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Semi‐rigid polyurethane foams (SPUF) with high deformation resistance and strength are indispensable for cushioning applications. However, for high fire risk and cascaded pollutant effects, overused multifarious additives and foam wastes exacerbate global environmental concerns. One option to address this issue is to develop eco‐friendly multifunctional flame retardants that participate in the material lifecycles of preparation, safe service, waste management, and sustainable recycling. Herein, a novel self‐adaptive catalytic strategy is reported that exploits the temperature and agent structure‐responsive catalytic ability of eco‐friendly sodium propionate (SP), reconciling the often‐conflicting properties of fabrication and recycling while effectively mitigating combustion risks and additive pollution. The adaptive catalytic function of SP impressively involves all aspects of foam life cycles: 1) catalyzing foaming without complex/hazardous catalysts; 2) providing superior flame‐retardant efficiency with a high limiting oxygen index of 25.5% without relying on traditional flame retardants; 3) promoting in situ network fragmentation and reorganization into strong adhesives (5.8 MPa); and 4) further recycling of the newly formed adhesives in a self‐driven sustainable manner. A novel green strategy is presented that addresses fire hazards, plastic pollution, and the unsustainability of recycling, minimizing the ecological risks of foam, which will positively impact future sustainable material design involving diverse additives. [ABSTRACT FROM AUTHOR]

Highlights: Inspired by the photoreception mechanisms of urchins, the urchin-like Ti3C2Tx@ZnO hollow spheres are rationally designed as high-performance microwave absorbents by constructing ZnO nanoarrays onto the surface of Ti3C2Tx hollow spheres. Both experimental and theoretical simulation results demonstrate that the microstructure of urchin-like possesses giant advantages in electromagnetic wave absorption performance, which is superior to most absorbers with similar components. Ingenious microstructure design and rational composition selection are effective approaches to realize high-performance microwave absorbers, and the advancement of biomimetic manufacturing provides a new strategy. In nature, urchins are the animals without eyes but can "see", because their special structure composed of regular spines and spherical photosensitive bodies "amplifies" the light-receiving ability. Herein, inspired by the above phenomenon, the biomimetic urchin-like Ti3C2Tx@ZnO hollow microspheres are rationally designed and fabricated, in which ZnO nanoarrays (length: ~ 2.3 μm, diameter: ~ 100 nm) as the urchin spines are evenly grafted onto the surface of the Ti3C2Tx hollow spheres (diameter: ~ 4.2 μm) as the urchin spherical photosensitive bodies. The construction of gradient impedance and hierarchical heterostructures enhance the attenuation of incident electromagnetic waves. And the EMW loss behavior is further revealed by limited integral simulation calculations, which fully highlights the advantages of the urchin-like architecture. As a result, the Ti3C2Tx@ZnO hollow spheres deliver a strong reflection loss of − 57.4 dB and broad effective absorption bandwidth of 6.56 GHz, superior to similar absorbents. This work provides a new biomimetic strategy for the design and manufacturing of advanced microwave absorbers. [ABSTRACT FROM AUTHOR]

This study establishes a three-dimensional model of the heat and mass transfer for the drying of a sea cucumber. The heat pump drying experiment was designed to verify the numerical simulation results. The simulated values are consistent with the experimental values regarding the dry base moisture content and temperature change trend. The maximum average deviation rate of the moisture content did not exceed 10%, and the maximum temperature deviation did not exceed 3°C. The simulation results show that the dry base moisture content of the sea cucumber increases from the surface to the internal area of the sea cucumber under different drying temperatures, whereas the temperature decreases from the surface to the internal area. The surface temperature of the sea cucumber gradually increased as the drying progressed until the end, when it was slightly lower than the inlet temperature. The time to reach the inlet temperature decreased with increasing inlet wind speed. The uniformity of the drying equipment was enhanced by setting the air supply parameters of the floor nozzle. [ABSTRACT FROM AUTHOR]

To understand the thermal characteristics of carbon fiber heating wires, we tested the heating rules of carbon fiber heating wires with inner core tows of 12k and 24k and different lengths. We found that the surface temperature of the carbon fiber heating wires rose and fell quickly when the power supply was turned on and off by 82.9 and 18.3°C/min, respectively. After the quick rise period, the surface temperature tended to be steady with ±2°C of fluctuation; the steady temperature decreased as the length increased. With an increase in the length from 7 to 12 m, the steady temperature of the 12k and 24k wires reduced from 122°C and 166°C to 53°C and 71°C, respectively. Using the COMSOL Multiphysics software to simulate the carbon fiber heating wires, the simulated surface temperatures were in good agreement with the experimental results, with errors less than 7%. The convective and radiative heat transfer of the simulated carbon fiber electric heating wire decreased with an increase in length and the number of tows, and the convective heat transfer was much higher than the radiative heat transfer to indicate that the convective heat transfer is the main heat transfer mode in the heat dissipation of the carbon fiber electric heating wire. Results indicate that there is a rapid increase in temperature when power is on, and thereafter temperature remains constant. These are the important characteristics of carbon fiber heating wires. [ABSTRACT FROM AUTHOR]

Abstract In an effort to overcome issues encountered in additive flame retardants for rigid polyurethane foams (RPUFs), a novel reactive flame-retardant triol (TDHTPP) based on a triazine and phosphate structure was designed and synthesized. This triol was chemically incorporated in the main chains of RPUFs as a chain-extender to prepare inherently flame-retardant RPUFs. TDHTPP showed good solubility in the polyols (polyol 4110 and PEG 400) of RPUF, making it convenient for industrial fabrication, such as in spay foaming. Excellent compatibility of TDHTPP with the polymer matrix endowed flame-retardant RPUFs (FR-RPUFs) much higher compressive strength than that of the neat RPUF, and a low thermal conductivity of ∼0.03 W/(m·K). Notably, with only 5 wt% of TDHTPP incorporated, the resultant RPUF displayed a UL-94 V-0 rating and more importantly, exhibited a great persistent flame retardancy during thermal accelerated aging tests at 140 °C for 96 h. Further characterization revealed that TDHTPP possessed both vapor-phase and condensed-phase flame-retardant behaviors, in which, vapor-phase action was dominant. This work provides a facile route to synthesize RPUFs with persistent flame retardancy, excellent thermal insulation and mechanical properties. Graphical abstract Image 1 Highlights • A novel reactive retardant THDTPP was designed to prepare inherently flame-retardant RPUFs. • Great compatibility of TDHTPP with matrix endows FR-RPUFs with excellent thermal insulating and mechanical properties. • The persistent flame retardancy of these foams was confirmed by thermal aging tests. • These foams with excellent properties show a promising prospect in the field of building thermal insulation. [ABSTRACT FROM AUTHOR]

A novel Co@crystalline carbon@carbon aerogel composite with yolk-shell structure was fabricated via a green and facile method using biomass-based alginate aerogels as precursor. In the resultant composite, a large amount of highly crystallized Co nanoparticles (∼41.5 wt%) with a diameter of 5–20 nm was coated with crystalline carbon layer and evenly embedded in the porous carbon aerogel matrix. Due to core-shell Co@crystalline carbon structure, the thermal oxidation stability of the composite can be significantly improved. The porous composite also had the high surface area (425 cm 3 g −1 ) and showed considerable magnetization. Benefitting from the well-designed constitution and structure, the Co@crystalline carbon@carbon aerogel composite showed great microwave absorption performances. When the filler loading of the composite in wax was only 10 wt% and the thickness of the absorber was as thin as 1.5 mm, the maximum RL reached −43 dB. The excellent microwave absorption performances with low filler loading and ultrathin thickness make the aerogel composite show great potential application in the microwave absorption field. [ABSTRACT FROM AUTHOR]

