fabric prepared in Example 1;

[0057] Figure 5 The image shows the EDS diagram of the fabric prepared in Example 1. Detailed Implementation

[0058] The present invention will be further described below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims.

[0059] The test methods involved in the performance indicators in the embodiments and comparative examples of this invention are as follows:

[0060] Bandgap energy Eg: The reflectance R of inorganic nanoresonator powder or its dried dispersion film in the range of 300~2500 nm was measured using a UV-Vis-NIR diffuse reflectance spectrometer, and the baseline was corrected using a BaSO4 standard white plate; according to the Kubelka-Munk function F(R)=(1-R). 2 Calculate the absorption correlation using (2R) and plot [F(R)hν] using the Tauc plot method. n Eg is obtained by extrapolating the linear region of the -hν curve, where n=2 is taken for materials that allow direct transitions and n=1 / 2 is taken for materials that allow indirect transitions.

[0061] Equivalent hydrodynamic diameter dH: Inorganic nanoresonators, after surface charge and steric hindrance modulation, were dispersed in the same polar aprotic solvent as the spinning solution at a concentration of 0.05–0.20 mg / mL. After sonication for 10–30 min, the Brownian diffusion coefficient D and particle size distribution were measured using dynamic light scattering (DLS) at 25 ± 1 °C. The equivalent hydrodynamic diameter was calculated according to the Stokes-Einstein equation dH = kB × T / (3π × η × D), where kB is the Boltzmann constant, T is the absolute temperature, and η is the dynamic viscosity of the solvent at the test temperature. Each sample was tested three times, and the intensity-weighted Z-average value was taken. For example, for N,N-dimethylformamide (DMF), η can be taken as 0.802 mPa·s and D = 1.21 × 10⁻⁶ at 25 °C. -12 m 2 The calculated dH value is 450 nm at / s.

[0062] Dispersion stability of the spinning solution (equivalent hydrodynamic diameter growth rate): The zeta potential of the inorganic nanoresonator in the same polar aprotic solvent was tested using a zeta potential meter; the DLS particle size was tested again after the spinning solution was allowed to stand for 24 h, and the equivalent hydrodynamic diameter growth rate was calculated as (dH,24h-dH,0h) / dH,0h×100%.

[0063] Embedding distribution and pore structure: The cross-section of the fiber and the morphology of the pore walls were observed by scanning electron microscopy, and the random embedding distribution of the inorganic nanoresonators in the dielectric polymer continuous phase was confirmed by energy dispersive spectroscopy. The pore size distribution was statistically analyzed by image analysis or mercury porosimetry.

[0064] Porosity: The porosimetry method (ISO 15901-1) was used with an AutoPore V-type mercury porosimeter, with a pressure range of 0.1 to 60,000 psi.

[0065] Solar reflectance: Measured using a UV-Vis-NIR spectrophotometer (PerkinElmer Lambda950) equipped with an integrating sphere, in accordance with ASTM E903, in the weighted AM1.5 solar irradiance spectrum in the 300–2500 nm band.

[0066] Infrared emissivity: Tested in accordance with GB / T 30127-2013 standard, using an AE1 RD1 emissivity meter, with the temperature set to the human skin temperature scale of 34~35 ℃.

[0067] Maximum temperature difference: Outdoor field test was used, with the simulated skin heat flux density set to q = 100 W / m². 2 The temperature difference ΔT between the surface temperature of the two-dimensional photonic fabric, the surface temperature of the ordinary fabric (cotton or polyester fabric), and the ambient temperature is recorded.

[0068] Breaking strength and elongation at break: measured in accordance with GB / T3923.1-2013 standard, with a tensile speed of 100 mm / min.