Poly(ethylene terephthalate) (PET) is a fiber-forming polymer with the largest output and widest usage. Its flame retardation is well-achieved via a mechanism of promoting the melt dripping while ignited. However, the melt dripping leads to secondary damage and an immediate empyrosis during fire. How to address the contradiction between the flame retardation and the melt-dripping behavior of PET via an inherent flame-retardant approach becomes a real challenge. This feature article highlights the design and synthesis of novel PET-based copolyesters with flame-retardant and antidripping performance. Three approaches are used to design these copolyesters: 'ionic aggregation,' 'smart self-cross-linking,' and 'rearrangement at high temperatures.' Some new conceptions are proposed accordingly. The synthesis, structure characterization, and properties of those copolyesters are discussed together with the ongoing challenges and limitations at this frontier. [ABSTRACT FROM AUTHOR]

Several kinds of novel flame-retardant-free and thermo-crosslinkable epoxy resins (EPs) containing azobenzene or/and phenylacetylene groups have been synthesized and characterized, and the flame retardant properties as a result of thermal crosslinking during combustion were investigated in detail. Crosslinking behaviors were tested by simultaneous thermogravimetry–differential scanning calorimetry (TGA–DSC). Thermal stabilities were investigated by thermogravimetric analysis (TGA). Flame retardance of the resulting EPs was evaluated through LOI tests, and combustion behaviors were studied via cone calorimetry and micro-combustion calorimetry (MCC), which further confirmed that flame retardance of these EPs was significantly improved, despite the absence of conventional flame retardant. Py–GC/MS analysis was used to investigate the degradation mechanism of these epoxy resins, and the results confirmed that the flame-retardant activity of epoxy resins mainly took effect in the condensed phase. The chemical constitution of the char layers were investigated by XPS and Raman spectrum. The co-crosslinking behavior between azobenzene and phenylacetylene groups was predicted and confirmed, which led to the most compact char layer, therefore resulted in the best flame retardance of these EPs. [ABSTRACT FROM AUTHOR]

Clay membrane hybrid composites wereprepared by facile solution-castingof aqueous precursor suspensions of poly(vinyl alcohol) (PVOH) andmontmorillonite clay (MMT), then cross-linked by gamma irradiation.The influences of absorbed dose and polymer loading on composite structureand properties were investigated. A moderate amount of PVOH (P4C6)is found to be optimum for fabricating mechanically strong PVOH composites;however, gamma irradiation has a positive influence on strengtheningcomposites only with low PVOH content. Scanning electron microscopy(SEM) observation shows a layered structure from the cross-sectionof a cryo-fractured surface for all composites, and a comparativelysmooth surface. The wide-angle X-ray diffraction (WAXD) characterizationshows an intercalated MMT structure with incorporation of PVOH. Cross-linkingand the increase of clay content lead to a decreased onset decompositiontemperature but an increase in the temperature at the maximum decompositionrate and enhancement of the residue of the resulting materials. Theclay membranes possess very low flammability, which is not significantlyinfluenced by gamma irradiation. [ABSTRACT FROM AUTHOR]

A self-cross-linkable poly(ethylene terephthalate) block copolyester (SSP-PETPx) has been synthesized via solid-state polymerization (SSP). In the SSP process, a cross-linkable monomer named 4-(phenylethynyl) di(ethylene glycol) phthalate (PEPE) is incorporated into the amorphous phase of PET. The sequence distribution of the resulted copolyester SSP-PETPx is analyzed with 1 H NMR, showing that the SSP sample possesses block structure. Wide-Angle X-ray diffraction (WAXD) and differential scanning calorimetry (DSC) show that SSP-PETPx is crystallizable benefitting from its block structure, while the corresponding random copolyester (RD-PETP) is totally amorphous. The segments containing PEPE determine the extent of crystallization. Simultaneous thermogravimetric-differential scanning calorimetry (TG-DSC) and rheological analysis prove the cross-linking behaviour of SSP-PETP although the block constitution slightly postpones cross-linking occurrence. The high complex viscosity of the SSP-PETP at 340 °C suggests good flame retardancy and anti-dripping properties. Micro combustion calorimeter (MCC) results prove both SSP-PETP and RD-PETP copolyesters have low flammability, which demonstrates that block structure of SSP-PETP doesn't have a negative impact on the flammability of copolyesters. [ABSTRACT FROM AUTHOR]

A new nanocomposite, poly(aniline- co-diphenylamine-4-sulfonic acid)/graphene (PANISP/rGO), was prepared by means of an in situ oxidation copolymerization of aniline (ANI) with diphenylamine-4-sulfonic acid (SP) in the presence of graphene oxide, followed by the chemical reduction of graphene oxide using hydrazine hydrate as a reductant. The morphology and structure of PANISP/rGO were characterized by field-emission (FE) SEM, TEM, X-ray photoelectron spectroscopy (XPS), Raman, FTIR, and UV/Vis spectra. The electrochemical performance was evaluated by cyclic voltammetry, galvanostatic charge-discharge, and electrochemical impedance spectroscopy. The PANISP/rGO nanocomposite showed a nanosized structure, with sulfonic polyaniline nanoarrays coated homogeneously on the surface of graphene nanosheets. This special structure of the nanocomposite also facilitates the enhancement of the electrochemical performance of the electrodes. The PANISP/rGO nanocomposite exhibits a specific supercapacitance up to 1170 F g−1 at the current density of 0.5 A g−1. The as-prepared electrodes show excellent supercapacitive performance because of the synergistic effects between graphene and the sulfonic polyaniline copolymer chains. [ABSTRACT FROM AUTHOR]

[Display omitted] • A formaldehyde-free and effective flame-retardant coating is developed for EPS foams. • The coating can tightly bind the EPS beads, leading to enhanced mechanical strength and durable thermal insulation. • The resultant EPS composite shows excellent flame-retardant and smoke-suppressant performances. • The flame-retardant and smoke-suppressant mechanism is investigated in detail. Expandable polystyrene (EPS) foam, one of the most widely used thermal insulation of building materials, is highly flammable, while its traditional flame-retardant coating has been severely restricted by the low efficiency and the use of toxic formaldehyde adhesive. Herein, we demonstrate a formaldehyde-free phosphorus-containing polysiloxane coating that acts as both an adhesive and a flame retardant for EPS foams. In this design, on one hand, the high adhesion of the polysiloxane can evenly and tightly bind the EPS beads and expandable graphite (EG, a flame-retardant synergist filler) at a relatively low additive loading, thus leading to durable thermal insulation even under high humidity conditions. On the other hand, the functional coating can promote the formation of P/Si-containing graphited char layers during the combustion of the EPS composite, which can effectively isolate oxygen, heat, combustible compounds, and smoke particles. As a result, the EPS composite showed excellent flame retardancy with a high limiting oxygen index of 36%, a UL-94V-0 rating, and a significantly reduced peak heat release rate (−76%), while the smoke release can be greatly suppressed both in cone calorimetry and smoke density tests. This work provides a new strategy for the design of environmentally friendly coatings, which can give EPS foam high fire safety and excellent comprehensive performance. [ABSTRACT FROM AUTHOR]

Oxygen carrier (OC) particles for chemical-looping combustion (CLC) may be produced in large scale by a number of methods such as freeze granulation, spray drying, impregnation, and mechanical mixing methods. To select the most appropriate technology for large-scale preparation, the four preparation methods were adopted to prepare Fe2O3/Al2O3 OCs and compared with each other in terms of productivity, preparation period, physical and chemical characterization, and reactivity in CLC of lignite. Freeze granulation and spray drying methods were found to be more suitable for large-scale production of OCs for CLC. The results of the comparative studies may provide guidelines for selecting appropriate methods for preparing OCs on industrial scale. [ABSTRACT FROM AUTHOR]

Abstract: Flame-retardant-free and thermo-cross-linkable copolyesters have been synthesized, and their flame retardation and anti-dripping behavior as a consequence of cross-linking during combustion were investigated in detail. TG-DSC simultaneous thermal analysis, rheological analysis, and TGA established the extent and rate of the cross-linking reaction. The extent of cross-linking depends on the content of cross-linkable monomer, PEPE, and the higher the extent of the cross-linking, the better the flame retardance and anti-dripping performance of copolyesters. The large melt viscosity caused by cross-linked networks at high temperature played the most important role in anti-dripping of copolyesters. TG-FTIR results confirmed that the flame-retardant activity of copolyesters mainly took effect in the condensed phase, and XPS results indicated that the carbonization process was aromatization-dominant. SEM and Raman analysis suggested that the char layers were constituted mainly of polyaromatic species with small and uniform microstructures at the surface. Consequently, both the large melt viscosity and the formation of an especially compact char with fine microstructure resulting from cross-linking were considered as the key to the flame retardance and anti-dripping performance of the polymer when subjected to the flame. [Copyright &y& Elsevier]

We report the design of three frequency selective surface (FSS) filters used on the FengYun-4 (FY-4) microwave satellite, which separate five-frequency bands in the frequency range of 50-429 GHz with the insertion loss less than 0.4 dB, and separation between adjacent channels more than 20 dB for either TE or TM incidence. Firstly, we briefly introduce the disadvantages of two types of FSS filter: waveguide-array FSS and printed FSS, which are commonly employed in the millimeter and sub-millimeter wave band. In order to meet the insertion loss requirement and specified spectral transmission response, we adopt a filter composed of two closely spaced freestanding metal plates, which contains an array of resonant ring slot elements. Computer simulation technology (CST) is used to optimize the structural dimensions of the resonant unit and interlayer separation. Numerical results show that these FSS filters exhibit transmission loss of less than 0.4 dB and separation between adjacent channels of more than 20 dB. Simulated transmission coefficients are in close agreement with the required specification, and even exceed the performance specifications. [ABSTRACT FROM AUTHOR]

The density functional and ab initio theory were used to investigate the second-order nonlinear optical (NLO) properties of Schiff base ligands, open-shell Fe(III), and closed-shell Ni(II) complexes. The effect of the metal center in complexes is thus manifold: it templates the formation of acentric structures, imparts high thermal stability to the chelate ring, and display higher second-order NLO response than their ligands. The second-order NLO response of metal complexes are intensively sensitive to the exchange donor/acceptor because the differences of the extent of charge separation and the intraligand charge transfer processes. Thus, substituted metal complexes could realize “switches on” the second-order NLO response by exchange donor/acceptor. © 2009 Wiley Periodicals, Inc. Int J Quantum Chem, 2010 [ABSTRACT FROM AUTHOR]

The time evolution of aerosol size distribution during precipitation, which is founded mathematically by general dynamic equation (GDE) for wet removal, describes quantitatively the process of aerosol wet scavenging. The equation depends on aerosol size distribution, raindrop size distribution and the complicated model of scavenging co-efficient which is induced by taking account of the important wet removal mechanisms such as Brownian diffusion, interception and inertial impaction. Normal numerical methods can hardly solve GDE, which is a typical partially integro-differential equation. A new multi-Monte Carlo method was introduced to solve GDE for wet removal, and then was used to simulate the wet scavenging of aerosols in the real atmospheric environment. The results of numerical simulation show that, the smaller lognormal raindrop size distribution and lognormal initial aerosol size distribution, the smaller geometric mean diameter or geometric standard deviation of raindrops can help scavenge small aerosols and intermediate size aerosols better, though large aerosols are prevented from being collected in some ways. [ABSTRACT FROM AUTHOR]

Monte-Carlo (MC) method is widely adopted to take into account general dynamic equation (GDE) for particle coagulation, however popular MC method has high computation cost and statistical fatigue. A new Multi-Monte-Carlo (MMC) method, which has characteristics of time-driven MC method, constant number method and constant volume method, was promoted to solve GDE for coagulation. Firstly MMC method was described in details, including the introduction of weighted fictitious particle, the scheme of MMC method, the setting of time step, the judgment of the occurrence of coagulation event, the choice of coagulation partner and the consequential treatment of coagulation event. Secondly MMC method was validated by five special coagulation cases in which analytical solutions exist. The good agreement between the simulation results of MMC method and analytical solutions shows MMC method conserves high computation precision and has low computation cost. Lastly the different influence of different kinds of coagulation kernel on the process of coagulation was analyzed: constant coagulation kernel and Brownian coagulation kernel in continuum regime affect small particles much more than linear and quadratic coagulation kernel, whereas affect big particles much less than linear and quadratic coagulation kernel. [ABSTRACT FROM AUTHOR]

Carbon materials play a pivo tal role across various advanced applications, yet their synthesis traditionally necessitates inert atmospheres to avert oxidation at high temperatures, thus inflating production costs and resource utilization. Achieving precision synthesis of functional porous carbon materials via air‐pyrolysis remains a formidable challenge. Herein, a streamlined, one‐step lava‐like carbonization approach is introduced enabling the fabrication of porous carbons boasting tailored morphologies (0‐3D), elevated specific surface areas (540.7–1047.6 m2g⁻¹), heteroatom doping, and commendable carbon yields (20‐39.1%) through direct pyrolysis within an air environment. Leveraging recyclable boric acid as a reaction medium, a lava‐like flowing protective barrier above 170 °C is engendered that spontaneously creates an oxygen‐free‐like milieu devoid of high pressure or intricate procedures. This boron‐containing lava serves dually as a template and chemical activator, facilitating pore formation and catalyzing porous carbon production. Notably, the method accommodates a spectrum of carbon sources, encompassing sugars, proteins, graphene oxide, and their metal mixtures. The resultant morphologically customizable carbons exhibit excellent performance in areas as diverse as microwave absorption and electrocatalysis. This work pioneers a novel pathway for large‐scale precision synthesis of high‐quality carbon materials via air‐pyrolysis under mild conditions. [ABSTRACT FROM AUTHOR]

Oriented aerogels, emerging as a new generation of lightweight electromagnetic interference (EMI) materials, often face complex synthesis processes. While creating an orderly oriented microstructure for EMI aerogels through ambient pressure drying (APD) shows promise, it remains a significant challenge. Here, inspired by the directional grown structure of the plant, a new strategy that employs rapid precursor orientation followed by slow cross‐linking to achieve the APD of directional EMI aerogels is proposed. This approach demonstrates that low‐temperature oriented polymerization of polyaniline enables strong cross‐linking with poly(3,4‐ethylenedioxythiophene) and alginate, forming a robust conductive directional skeleton and mitigating surface tension issues during mild drying. The resulting aerogel features high conductivity (48.84 S m−1), excellent flame retardancy, and impressive compressive strength. Notably, its sturdy frame allows for further enhancement with other functional materials, such as Mxene, through re‐processing and re‐drying. The tree‐branch‐like aerogel achieves a significantly improved EMI shielding effectiveness of 50.3 dB across an ultrawideband range of 8.2–40 GHz. This strategy offers a new idea for the straightforward preparation of functional aerogels with programmability and oriented microstructures using ambient drying. [ABSTRACT FROM AUTHOR]

A tridimensional turbulent flow model is established for a closed heat pump drying system with waste heat recovery to improve the drying air flow characteristics and reduce the energy consumption of air circulation. The active flow distribution mode is introduced to guide air flowing in the system's drying cabinet, top air duct, mixing zone, and heat pump. It is found that the wind velocity in the cabinet's supply channel is greater than that in the return channel, the velocity distribution in the top duct is uneven, and the outlet velocity of the bypass fan is high and a vortex forms. A partition panel added in the top duct and modulating fans in the drying cabinet are proposed to solve these problems. The simulation results show that removing the circulating fan, changing the volume flow of the bypass fan, adopting the alternative operation mode of the bypass fans, reducing the air volume flow of the supply fan, and reducing the total pressure of the fans can improve the dry air velocity uniformity in the drying cabinet and reduce the energy consumption of the fans. This paper analyzes the closed-loop drying air flow characteristics of the active flow distribution system in the heat pump drying system, which lays a foundation for the wind velocity, temperature, and humidity regulating of heat pump drying system with waste heat recovery. [ABSTRACT FROM AUTHOR]