[0069] Example 1

[0070] A method for preparing disordered metamorphic sub-environment radiation-cooled fibers, the specific steps of which are as follows:

[0071] (1) Preparation of raw materials:

[0072] Dielectric polymer: TPU (manufacturer: Covestro, Desmopan, grade: 385E);

[0073] Inorganic nanoresonator: Al2O3;

[0074] Polar aprotic solvent: DMF;

[0075] (2) The dielectric polymer and inorganic nanoresonator were added to a polar aprotic solvent. The apparent pH of the solution was adjusted to 4.0 by adding glacial acetic acid, so that the hydroxyl groups on the Al2O3 surface were protonated and positively charged. Then, PAA (MW 5000) dispersant was added to regulate the inorganic nanoresonator so that the absolute value of the Zeta potential at 25 °C was 25.8 mV and the equivalent hydrodynamic diameter growth rate was 20% after 24 h, thus forming an isotropic spinning solution.

[0076] Among them, the inorganic nanoresonator has a mass percentage of 8% relative to the dielectric polymer; the total solid mass fraction of the dielectric polymer and inorganic nanoresonator in the spinning solution is 20%; the mass percentage of PAA relative to the dielectric polymer is 5%; the Brownian diffusion coefficient D test concentration is 0.08 mg / mL, and the test time is 20 min;

[0077] (3) The spinning solution is placed in a shear flow field and extruded through the spinneret in the wet spinning process under a pressure of 0.5 MPa. After extrusion, it enters the coagulation bath. The coagulation bath uses a mixture of deionized water and ethanol with a mass ratio of 70:30. The nascent fiber is obtained through solvent / non-solvent exchange.

[0078] The shear flow field is formed by controlling the shear stress by setting an extrusion speed of 850 m / min; the micro-orifice array of the spinneret assembly has 20 holes, and the hydraulic diameter of a single hole is 20 μm; the cross-sectional shape of the spinneret holes on the spinneret assembly is Y-shaped; the winding speed is 1500 m / min;

[0079] (4) Disordered metamorphic sub-environmental radiation-cooled fiber was obtained by freeze-drying the nascent fiber at -80 ℃ for 48 h.

[0080] The finally obtained disordered metamorphic sub-environmental radiation cooling fiber is an organic-inorganic hybrid photonic glass metamaterial with disordered ultra-uniform characteristics. It consists of a dielectric polymer as the continuous phase and inorganic nanoresonators embedded therein as the discrete phase. The band gap energy Eg of the inorganic nanoresonators is 8.2 eV, and the equivalent hydrodynamic diameter is 450 nm. The linear mass density of the disordered metamorphic sub-environmental radiation cooling fiber is 15 D, and the diameter is 0.48 mm. After fiber tensile testing, the tensile strength of the obtained disordered metamorphic sub-environmental radiation cooling fiber is 25.8 MPa, and the elongation at break is 162.5%.

[0081] Two-dimensional photonic fabrics with rough surfaces were constructed by orthogonal weaving of disordered metamorphic sub-environmental radiation-cooled fibers. The porosity of the two-dimensional photonic fabric was 42%, the solar reflectivity was 98.60%, and the infrared emissivity was 95%. The temperature of the two-dimensional photonic fabric and cotton fabric was measured simultaneously under sunlight. The temperature of the two-dimensional photonic fabric was lower than that of the cotton fabric, with a maximum temperature difference of 10 °C. In the prior art literature 1, the solar reflectivity of Nano-PE fibers was 92%, and the maximum temperature difference was 5 °C. In the literature 2, the solar reflectivity of conventional nanofiber membranes was <80%, and the maximum temperature difference was 7 °C.

[0082] like Figure 1 The image shown is a SEM cross-sectional view of the disordered metamorphic sub-environment radiation cooling fiber.

[0083] like Figure 2 As shown, the freeze-drying process suppressed the pore collapse caused by capillary forces and successfully "frozen" the porous photonic glass structure inside the fiber.