To compare the different actions of the two representative transition metal cations of Co2+ and Ni2+ in layered double hydroxides (LDHs), CoAl-LDH and NiAl-LDH intercalated with CO32− were synthesized, and the chemical structures, microstructures, and surface areas thereof were successfully characterized. Then, the two LDHs were utilized as flame retardants and smoke suppressants for silicone foam (SiF). The densities, flame retardancy, smoke suppression, thermal stabilities, and compressive strengths of the two SiF/LDHs nanocomposites were investigated. The introduction of LDHs slightly decreased the density of SiF due to the catalytic actions of Co and Ni during the foaming process of SiF. With respect to the flame retardancy, the addition of only 1 phr of either CoAl-LDH or NiAl-LDH could effectively improve the limiting oxygen index of SiF from 28.7 to 29.6%. Based on the results of vertical flame testing and a cone calorimeter test, the flame retardancy and fire safety of the SiF were effectively enhanced by the incorporation of LDHs. In addition, owing to the good catalytic action and large specific surface area (NiAl-LDH: 174.57 m2 g−1; CoAl-LDH: 51.47 m2 g−1), NiAl-LDH revealed higher efficiencies of flame retardancy and smoke suppression than those of CoAl-LDH. According to the results of energy-dispersive X-ray spectroscopy, Co and Ni participated in the formation of protective char layers, which inhibited the release of SiO2 into the gas phase. Finally, the influences on the thermal decomposition and compressive strength for SiF resulting from the addition of LDHs are discussed. [ABSTRACT FROM AUTHOR]

• An eco-friendly biomass-based flame-retardant coating was developed to cotton fabrics. • The coating neither used elements such as Cl, Br, P nor organic solvents. • The coating exhibited excellent durability due to the action like dyestuff fixing. • The flame-retardant mechanism of the coating was revealed in detail. Inspired by the classic dye-fixing process, a novel eco-friendly biomass-based coating that neither used traditional elements such as Cl, Br, P nor toxic organic solvents was first developed to endow cotton fabrics with durable flame retardancy from biomass tannin (TA), tartar emetic (TE), and Fe2+. In this coating system, TA used as a charring agent was fixed onto the fiber surface of cotton fabric by TE in water via the action like dyestuff fixing, while Fe2+ coordinated with the hydroxyl of TATE can catalyze TA and cotton fibers to form graphited stable carbon residues for achieving high flame retardance. Consequently, the resultant fabrics showed great flame retardance with excellent durability. Even after 100 laundering or friction cycles, their limiting oxygen index values of ~27.0% hardly changed. And the washed flame-retardant cotton fabrics still easily passed the horizontal flammability test with an extremely low destroy spread speed. Moreover, scanning electron microscopy, confocal laser scanning microscope, and cone calorimeter test results all confirmed the durability of the coating. The flame-retardant mechanism analysis demonstrated that the coating could promote the cotton fibers to form dense and regular graphitized carbon layers and effectively protect the matrix from decomposing to flammable gases under high temperatures. In addition to durable flame retardancy, the mechanical properties and hydrophilicity of cotton were slightly influenced by the flame-retardant coating. This eco-friendly biomass-based flame-retardant coating provides a new strategy for fabricating green flame-retardant systems without using hazardous compounds. [ABSTRACT FROM AUTHOR]

Conventional methods to improve the flame retardancy of polymeric materials usually involve the use of flame-retardant elements such as Cl, Br and P, however, their use may bring more smoke and toxic gases hazards, and more importantly, cause non-negligible environmental and ecological problems. In this work, we put forward a novel green strategy that eliminates the use of any conventional flame-retardant elements to improve the flame retardancy by incorporating a synergistically cross-linkable structure (named PN) containing phenylacetylene and phenylimide groups. The resulting PN copolymer exhibited an excellent 55% lower smoke release rate and 68% lower heat release rate than the pure polymer, as well as a high LOI value of 32% and UL-94 V-0 rating with excellent anti-dripping performance. TG-DSC, rheological and FTIR results proved the high cross-linking ability of the PN copolymer due to the synergistic cross-linking effect between the "imide-isoimide" rearrangement of phenylimide and the "self-cross-linking" of phenylacetylene. The SEM, Raman and Py-GC/MS results further upheld the condensed phase flame-retardant mechanism. This eco-friendly synergistic cross-linking strategy provided new perspective for the design and synthesis of polymeric materials with excellent flame retardancy, great anti-dripping performance, and low release of heat, smoke, and toxic gas. Image 1 • An eco-friendly flame-retardant strategy was developed to improve the flame retardancy and suppress the smoke release. • This green strategy did not use any conventional halogen and phosphorus flame-retardant elements. • The resultant polymer showed excellent anti-dripping performance and significant suppression of heat, smoke, toxic gas. • The flame-retardant mechanism was revealed in detail. [ABSTRACT FROM AUTHOR]

Porous carbon materials with multiscale distinctive morphologies hold significant promise in electromagnetic wave stealth/protection and catalysis; however, formidable challenges are highly verbose and resource/time-consuming fabrication processes. Here, we report a one-step solvent/template-free self-expanding carbonization strategy for rapidly fabricating porous carbon foams (Ni/CNT) with zero-dimensional (0D) nanoparticles, one-dimensional (1D) nanotube forests, and three-dimensional (3D) hollow microvesicles. Owing to the multi-morphological structure and low-density feature, the resulting porous carbon foam Ni/CNT-800 achieves a minimum reflection loss of −56.48 dB and an effective bandwidth of 5.44 GHz at a low filler loading of only 9 wt%. Moreover, altering the electronic structure and surface chemistry of carbon foam by phosphorus doping enables a highly reduced durable overpotential (η) of 275 mV for oxygen evolution reaction. This work emphasizes a straightforward strategy for the facile design and efficient fabrication of carbon-based materials with unique multiscale porous morphologies, customizable functions, and various applications. A green solvent/template-free self-expanding carbonization strategy enables the one-step fabrication of multi-morphological porous carbon foams with 0D nanoparticles, 1D nanotube forests, and 3D hollow microvesicles without additional chemical reagent consumption and complex operation. The resulting Ni/CNT foams exhibit customizable functions and highly effective electromagnetic wave absorption at a low loading of only 9 wt% and impressive durable oxygen evolution activity with an η 10 of 275 mV, which is promising for electromagnetic wave stealth/protection and renewable energy applications. [Display omitted] • A solvent/template-free and one-step self-expanding carbonization strategy is demonstrated to fabricate multi-morphological porous carbon foams with 0D nanoparticles, 1D carbon nanotube forests, and 3D hollow microvesicles. • Porous carbon foams exhibit excellent minimum reflection loss of −56.48 dB and effective absorption bandwidth of 5.44 GHz at a low filler loading of 9 wt%. • A highly improved durable overpotential (η) of 275 mV can be achieved by facile phosphorus modification, revealing the unique customizable and versatile function of carbon foams. [ABSTRACT FROM AUTHOR]

Passive radiative cooling is a zero‐energy technology vital for mitigating the energy crisis. However, achieving intelligent thermal management across varying weather conditions (day/night and summer/winter) while maintaining sustainability is a significant challenge. Here, a recyclable biomass film engineered for adaptive, year‐round energy conservation is introduced. This film utilizes porous acetyl cellulose (AC) as a cooling‐side matrix, enabling efficient radiative cooling during hot days (8.5 °C reduction) and minimizing overcooling on cold nights (only 2.5 °C reduction). This performance is facilitated by high solar reflectance (96.3%) and broad‐spectrum infrared emission (95.4%), optimizing atmospheric thermal regulation. The reverse side, coated with carbon black (CB), demonstrates superior solar heating (20.9 °C increase), allowing for effortless switching between cooling and heating by flipping the film. Further, the film employs a solvent‐responsive ethyl cellulose (EC) adhesion, ensuring durability, complete recycling, and reuse. With ultraviolet (UV) resistance, self‐cleaning, and durability, coupled with intelligent thermal management, this work provides new ideas for advanced radiative heat management materials, enabling adaptive control during both daytime/nighttime and summer/winter. [ABSTRACT FROM AUTHOR]