[0084] Utilizing a precision weaving dynamics system, disordered metamorphic subenvironmentally radiatively cooled fibers are used as weft resonant units to construct the fabric through an orthogonal topological interlocking process. The axial stress tensor of the warp yarns is precisely controlled to avoid surface photonic structure degradation caused by tribological damage. A shedding mechanism is used to control the warp yarn layers to establish periodic shed channels, driving the weft yarns to reciprocate, thus constructing a two-dimensional photonic crystal fabric with specific porosity and coverage factor. Its macroscopic morphology is as follows: Figure 3 As shown; the full-band spectral response is as follows Figure 4 As shown, the fabric exhibits high solar reflectance and mid-infrared emissivity, indicating a significant radiative cooling function. The EDS spectrum is shown below. Figure 5 As shown, it is demonstrated that the inorganic nanoresonators in the fiber have a random isotropic embedding distribution.

[0085] Example 2

[0086] A method for preparing disordered metamorphic sub-environment radiation-cooled fibers, the specific steps of which are as follows:

[0087] (1) Preparation of raw materials:

[0088] Dielectric polymer: TPU (manufacturer: Covestro, Desmopan, grade: 2795A);

[0089] Inorganic nanoresonator: Al2O3;

[0090] Polar aprotic solvent: DMF;

[0091] (2) The dielectric polymer and inorganic nanoresonator were added to a polar aprotic solvent, and 0.05 mol / L sodium citrate was introduced as a charge regulator. After the particles were given a high density of negative charge by adsorption, PAA (MW 10000) polymer brush was added to regulate the inorganic nanoresonator so that the absolute value of the Zeta potential at 25 °C was 26 mV and the equivalent hydrodynamic diameter growth rate was 18% after 24 h, forming an isotropic spinning solution.

[0092] Among them, the inorganic nanoresonator has a mass percentage of 30% relative to the dielectric polymer; the total solid mass fraction of the dielectric polymer and inorganic nanoresonator in the spinning solution is 45%; the mass percentage of sodium citrate relative to the dielectric polymer is 3%; the mass percentage of PAA relative to the dielectric polymer is 10%; the Brownian diffusion coefficient D test concentration is 0.1 mg / mL, and the test time is 25 min.

[0093] (3) The spinning solution is placed in a shear flow field and extruded through the spinneret in the wet spinning process under a pressure of 0.5 MPa. After extrusion, it enters the coagulation bath. The coagulation bath uses a mixture of deionized water and ethanol with a mass ratio of 90:10. The nascent fiber is obtained through solvent / non-solvent exchange.

[0094] The shear flow field is formed by controlling the shear stress by setting an extrusion speed of 1150 m / min; the micro-orifice array of the spinneret assembly has 20 holes, and the hydraulic diameter of a single hole is 20 μm; the cross-sectional shape of the spinneret holes on the spinneret assembly is trilobal; the winding speed is 3800 m / min.

[0095] The coagulation bath has a high water phase ratio of deionized water to ethanol (90:10). Due to the significant difference between the Hildebrand solubility parameter of water and that of the polymer, this highly polar environment induces transient phase separation, forming a denser skin structure on the fiber surface while retaining a highly interconnected scattering network inside.

[0096] (4) Disordered metamorphic sub-environmental radiation-cooled fiber was obtained by freeze-drying the nascent fiber at -80 ℃ for 48 h.

[0097] The finally obtained disordered metamorphic sub-environmental radiation cooling fiber is an organic-inorganic hybrid photonic glass metamaterial with disordered ultra-uniform characteristics. It consists of a dielectric polymer as the continuous phase and inorganic nanoresonators embedded therein as the discrete phase. The bandgap energy Eg of the inorganic nanoresonators is 7.9 eV, and the equivalent hydrodynamic diameter is 1.2 μm. The linear mass density of the disordered metamorphic sub-environmental radiation cooling fiber is 42 D, and the diameter is 0.32 mm. After tensile testing, the tensile strength of the obtained disordered metamorphic sub-environmental radiation cooling fiber is 14.7 MPa, and the elongation at break is 116.8%.