Wood, a readily available and sustainable natural resource, has found widespread use in construction and furniture. However, its inherent flammability poses a potential fire risk. Although intumescent fire-retardant coatings effectively mitigate this risk, achieving high transparency in such coatings presents a significant challenge. In our approach, we employed a cross-linked network of phytic acid anion and N-[3-(trimethoxysilyl) propyl]-N,N,N-trimethylammonium cation to create a transparent "three-in-one" intumescent coating. The collaborative P/N/Si flame-retardant effect markedly improved the intumescent char-forming capability, preventing the wood from rapid decomposition. This resulted in a substantial reduction in heat release (13.9% decrease in THR) and an increased limiting oxygen index (LOI) value of 35.5%. Crucially, the high transparency of the coating ensured minimal impact on the wood's appearance, allowing the natural wood grains to remain clearly visible. This innovative approach provides a straightforward method for developing transparent intumescent flame-retardant coatings suitable for wooden substrates. The potential applications extend to preserving ancient buildings and heritage conservation efforts. [ABSTRACT FROM AUTHOR]

The MADS-box gene family encodes transcription factors and plays an important role in plant growth and the development of flower and fruit. A perennial dioecious plant, the red bayberry genome has been published recently, providing the opportunity to analyze the MADS-box gene family and its role in fruit development and ripening. Here, we identified 54 MADS-box genes in the red bayberry genome, and classified them into two types based on phylogenetic analysis. Thirteen Type I MADS-box genes were subdivided into three subfamilies and 41 Type II MADS-box genes into 13 subfamilies. A total of 46 MADS-box genes were distributed across eight red bayberry chromosomes, and the other eight genes were located on the unmapped scaffolds. Transcriptome analysis suggested that the expression of most Type II genes was higher than Type I in five female tissues. Moreover, 26 MADS-box genes were expressed during red bayberry fruit development and ten of them showed high expression. qRT-PCR showed that the expression of MrMADS01 (SEP , MIKC C ), with differences between the pale pink and red varieties, increased significantly at the final ripening stage, suggesting it may participate in ripening as positive regulator and related to anthocyanin biosynthesis. These results provide some clues for future study of MADS-box genes in red bayberry, especially in ripening process. • 54 MADS-box genes were identified in the red bayberry genome, including 13 Type I genes and 41 Type II genes. • Expression of most Type II MADS-box genes was higher than Type I in five female tissues. • Ten MADS-box genes were highly expressed during red bayberry fruit development, and MrMADS01 was related to fruit color. [ABSTRACT FROM AUTHOR]

Aerogels, the lightest solids with practicable mechanical properties and functionality, are rapidly expanding the family members and applications these years. The reason can be attributed to the simple and green preparation by freeze casting (FC) method and the excellent properties of the resultant materials. Although inorganic aerogels, metal aerogels, polymer aerogels and composite aerogels towards different goals, such as thermal isolation, sensors, electromagnetic interference shielding, absorbent, separation, life science, supercapacitor, catalysis, etc., have been fabricated by this methodology, the definition and influence factors during the FC process are not clarified in the literature and become a remarkable bottleneck for further development. This review differentiates three different types of freeze. And for the FC type, it collects the scattered factors in literature that influence the microstructure of aerogels and makes combinations and comments between the microstructure and the resulting performances. Three kinds of FC methods, i.e. traditional unidirectional freezing casting (UFC), recent bidirectional freeze casting (BFC) and orthogonal freeze casting (OFC), are clarified. We hope this review contribute the development of FC method and design of novel aerogels. [ABSTRACT FROM AUTHOR]

High‐performance thermal insulating aerogels are attractive candidates for thermal protection in extreme environments. However, inorganic aerogels' brittleness and poor machinability limit their applications, while organic aerogels suffer from severe strength degradation and structural collapse at high temperatures. Herein, for the first time, a thermo‐responsive self‐ceramifiable aerogel is demonstrated with exceptional strengthening and thermal insulation at high temperatures. This aerogel exhibits excellent toughness and processability like polymers under normal conditions but spontaneously transforms into high‐strength semi‐crystalline hard ceramics upon exposure to high temperatures. After prolonged thermal attack at 800 °C, the strength of the aerogels does not decrease but significantly increases several‐fold (from 0.739 to 2.726 MPa). The self‐ceramization behavior and mechanism of the aerogel are illustrated in detail. The unique self‐ceramifiable capacity enables aerogels to provide fire resistance, high‐strength support, and excellent thermal insulation at ultrahigh temperatures. Even with continuous burning at 1300 °C for 60 min, the 15 mm thick aerogel shows low backside temperature below 300 °C, crack‐free overall structure, and invariant porous morphology. This self‐ceramifiable aerogel opens up a new avenue for developing thermal‐protection materials with toughness, machinability, high strength, and thermal insulation in extreme environments. [ABSTRACT FROM AUTHOR]

[Display omitted] • The combination of the inorganic structure with the flexible aliphatic segment was proposed to fabricate P-decorated POSS. • Epoxy resins with P-decorated POSS maintained high transparency. • The resultant P-decorated POSS showed both high flame retardancy and mechanical reinforcement for epoxy resins. • The specific mechanism of action was analyzed. Epoxy resins (EPs) are known for their durability, strength, and adhesive properties, which make them a versatile and popular material for use in a variety of applications, including chemical anticorrosion, small electronic devices, etc. However, EP is highly flammable due to its chemical nature. In this study, phosphorus-containing organic–inorganic hybrid flame retardant (APOP) was synthesized by introducing 9, 10-dihydro-9-oxa-10‑phosphaphenathrene (DOPO) into cage-like octaminopropyl silsesquioxane (OA-POSS) via Schiff base reaction. The improved flame retardancy of EP was achieved by combining the physical barrier of inorganic Si-O-Si with the flame-retardant capability of phosphaphenanthrene. EP composites containing 3 wt% APOP passed the V-1 rating with a value of LOI of 30.1% and showed an apparent reduction in smoke release. Additionally, the combination of the inorganic structure and the flexible aliphatic segment in the hybrid flame retardant provides EP with molecular reinforcement, while the abundance of amino groups facilitates a good interface compatibility and outstanding transparency. Accordingly, EP containing 3 wt% APOP increased in tensile strength, impact strength, and flexural strength by 66.0 %, 78.6 %, and 32.3 %, respectively. The EP/APOP composites had a bending angle lower than 90°, and their successful transition to a tough material highlights the potential of this innovative combination of the inorganic structure and the flexible aliphatic segment. In addition, the relevant flame-retardant mechanism revealed that the APOP promoted the formation of a hybrid char layer containing P/N/Si for EP and produced phosphorus-containing fragments during combustion, showing flame-retardant effects in both condensed and vapor phases. This research offers innovative solutions for reconciling flame retardancy & mechanical performances and strength & toughness for polymers. [ABSTRACT FROM AUTHOR]

Natural textiles are ubiquitous and irreplaceable in daily life but suffer from their inherent flammability, which poses a substantial threat to property and life safety in the event of fire. Flame-retardant protective coatings are widely regarded as an efficacious means to address this problem. However, most conventional flame-retardant coatings often appear opaque or dark in color. Herein, we report a transparent and environment-friendly flame-retardant coating via a facile one-pot sol-gel strategy derived from diphenylphosphinic acid (DPPA) and 3-aminopropyltriethoxysilane (APTES). In this system, the homogeneous three-dimensional cross-linked polysiloxane-based network leads to a high light transmittance of 98 % in the visible region. Meanwhile, the resultant coating exhibits robust interfacial adhesion and great applicability to fabric substrates. Remarkably, the synergistic effect between phosphorus (P), nitrogen (N) and silicon (Si) endows the coating with a clearly visible char-forming capacity, which further imparts excellent flame retardancy to both cotton and silk fabrics, featuring a desired LOI value, self-extinguish behavior and low heat release. This work provides a fresh perspective on the design of universal flame-retardant coating, particularly integrating the virtues of environment friendliness, transparency, and colorlessness. [Display omitted] • An environment-friendly transparent and universal flame-retardant coating was developed for natural fabrics. • The coating displayed excellent transparency with a light transmittance as high as 98 % in the visible region. • The coating exhibited exceptional flame retardancy for cotton and silk fabrics simultaneously. • The flame-retardant mechanism of the coating was clarified in detail. [ABSTRACT FROM AUTHOR]

To address the current development requirements for multifunctional cotton fabrics, a phytic acid-induced flame-retardant hydrophobic coating containing nitrogen (N), phosphorus (P), and silicon (Si) was grafted on the surface of cotton fabrics using a facile step-by-step immersion method. The limiting oxygen index value improved to 31.2 %, decreasing to 26.7 % after 50 laundering cycles, while the fabric remained self-extinguishing effect in the vertical flammability test and showed a water contact angle of 126.1°. Cone calorimetry test showed that the modified fabric could not be ignited at the irradiation heat flux of 35 kW/m2. When the irradiation heat flux was raised to 50 kW/m2, there was a significant decline in the peak heat release rate of the modified cotton fabric, which decreased by 43.2 % to a remarkably low value of 114.0 kW/m2, indicating excellent flame-retardant properties. The analysis of the flame-retardant mechanism uncovered that the modified coating exhibited a significant dual flame-retardant mechanism involving both the gaseous phase and the condensed phase. Additionally, the oil-water separation tests revealed that the separation efficiency of the modified cotton fabrics was as high as 97.1 % and remained around 96 % after 10 cycles, which made them reusable for the clean-up of hazardous chemicals. • A bio-based flame-retardant hydrophobic coating for cotton fabric was developed by a simple immersion method. • The modified cotton fabrics still exhibited self-extinguishing properties even after 50 cycles of washing. • The modified cotton fabrics show outstanding oil-water separation capabilities with an efficiency reaching 97.1 %. • The relevant flame-retardant mechanism was detailed analyzed. [ABSTRACT FROM AUTHOR]

Three polyaniline/graphene oxide (PANI/GO) composites were fabricated by means of an in-situ polymerization of aniline monomers in the presence of graphene oxide (GO). And then, nitrogen-doped graphene was prepared by pyrolysis of the PANI/GO composite. The structures and morphologies of the samples were characterized by using different techniques, and the electrochemical performances of the nitrogen-doped graphene samples were further investigated. When PANI/GO10 (the GO feed content in PANI/GO is 10 wt.%) was used as a precursor, and the pyrolysis temperature is 800 °C, nitrogen content of the as-prepared nitrogen-doped graphene (i.e., NG10-800) is 9.2 at.%. The specific capacitance of NG10-800 is up to 206 F g −1 at a current density of 1 A g −1 , indicating an excellent electrochemical performance. After 1000 cycles at a scan rate of 50 mV s −1 , the capacitance retention of NG10-800 is about 92.5% of the initial value, suggesting an excellent cycling stability. [ABSTRACT FROM AUTHOR]

[Display omitted] • An interfacial hollow engineering strategy was proposed to fabricate nanohybrid flame retardants. • Bio-based phytic acid was assembled into the hollow cavity of mesoporous SiO 2 grafted with polydopamine-transition metal. • The resultant nanohybrid showed both high flame retardancy and mechanical reinforcement for epoxy resin. • The specific mechanism of action was analyzed. Nano flame retardants, as one of the key flame retardants in recent years, have been limited by poor efficiency and weak compatibility. In this study, we propose an interfacial hollow engineering strategy to tackle this problem by assembling P-phytic acid into the hollow cavity of mesoporous SiO 2 grafted with a polydopamine transition metal. In this design, the grafted polydopamine-metal coatings on the hybrids can greatly improve their interface compatibility with the polymer matrix, while the loaded phytic acid in the cavity contributes to enhance flame retardancy. Consequently, the resultant hierarchical P-loaded nanohybrids show both high flame retardancy and mechanical reinforcement for the polymer. Taking epoxy resin (EP, a typical thermosetting resin used in large quantities) as a representative, at only 1 wt% loading of the nanohybrids, the impact strength of the nanocomposites improved by 35.7% compared to pure EP. Remarkably, the hybrids can simultaneously endow EP with high flame retardancy (low heat release rate) and satisfactory smoke inhibition. Additionally, the flame-retardant mechanism analysis confirmed that the nanohybrid had a better catalytic carbonization effect on promoting the highly graphitized carbon layer, thereby suppressing the fire hazard of epoxy resins. This research offers a new interfacial hollow engineering method for the construct and design of high-performance EP with nanohybrids. [ABSTRACT FROM AUTHOR]

[Display omitted] • An interfacial hollow engineering strategy was proposed to fabricate nanohybrid flame retardants. • Bio-based phytic acid was assembled into the hollow cavity of mesoporous SiO 2 grafted with polydopamine-transition metal. • The resultant nanohybrid showed both high flame retardancy and mechanical reinforcement for epoxy resin. • The specific mechanism of action was analyzed. Nano flame retardants, as one of the key flame retardants in recent years, have been limited by poor efficiency and weak compatibility. In this study, we propose an interfacial hollow engineering strategy to tackle this problem by assembling P-phytic acid into the hollow cavity of mesoporous SiO 2 grafted with a polydopamine transition metal. In this design, the grafted polydopamine-metal coatings on the hybrids can greatly improve their interface compatibility with the polymer matrix, while the loaded phytic acid in the cavity contributes to enhance flame retardancy. Consequently, the resultant hierarchical P-loaded nanohybrids show both high flame retardancy and mechanical reinforcement for the polymer. Taking epoxy resin (EP, a typical thermosetting resin used in large quantities) as a representative, at only 1 wt% loading of the nanohybrids, the impact strength of the nanocomposites improved by 35.7% compared to pure EP. Remarkably, the hybrids can simultaneously endow EP with high flame retardancy (low heat release rate) and satisfactory smoke inhibition. Additionally, the flame-retardant mechanism analysis confirmed that the nanohybrid had a better catalytic carbonization effect on promoting the highly graphitized carbon layer, thereby suppressing the fire hazard of epoxy resins. This research offers a new interfacial hollow engineering method for the construct and design of high-performance EP with nanohybrids. [ABSTRACT FROM AUTHOR]