[0098] Two-dimensional photonic fabrics with rough surfaces were constructed by orthogonal weaving of disordered metamorphic sub-environmental radiation-cooled fibers. The porosity of the two-dimensional photonic fabrics was 72%, the solar reflectivity was 97.80%, and the infrared emissivity was 97.80%. When the two-dimensional photonic fabrics and cotton fabrics were simultaneously subjected to temperature measurements under the sun, the temperature of the two-dimensional photonic fabrics was lower than that of the cotton fabrics, with a maximum temperature difference of 12.3 ℃.

[0099] Example 3

[0100] A method for preparing disordered metamorphic sub-environment radiation-cooled fibers, the specific steps of which are as follows:

[0101] (1) Preparation of raw materials:

[0102] Dielectric polymer: TPU (manufacturer: Lubrizol, Estane, brand name: 58887);

[0103] Inorganic nanoresonator: Al2O3;

[0104] Polar aprotic solvent: DMF;

[0105] (2) The dielectric polymer and inorganic nanoresonator were added to a polar aprotic solvent, and triethylamine was added dropwise to adjust the apparent pH of the solution to 9.5. After the hydroxyl groups on the Al2O3 surface dissociated and became negatively charged, PEG (MW 2000) segments were added to regulate the inorganic nanoresonator so that the absolute value of the Zeta potential at 25 °C was 27 mV and the equivalent hydrodynamic diameter growth rate was 17.8% after 24 h, forming an isotropic spinning solution;

[0106] Among them, the inorganic nanoresonator has a mass percentage of 15% relative to the dielectric polymer; the total solid mass fraction of the dielectric polymer and inorganic nanoresonator in the spinning solution is 30%; the mass percentage of PEG relative to the dielectric polymer is 8%; the Brownian diffusion coefficient D test concentration is 0.15 mg / mL, and the test time is 20 min.

[0107] (3) The spinning solution is placed in a shear flow field and extruded through the spinneret in the wet spinning process under a pressure of 0.5 MPa. After extrusion, it enters the coagulation bath. The coagulation bath uses a mixture of deionized water and ethanol with a mass ratio of 60:40. The nascent fiber is obtained through solvent / non-solvent exchange.

[0108] The shear flow field is formed by controlling the shear stress by setting an extrusion speed of 750 m / min; the micro-orifice array of the spinneret assembly has 20 holes, and the hydraulic diameter of a single hole is 20 μm; the cross-sectional shape of the spinneret holes on the spinneret assembly is a pentagonal star; the winding speed is 750 m / min;

[0109] The coagulation bath consisted of deionized water and ethanol in a 60:40 ratio. Increasing the proportion of ethanol (a homologue of a good solvent) aimed to reduce the interfacial tension between the coagulation bath and the spinning solution, thereby slowing down the phase separation kinetics. This delayed phase separation allowed for a longer relaxation time of the polymer chains before coagulation, promoting the growth of microcrystalline regions and inducing a gradient pore structure with a wider size distribution within the fiber. This structure is beneficial for enhancing the Mie scattering efficiency in the long-wavelength band (near-infrared region) of the solar spectrum.

[0110] (4) Disordered metamorphic sub-environmental radiation-cooled fiber was obtained by freeze-drying the nascent fiber at -80 ℃ for 48 h.

[0111] The finally obtained disordered metamorphic sub-environmental radiation cooling fiber is an organic-inorganic hybrid photonic glass metamaterial with disordered ultra-uniform characteristics. It consists of a dielectric polymer as the continuous phase and inorganic nanoresonators embedded therein as the discrete phase. The band gap energy Eg of the inorganic nanoresonators is 8.6 eV, and the equivalent hydrodynamic diameter is 650 nm. The linear mass density of the disordered metamorphic sub-environmental radiation cooling fiber is 8 D, and the diameter is 0.1 mm. After tensile testing, the tensile strength of the obtained disordered metamorphic sub-environmental radiation cooling fiber is 28.7 MPa, and the elongation at break is 93.6%.

[0112] Two-dimensional photonic fabrics with rough surfaces were constructed by orthogonal weaving of disordered metamorphic sub-environmental radiation-cooled fibers. The porosity of the two-dimensional photonic fabrics was 85%, the solar reflectivity was 96.50%, and the infrared emissivity was 94.50%. When the two-dimensional photonic fabrics and cotton fabrics were simultaneously subjected to temperature measurements under the sun, the temperature of the two-dimensional photonic fabrics was lower than that of the cotton fabrics, with a maximum temperature difference of 8.8 ℃.

[0113] Example 4

[0114] A method for preparing disordered metamorphic sub-environment radiation-cooled fibers, the specific steps of which are as follows:

[0115] (1) Preparation of raw materials:

[0116] Dielectric polymer: PAN (manufacturer: Guangwei Composite Materials), grade: YWPAN-6);

[0117] Inorganic nanoresonator: ZnO;

[0118] Polar aprotic solvent: DMF;

[0119] (2) The dielectric polymer and inorganic nanoresonator were added to a polar aprotic solvent, and 0.02 mol / L tetrabutylammonium bromide (TBAB) was introduced as a background electrolyte to increase the interfacial charge density. Then, PEG (MW20000) was grafted in situ to regulate the inorganic nanoresonator so that the absolute value of the Zeta potential at 25 °C was 26.8 mV and the equivalent hydrodynamic diameter growth rate was 17.5% after 24 h, forming an isotropic spinning solution.

[0120] The inorganic nanoresonator had a mass percentage of 5% relative to the dielectric polymer; the total solid mass fraction of the dielectric polymer and inorganic nanoresonator in the spinning solution was 5%; the mass percentage of TBAB relative to the dielectric polymer was 3%; the mass percentage of PEG relative to the dielectric polymer was 3%; and the Brownian diffusion coefficient D was measured at a concentration of 0.15 mg / mL for 25 min.

[0121] (3) The spinning solution is placed in a shear flow field and extruded through the spinneret in the wet spinning process under a pressure of 0.8 MPa. After extrusion, it enters the coagulation bath. The coagulation bath uses a mixture of deionized water and ethanol with a mass ratio of 80:20. The nascent fiber is obtained through solvent / non-solvent exchange.

[0122] The shear flow field is formed by controlling the shear stress by setting an extrusion speed of 1200 m / min; the micro-orifice array of the spinneret assembly has 20 holes, and the hydraulic diameter of a single hole is 20 μm; the cross-sectional shape of the spinneret holes on the spinneret assembly is a hollow structure; the winding speed is 1200 m / min.

[0123] (4) Disordered metamorphic sub-environmental radiation-cooled fiber was obtained by freeze-drying the nascent fiber at -80 ℃ for 48 h.

[0124] The finally obtained disordered metamorphic sub-environmental radiation cooling fiber is an organic-inorganic hybrid photonic glass metamaterial with disordered ultra-uniform characteristics. It consists of a dielectric polymer as the continuous phase and inorganic nanoresonators embedded therein as the discrete phase. The band gap energy Eg of the inorganic nanoresonators is 3.37 eV, and the equivalent hydrodynamic diameter is 250 nm. The linear mass density of the disordered metamorphic sub-environmental radiation cooling fiber is 0.5 D, and the diameter is 1.85 mm. After tensile testing, the tensile strength of the obtained disordered metamorphic sub-environmental radiation cooling fiber is 20.2 MPa, and the elongation at break is 24.7%.

[0125] Two-dimensional photonic fabrics with rough surfaces were constructed by using a warp-weft interlocking process with disordered metamorphic sub-environmental radiation-cooled fibers. The porosity of the two-dimensional photonic fabric is 35%, the solar reflectivity is 95.20%, and the infrared emissivity is 92.80%. When the two-dimensional photonic fabric and cotton fabric were simultaneously subjected to temperature measurement under the sun, the temperature of the two-dimensional photonic fabric was lower than that of the cotton fabric, with a maximum temperature difference of 9.2 ℃.