• Novel NiTi-LDH nanosheet was designed as an effective flame-retardant and smoke-suppressor. • NiTi-LDH nanosheet possessed an average thickness of 1.93 ± 0.02 nm and large specific surface areas. • 1 phr NiTi-LDH endowed silicone foam with outstanding flame retardancy and smoke suppression. • Highly efficient flame retardant silicone foam without halogen and phosphorus. There is a need for further enhancing fire safety of silicone foam (SiF) due to its popularization and application in aircraft and the latest generation of high-speed train. We prepared a novel NiTi-layered double hydroxide nanosheets (NiTi-LDH) by a co-precipitation method, which was used as highly effective flame-retardant and smoke-suppressor for SiF. FTIR and X-ray photoelectron spectrometerwere conducted to analyze the chemical structure of NiTi-LDH. The microstructure and crystal phase of NiTi-LDH were determined by scanning electron microscope (SEM), X-ray diffraction (XRD), and transmission electron microscopy. The results of atomic force microscope and Brunauer-Emmett-Teller analyses demonstrated that NiTi-LDH possessed an ultra-thin structure with an average thickness of 1.93 ± 0.02 nm and large specific surface areas (194.4 m2 g−1). After being evaluated by vertical flame testing (UL-94), limiting oxygen index (LOI), and cone calorimeter test, only 1.0 phr NiTi-LDH made SiF pass UL-94 V-0 rating with an increased LOI (28.7–30.3%), and greatly inhibited smoke release compared to untreated silicone foam. Meanwhile, both the maximum smoke density and smoke density rank of SiF/NiTi-LDH-1.0 are lower than those of SiF. To further understand the flame retardant action of NiTi-LDH, we used thermogravimetric analysis (TGA), XRD and FTIR to investigate its thermal decomposition behavior, the evolutions of chemical/crastal structures during heating. X-ray energy dispersive spectroscopy coupled with SEM (SEM-EDS) and TGA-FTIR were adopted to analyze the char residue and gaseous products. NiTi-LDH exhibited possible catalytic actions for high efficiency smoke suppression and flame retardancy based on char-forming and flammable volatiles inhibition in both the condensed and gaseous phase. [ABSTRACT FROM AUTHOR]

Atmospheric drying method for fabricating aerogels is considered the most promising way for casting aerogels on a large scale. However, the organic solvent exchange, remaining environmental pollution risk, is a crucial step in mitigating the impact of surface tension during the atmospheric drying process, especially for wet gel formed through the alkoxy-derived sol-gel process, such as melamine-formaldehyde resin (MF) aerogel. Herein, a tough polymer-assisted in situ polymerization was proposed to fabricate MF resin aerogel with a combination of mechanical toughness and strength, enabling it to withstand the capillary force during water evaporation. The monolithic MF resin aerogel through the sol-gel method can be directly prepared without additional network strengthening or organic solvent exchange. The resulting MF resin aerogel exhibits a homogeneous as well as hierarchical structure with macropores and mesopores (~6 μm and ~5 nm), high compressive modulus of 31.8 MPa, self-extinguishing property, and high-temperature thermal insulation with 97 % heat decrease for butane flame combustion. This work presents a straightforward and environmentally friendly method for fabricating MF resin aerogels with nanostructures and excellent performance in open conditions, exhibiting various applications. • A tough biomass-assisted in situ polymerization is proposed for the fabrication of melamine-formaldehyde (MF) resin aerogel via the atmospheric drying method. • Benefiting from the robust cross-linking networks and homogeneous porous structures, the MF resin aerogel displayed a modulus of 31.8 MPa. • The MF resin aerogel exhibits superior flame retardance with a limiting oxygen index value of 35.5% and high temperature insulation. [ABSTRACT FROM AUTHOR]

Polymers are widely used in our daily life; however, most of them are highly flammable. Once modified with flame retardants (FRs), polymers always have deteriorative properties in mechanical strength aspects. As a countermeasure, a novel unified phosphorus and nitrogen-containing organic nano-layered flame retardant (BA-MA) was synthesized by the assembly of biphenyl-4,4′-diphosphonic acid (BA) and melamine (MA), which was used as an additive flame retardant for polystyrene (PS) resin. The chemical structure and morphology of BA-MA were characterized, and a possible growth mechanism of the nanolayered structure was presented in detail. The resulting BA-MA with a thickness of about 60 nm can be uniformly dispersed in the PS resin, thus maintaining the mechanical properties of the material. Remarkably, under only 1 wt% loading of BA-MA, the flammability of PS can be largely reduced with a 68% reduction in the peak heat release rate. Additionally, the smoke release was also significantly inhibited. The research on flame retardant mechanisms shows that BA-MA mainly produces incombustible gas to dilute the concentration of combustibles and promote the formation of aromatic carbon layers to isolate oxygen transmission and heat transfer. [ABSTRACT FROM AUTHOR]

A new method for characterizing fiber bending flexibility was developed by worm-like chain model proposed by Kratky-Porod,[1] which was first introduced to the pulp and paper field in this study. For the three types of pulps, the experimental results were compared with the KP chain model, and the resulting determination coefficients were all above 0.95, which proved that the model was feasible to be applied to these three fibers. The relation between fiber bending rigidity and that of cellulosic chains inside was discussed to deduce the fiber bending flexibility. The flexibility of an individual fiber can be approximated as the contribution of that of all the cellulose chains inside. By this method, the fiber flexibility values were determined to be in the range of 0.6×1011−3.5×1011 N−1·m−2, which was comparable to that of the conventional methods recorded in the literature. [ABSTRACT FROM AUTHOR]

Abstract: A series of intumescent flame-retardant epoxy resins (IFR-EPs) were prepared only by adding a 5wt% total loading of ammonium polyphosphate (APP) and metal compounds. All the samples could achieve V-0 rating and did not generate dripping during UL-94 testing. The limiting oxygen index (LOI) values of the samples with 4.83wt% APP and 0.17wt% CoSA increase from 27.1 to 29.4, compared with epoxy resin containing 5wt% APP. The samples also showed excellent water resistance of flame retardancy in 30°C and 70°C water for 168h. The LOI results show that the composition of metal compounds (metal ions and ligands/anions) and the mass ratios of APP to metal compounds affect the flame retardancy of the samples. TG results indicate that the catalytic effect of CoSA on the decomposition of both APP and the epoxy resins containing APP is better than that of CuSAO. The fire behavior of epoxy resin and epoxy resins containing APP with/without CoSA were investigated by cone calorimeter. Cone calorimeter parameters of the samples such as HRR, THR, TSP and COP indicate that the addition of APP and CoSA improves the fire safety of epoxy resin significantly, and CoSA shows an obvious catalytic effect. [Copyright &y& Elsevier]

Nowadays, there is an urgent need for microwave absorbing materials with light weight, thin thickness, and strong absorbing ability to solve the problem of electromagnetic radiation. In this study, we report a novel high-performance aerogel absorber by growing MoO 3 -doped WO 3 nanoflakes on reduced graphene oxide (rGO) sheets. The resultant rGO-Mo-WO 3 aerogel displays a low density (∼75 mg/cm3) and unique hierarchical architectures including 3D porous microstructures, 2D rGO skeleton, and binary transition metal oxide of Mo-WO 3 nanoflakes, thus leading to excellent microwave absorption performances. Typically, rGO-Mo-WO 3 aerogel exhibits an ultra-strong reflection loss (RL) of −61.8 dB with a thin coating thickness of 1.54 mm. And a wide effective absorption bandwidth of 6.24 GHz can be achieved at a low filler loading of 8 wt%, much superior to previous ones. The synergistic effect of moderate polarization relaxation loss and weak conduction loss together with the porous microstructure for the aerogel result in the suitable impedance matching and strong microwave attenuation ability. This work may demonstrate a promising method to fabricate hierarchically nanostructured absorbers with the advantages of light weight, ultra-strong microwave absorption, and thin coating thickness. [Display omitted] • A functional aerogel is fabricated by growing MoO 3 -doped WO 3 nanoflakes on rGO sheets. • The aerogel with low density and unique hierarchical architectures displays excellent microwave absorption. • An ultra-strong reflection loss of −61.8 dB is achieved at a thin thickness of 1.54 mm. • A wide effective absorption bandwidth of 6.24 GHz is achieved at an ultra-low filler loading of 8 wt%. • The microwave absorption mechanism of the aerogel is proposed in detail. [ABSTRACT FROM AUTHOR]