[0126] Example 5

[0127] A method for preparing disordered metamorphic sub-environment radiation-cooled fibers, the specific steps of which are as follows:

[0128] (1) Preparation of raw materials:

[0129] Dielectric polymer: PVC (manufacturer: Westlake, grade: Grade 2095);

[0130] Inorganic nanoresonator: ZrO2;

[0131] Polar aprotic solvent: N-methylpyrrolidone;

[0132] (2) The dielectric polymer and inorganic nanoresonator were added to a polar aprotic solvent, and positive charge was introduced by grafting γ-aminopropyltriethoxysilane onto the ZrO2 surface using charged ligand exchange. The grafting of γ-aminopropyltriethoxysilane onto the ZrO2 surface was prepared by the method described in the reference (Facile surface tailoring of metal oxide nanoparticles via a two-step modification approach. RSC Advances, 2015, 5, 60993–61001. DOI: 10.1039 / C5RA08932H). The specific process was as follows: the nanoparticle suspension of ZrO2 in benzyl alcohol was first sonicated for 1 h, and then γ-aminopropyltriethoxysilane (APTES, Sigma-Aldrich, 741442, ≥98.0%) was added. The molar ratio of ZrO2 to APTES was 1:1, and the reaction was carried out under reflux for 12 h. h; The product was vacuum dried after being redispersed with ethanol and washed alternately with hexane;

[0133] The inorganic nanoresonator accounts for 25% of the mass of the dielectric polymer; the total solid mass fraction of the dielectric polymer and inorganic nanoresonator in the spinning solution is 60%; and the ZrO2 surface grafted with γ-aminopropyltriethoxysilane accounts for 3% of the mass of the dielectric polymer.

[0134] (3) After introducing positive charge in step (2), PVP (MW 40000) adsorption layer is added to regulate the inorganic nanoresonator so that the absolute value of the Zeta potential at 25 °C is 28 mV and the equivalent hydrodynamic diameter growth rate is 17% after 24 h, forming an isotropic spinning solution.

[0135] The mass percentage of PVP relative to the dielectric polymer was 5%; the Brownian diffusion coefficient D was tested at a concentration of 0.18 mg / mL for 20 min.

[0136] (4) The spinning solution is placed in a shear flow field and extruded through the spinneret in the wet spinning process at a pressure of 1.2 MPa. After extrusion, it enters a deionized water coagulation bath and obtains nascent fibers through solvent / non-solvent exchange.

[0137] The shear flow field is formed by controlling the shear stress by setting an extrusion speed of 700 m / min; the micro-orifice array of the spinneret assembly has 20 holes, and the hydraulic diameter of a single hole is 20 μm; the cross-sectional shape of the spinneret holes on the spinneret assembly is a four-leaf shape; the winding speed is 700 m / min;

[0138] (5) Disordered metamorphic sub-environmental radiation-cooled fiber was obtained by freeze-drying the nascent fiber at -80 ℃ for 48 h.

[0139] The finally obtained disordered metamorphic sub-environmental radiation cooling fiber is an organic-inorganic hybrid photonic glass metamaterial with disordered ultra-uniform characteristics. It consists of a dielectric polymer as the continuous phase and inorganic nanoresonators embedded therein as discrete phases. The band gap energy Eg of the inorganic nanoresonators is 5.2 eV, and the equivalent hydrodynamic diameter is 850 nm. The linear mass density of the disordered metamorphic sub-environmental radiation cooling fiber is 55 D, and the diameter is 1.92 mm. Tensile testing of the fiber shows that the breaking strength of the obtained disordered metamorphic sub-environmental radiation cooling fiber is 6.5 MPa, and the elongation at break is 38.5%.

[0140] Two-dimensional photonic fabrics with rough surfaces were constructed by using a warp-weft interlocking process with disordered metamorphic sub-environmental radiation-cooled fibers. The porosity of the two-dimensional photonic fabrics was 65%, the solar reflectivity was 95.90%, and the infrared emissivity was 93.90%. When the two-dimensional photonic fabrics and cotton fabrics were simultaneously subjected to temperature measurements under the sun, the temperature of the two-dimensional photonic fabrics was lower than that of the cotton fabrics, with a maximum temperature difference of 8.5 ℃.

[0141] Example 6

[0142] A method for preparing disordered metamorphic sub-environment radiation-cooled fibers, the specific steps of which are as follows:

[0143] (1) Preparation of raw materials:

[0144] Dielectric polymer: PPTA derivative (manufacturer: DuPont, brand name: Kevlar-29);

[0145] Inorganic nanoresonator: BaSO4 and SiO2 in a mass ratio of 1:1;

[0146] Polar aprotic solvent: DMSO;

[0147] (2) The dielectric polymer and inorganic nanoresonator were added to a polar aprotic solvent. The solvent-intrinsic 5wt% LiCl was used as the background electrolyte. After adjusting the apparent pH to 9.0 with ammonia, sodium polyacrylate (MW of 10000 Da) molecular brushes were grafted onto the surface to control the inorganic nanoresonator so that the absolute value of the Zeta potential at 25 °C was 28 mV and the equivalent hydrodynamic diameter growth rate was 16.7% after 24 h, forming an isotropic spinning solution.

[0148] Among them, the inorganic nanoresonator has a mass percentage of 50% relative to the dielectric polymer; the total solid mass fraction of the dielectric polymer and inorganic nanoresonator in the spinning solution is 60%; the sodium polyacrylate molecular brush has a mass percentage of 3% relative to the dielectric polymer; the Brownian diffusion coefficient D test concentration is 0.2 mg / mL, and the test time is 25 min.

[0149] (3) The spinning solution is placed in a shear flow field and extruded through the spinneret in the wet spinning process under a pressure of 2.5 MPa. After extrusion, it enters the coagulation bath. The coagulation bath uses a mixture of deionized water and ethanol with a mass ratio of 50:50. The nascent fiber is obtained through solvent / non-solvent exchange.

[0150] The shear flow field is formed by controlling the shear stress by setting an extrusion speed of 1050 m / min; the micro-orifice array of the spinneret assembly has 20 holes, and the hydraulic diameter of a single hole is 20 μm; the cross-sectional shape of the spinneret holes on the spinneret assembly is fan-shaped; the winding speed is 1050 m / min.

[0151] (4) Disordered metamorphic sub-environmental radiation-cooled fiber was obtained by freeze-drying the nascent fiber at -80 ℃ for 48 h.

[0152] The finally obtained disordered metamorphic sub-environmental radiation cooling fiber is an organic-inorganic hybrid photonic glass metamaterial with disordered ultra-uniform characteristics. It consists of a dielectric polymer as the continuous phase and inorganic nanoresonators embedded therein as discrete phases. The band gap energy Eg of BaSO4 in the inorganic nanoresonators is 5.9 eV, and the band gap energy Eg of SiO2 is 8.8 eV. The equivalent hydrodynamic diameter of BaSO4 is 100 nm, and the equivalent hydrodynamic diameter of SiO2 is 2.5 μm. The linear mass density of the disordered metamorphic sub-environmental radiation cooling fiber is 25 D, and the diameter is 0.3 mm. After tensile testing, the tensile strength of the obtained disordered metamorphic sub-environmental radiation cooling fiber is 49.2 MPa, and the elongation at break is 17.9%.

[0153] Two-dimensional photonic fabrics with rough surfaces were constructed by using a warp-weft interlocking process with disordered metamorphic sub-environmental radiation-cooled fibers. The porosity of the two-dimensional photonic fabric was 58%, the solar reflectivity was 98.90%, and the infrared emissivity was 96.60%. When the two-dimensional photonic fabric and cotton fabric were simultaneously subjected to temperature measurement under the sun, the temperature of the two-dimensional photonic fabric was lower than that of the cotton fabric, with a maximum temperature difference of 13.2 ℃.