Here, a novel multifunctional coating containing bio-based phytic acid (PA), L-glutamic acid (L-Glu), and trimesoyl chloride (TMC) is constructed by a simple soaking strategy, giving cotton fabrics excellent flame retardancy, washability, and antibacterial properties. The coating layer on the cotton surface was prepared via the electrostatic and hydrogen bonding between PA and L-Glu, accompanied by the interface polymerization between PA, L-Glu, and TMC. Among them, the limiting oxygen index value of the treated cotton fabrics (C 2 and C 2 -TMC) was as high as 40 %. During the vertical flammability test, both C 2 and C 2 -TMC cotton showed self-extinguished behavior with a short damaged length (≤50 mm). Remarkably, the LOI of C 2 -TMC sustained a high value (30 %) even after 300 laundering cycles, maintaining its self-extinguishing behavior in the vertical combustion test. Additionally, in the cone calorimetry test, peak heat release rate and total heat release of treated cotton were lower than control cotton. Surprisingly, after 30 or 60 laundering cycles, the C 2 -TMC cotton exhibited excellent antibacterial activity against Escherichia coli , Staphylococcus aureus , and Candida albicans due to the continuous exposure of PA and L-Glu. Moreover, the coating layer on the cotton surface had little impact on the mechanical properties and feel of the fabric. • Bio-based coating based on phytic acid and L-glutamic acid was constructed on cotton fabrics by simple immersion method. • The treated cotton fabrics exhibited excellent flame-retardant and antimicrobial properties. • The treated cotton fabrics displayed satisfactory abrasion resistance and laundering durability. • C 2 -TMC cotton still exhibited excellent antibacterial activity against E. coli , S. aureus , and C. albicans. [ABSTRACT FROM AUTHOR]

Constructing thermally cross-linkable structures into thermoplastic polymers has emerged as a compelling strategy to enhance flame retardancy. However, the cross-linking reactions are hard to control, leading unexpected deterioration of processability and mechanical properties. Here, we report a novel strategy to modulate cross-linking reactions utilizing intramolecular hydrogen bonding and steric hindrance effects. Taking aromatic Schiff base (SA) as an example, novel monomers SAP and SAPN were designed and synthesized by incorporating phenolic and naphthalene units. As expected, the resultant copolymer PET- co -SAPN n exhibited a 120 °C higher cross-linking temperature compared with that of PET- co -SA n , powering them with great processability. Robust mechanical properties were obtained owing to the enhanced polymerization stability and intramolecular hydrogen bonding of SAPN, as evidenced by the tensile strength of 86.0 MPa for PET- co -SAPN 15 , 1.6 times to that of pure PET. Additionally, PET- co -SAPN n exhibits the highest fire safety, whose peak heat release rate (pHRR) and maximum smoke density (D m) decreased by 49% and 53%, attributing to enhanced char-forming ability from the cross-linking and the phenolic and naphthalene units in SAPN. Considering these adequate improvements, this study provides a novel strategy for designing "self-cross-linking" flame-retardant polymers with improved processability and fire-safety. [Display omitted] • Tailoring cross-linking reactions via hydrogen bonding and steric hindrance. • Broadened processing window achieved with Schiff base-functionalized monomer SAPN. • Improved processability and mechanical properties due to enhanced polymerization quality. • Enhanced fire safety through rapid cross-linking and efficient char formation. [ABSTRACT FROM AUTHOR]

[Display omitted] • The amalgamation of a phosphorus-containing diol with ammonium polyphosphate to fabricate phosphorus-hybridized silica aerogel. • The resultant hybrid silica aerogel showed both high flame retardancy and mechanical reinforcement for RPUF. • The specific flame-retardant mechanism was analyzed. Due to the wide application of rigid polyurethane foam (RPUF) in the fields of building structural materials and thermal insulation materials, the development of high-performance RPUF composites with exceptional flame retardancy, smoke suppression, and mechanical properties is of paramount importance. In this study, we present an approach involving the amalgamation of a phosphorus-containing diol with ammonium polyphosphate to fabricate phosphorus-hybridized silica aerogel (P-SiA). The unique dual hydroxyl configuration of DDP exhibits a remarkable reactivity with silica sol, thereby facilitating the effective dispersion of APP within the silica sol. Additionally, the polyhydroxyl structure within the P-SiA enhance its compatibility with the RPUF. The compressive strength of RPUF/P-SiA-5 increased by approximately 46.4% in comparison to pristine RPUF. Furthermore, in contrast to pristine RPUF, the thermal insulation effect of RPUF/P-SiA composites were further enhanced. In addition, the effective integration of two distinct phosphorus-containing compounds in P-SiA effectively enhances the flame retardancy of RPUF composites, as substantiated by the achievement of a limiting oxygen index value of 23.2% for RPUF/P-SiA-15. Besides, relative to RPUF containing pure silica aerogel, both heat release and smoke release of RPUF/P-SiA composites are effectively suppressed. The implications of these findings propose a new strategy of tailoring material interactions and optimizing composite formulations to obtain the high-performance RPUF composites, which has a broad application prospect. [ABSTRACT FROM AUTHOR]

A low‐profile omnidirectional antenna based on folded Alford loop is proposed for wireless body area network (WBAN) applications in industrial, scientific, and medical (ISM, 2.4‐2.4835 GHz and 5.725‐5.875 GHz) bands. By fabricating two complementary symmetrically folded Alford loops on both sides of a round Roger substrate, the proposed antenna has small volume and omnidirectional radiation capability in both bands. Since the omnidirectional radiation plane is parallel to the human body surface, low specific absorption rate (SAR) can be obtained. The proposed antenna has a profile of 0.639 mm and occupies an area of π × 302 mm2, along with a measured peak gain of 6.1 dBi and 14.1% impedance bandwidth (BW) at 2.45 GHz and peak gain of 2.2 dBi and 6.7% impedance BW at 5.8 GHz. Simulated and measured results reveal that the antenna has good omnidirectional radiation in both bands. Moreover, the bending sensitivity study and SAR analysis prove that it is a good candidate for wearable WBAN devices. [ABSTRACT FROM AUTHOR]

This letter proposes an implantable planar inverted‐F antenna for biotelemetry applications, which operates at 2.4 GHz‐2.48 GHz industrial, scientific, and medical band. The antenna is miniaturized by loading a shorting metal surface between the radiating patch and the ground. Moreover, biocompatible substrate‐superstrate layers are used to achieve low specific absorption rate (SAR). We study the performance of antennas at different implant depths. The simulated and measured results show the proposed antenna has higher realized gain of −4.5 dB at 2.45 GHz. The impedance bandwidth (−10 dB) of 180 MHz (2.34 GHz‐2.52 GHz) can be obtained. Moreover, this antenna has a lower SAR value of 113.5 W/kg for a 1‐g standard, which satisfies the regulations in the IEEE standard. [ABSTRACT FROM AUTHOR]

• Novel aerogels with chemically and physically double cross-linked networks were fabricated. • The aerogel showed ultrahigh compressive modulus of 41.9 MPa. • The aerogel maintained high modulus at high temperatures. • The aerogel showed excellent fire resistance and high-temperature thermal insulation. Aerogels with low density and excellent thermal insulation are seriously plagued by poor mechanical properties with low compressive moduli in the kPa range, especially in extreme conditions such as high temperatures and fires. In this work, a new double chemical cross-linking and physical cross-linking strategy is developed to synthesize ultrahigh-modulus aerogels with extreme-condition resistance from low-cost polyvinyl alcohol (PVA), bio-based phytic acid (PA) and montmorillonite (MMT). The resultant aerogels consist of interpenetrating networks with chemically cross-linked domains between PVA and PA and physically cross-linked domains among PVA, PA and MMT, leading to an ultrahigh compressive modulus of 41.9 MPa and a specific modulus of 455.4 MPa·cm3·g−1, which can even withstand a car crush. Benefitting from the formation of ultra-strong network backbones containing phosphorus and clay, the aerogels amazingly show excellent fire resistance and high-temperature thermal insulation features. This robust porous material can maintain its structural integrity and high modulus (~2 MPa) after exposure to extremely high-temperature flame (~1300 °C), and also exhibits high mechanical modulus of ~4 MPa after heating treatment at 900 °C. These special characteristics make the aerogel a promising insulation candidate in the fields of aviation, aerospace and other applications. [ABSTRACT FROM AUTHOR]