Claims

1. A disordered metamorphic sub-environmental radiation cooling fiber, characterized in that: It is an organic-inorganic hybrid photonic glass metamaterial with disordered and ultra-uniform characteristics, consisting of a dielectric polymer as a continuous phase, a discrete-phase inorganic nanoresonator embedded in situ and confined by the continuous phase, and a porous scattering network fixed by non-solvent phase separation and freeze-drying. The inorganic nanoresonator is a three-dimensional micro / nano particle with a random isotropic embedded distribution within the radial cross section of the fiber, forming a multi-scale refractive index mismatch scattering center between air, dielectric polymer and inorganic nanoresonator. The bandgap energy of the inorganic nanoresonator is Eg>3.0 eV; the dynamic light scattering equivalent hydrodynamic diameter of the inorganic nanoresonator is 100 nm~2.5 μm.

2. The disordered metamorphic sub-environmental radiation cooling fiber according to claim 1, characterized in that, The dielectric polymer is selected from block copolymer thermoplastic polyurethane, polyacrylonitrile, polyvinyl chloride, poly(p-phenylene terephthalamide) and its derivatives.

3. The disordered metamorphic sub-environmental radiation cooling fiber according to claim 1, characterized in that, The inorganic nanoresonator is selected from one or more of the following: corundum phase alumina, wurtzite zinc oxide, monoclinic zirconium oxide, tantalum pentoxide, barite-type barium sulfate, amorphous or crystalline silicon dioxide, and silicon nitride.

4. The disordered metamorphic sub-environmental radiation cooling fiber according to claim 1, characterized in that, The inorganic nanoresonator has a mass percentage of 5-50% relative to the dielectric polymer.

5. The disordered metamorphic sub-environmental radiation cooling fiber according to claim 1, characterized in that, The linear mass density of the disordered metamorphic subenvironmental radiation cooling fiber is 0.5~55 D, and the diameter is 0.01~2 mm.

6. A method for preparing a disordered metamorphic sub-environmental radiation-cooled fiber as described in any one of claims 1 to 5, characterized in that: First, a dielectric polymer and an inorganic nanoresonator are added to a polar aprotic solvent. Through surface charge regulation and the combined effect of steric hindrance generated by the polymer adsorption layer or molecular brush, the absolute value of the zeta potential of the inorganic nanoresonator at 25±1 °C is not less than 25 mV, and the equivalent hydrodynamic diameter growth rate after 24 h is not more than 20%, forming an isotropic spinning solution. Then, the spinning solution is placed in a shear flow field and extruded through a wet spinning process, followed by non-solvent-induced phase separation to induce the formation of nascent fibers. Finally, the nascent fibers are freeze-dried to fix the pore network and embedded inorganic nanoresonator distribution formed by phase separation, thus producing disordered metamorphic subenvironmental radiation-cooled fibers.

7. The method for preparing a disordered metamorphic sub-environmental radiation-cooled fiber according to claim 6, characterized in that, The shear flow field is formed by controlling the shear stress by setting an extrusion speed of 700~1200 m / min.

8. The method for preparing a disordered metamorphic sub-environmental radiation-cooled fiber according to claim 6, characterized in that, Non-solvent phase separation induced molding refers to the process where the spinning solution is extruded through the spinneret and enters the coagulation bath, which uses a mixture of deionized water and ethanol, and the solution is exchanged with the nascent fiber through solvent / non-solvent exchange.

9. The method for preparing a disordered metamorphic sub-environmental radiation-cooled fiber according to claim 8, characterized in that, The cross-sectional shape of the spinneret orifice on the spinneret assembly is one or more of the following: Y-shaped, pentagonal, trilobal, quadrilobal, pentlobal, fan-shaped, and hollow structure.

10. The method for preparing a disordered metamorphic sub-environmental radiation-cooled fiber according to claim 6, characterized in that, The total solid mass fraction of the electropolymer and inorganic nanoresonator in the spinning solution is 5-100%.

11. The application of a disordered metamorphic sub-environmental radiation cooling fiber as described in any one of claims 1 to 5, characterized in that: Two-dimensional photonic fabrics with rough surfaces are constructed by using disordered metamorphic sub-environment radiation-cooled fibers through orthogonal weaving or warp-weft interlocking processes.

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