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Using layer‐by‐layer self‐assembly technology, an intelligent nano‐coating was constructed on melamine foam (MF) by electrostatic interactions between chitosan (CS) molecules and graphene oxide (GO) nano‐sheets. According to the principle that GO is quickly reduced to reduced GO under high temperature, a fast fire‐warning network can be constructed. Due to the protective effect of nano‐coating constructed on MF, the thermal stability and flame retardancy of melamine composite foams are improved. As the nano‐coating self‐assembly layer increases to 20, its flame‐response time is only 3 s, and the continuous alarm time is as high as 1280 s. These indicate that the prepared GO‐CS composite foam possesses excellent flame retardancy and super‐fast fire response. This study provides a novel idea for the application of bio‐based nano‐coating in the fire early response and warning. [ABSTRACT FROM AUTHOR]

Due to the energy‐saving demands in chemical industries and building fields, thermal isolation materials (TIMs) are widely used. The general exploitation of combustible TIMs calls for timely fire alerts as well as flame‐retardant modifications. This work provides a novel paradigm to address the issues simultaneously by preparing a multifunctional aerogel via a facile and environmentally friendly freeze‐drying method. With the doping of ammonium polyphosphate and graphene oxide (GO), cellulose nanofiber‐based aerogel exhibits excellent thermal‐isolating as well as flame‐retardant properties. The composite aerogel displays flameless pyrolysis as well as increased residue char. A fire‐warning detector is designed to reliably monitor the early fire. Based on the flame‐induced electrical resistance transformation characteristic of GO, it endows the composite aerogel with an ultra‐fast fire‐response time of ~2.6 s and a durable alarm signal. The flame‐retardant and fire‐alarm mechanisms are concluded. Overall, these results suggest that this composite aerogel has an enticing prospect in chemical industries and high‐rise buildings, which may lay the foundation for designing multifunctional TIMs. The modified aerogel broadens its application territory by intrinsic fire‐alarm characteristics, which covers the deficiency of delaying reaction as well as restricted application scenarios in traditional fire detectors. [ABSTRACT FROM AUTHOR]

Thermal insulation materials (TIMs) are widely used to realize energy conservation in buildings, but most of the commonly used organic TIMs are flammable. A novel biomass‐based aerogel is produced by an environmentally friendly vacuum freeze‐drying method, and a facile approach is proposed to improve the flame‐retardant performance of cellulose nanofiber (CNF) aerogels by modifying them with graphene oxide (GO) and montmorillonite (MMT). GO and MMT form a barrier that blocks the contact between the composite aerogel and the external oxygen, achieving the flame‐retardation effect. Notably, based on the high‐temperature thermal reduction characteristic of GO, a fire‐alarm system that can provide an ultrasensitive and reliable fire‐warning signal is designed. A fire alarm of CNF‐MMT‐GO‐50% can be triggered in approximately 1.9 seconds and lasts for more than 137.0 seconds when the aerogels are attacked by fire. This work helps to develop advanced TIMs to solve the shortcomings of traditional organic insulation materials and supplies a newfangled idea for the design of fire‐alarm sensors, showing promising applications in building insulation, firefighting, and chemical industry. [ABSTRACT FROM AUTHOR]

• Nacre-like GO-PTA paper is prepared by evaporation-induced self-assembly method. • Fire sensor-based GO-PTA exhibits ultrasensitive and durable warning response. • Enhancement in fire resistance of GO is attributed to in situ phosphorus doping. A novel nacre-like flame-retardant paper based on graphene oxide (GO), and phytic acid (PTA) is fabricated via evaporation-induced self-assembly. This facile method is time saving and low energy consuming. A facile approach is proposed to improve thermal oxidative stability of GO paper by in situ phosphorus doping during flame exposure. Then fire-alarm system is designed based on the high-temperature thermal reduction characteristic of GO. The GO paper functionalized with PTA (GO-PTA) can provide ultrasensitive, reliable and longtime fire early-warning signal. Fire alarm can be triggered at approximately 0.50 s when GO-PTA samples are attacked by fire. Phosphorus atoms are in situ doped into graphene layers during fire exposure, endowing GO-PTA paper with outstanding thermal oxidative stability, and thus alarm duration time of GO is greatly improved. The work develops advanced fire detection and early-warning sensors that provide reliable and continuous signals, which provide more available time for fire evacuation. [ABSTRACT FROM AUTHOR]

Zirconium phenylphosphonate (ZrPP) nanoplatelets are decorated on the surface of reduced graphene oxide (RGO) based on π–π assembly interactions. The structure, composition, and morphology of ZrPP‐RGO assembly nanohybrid are well characterized. The dispersion of graphene in the nonpolar polypropylene (PP) matrix is improved by this modification. The enhancement mechanisms of dispersion in polymer matrix are clearly demonstrated. Significant improvements in flame retardancy and fire safety of PP are obtained by the incorporation of this assembly nanohybrid. Peak heat release rate and total heat release of PP composite containing 2 wt% ZrPP‐RGO assembly nanohybrid decrease by 35.8% and 23.6%, respectively, compared to those of neat PP. The assembly nanohybrid exhibits higher flame‐retardant effect than the counterparts of RGO and ZrPP. Furthermore, storage modulus of PP is greatly improved by this nanohybrid. This work proposes a novel method to prepare graphene‐based organic–inorganic nanohybrid and will expand the application of graphene. POLYM. COMPOS., 40:E1757–E1765, 2019. © 2018 Society of Plastics Engineers [ABSTRACT FROM AUTHOR]

Artificial nacre-like inorganic-organic hybrid films are fabricated by a facile evaporation-induced self-assembly method using graphene oxide (GO) nanosheets as rigid bricks and a natural polysaccharide of sodium alginate (SA) as soft mortar. To further improve tensile mechanical properties of the GO/SA films, Ca 2 + is utilized as a substitute for the most widely used glutaraldehyde to crosslink the films. Owing to the high chelation affinity for metal ions, the Ca 2 + modified (Ca-GO/SA) films show higher tensile mechanical properties than those of the original samples. Water uptake in the Ca-GO/SA film is greatly decreased and water stability is improved by the introduction of Ca 2 + . The Ca-GO/SA films exhibit water-triggered shape recovery behavior. The films show two-way shape memory effect and possess two original shapes, which can be reversibly transformed by immersion in water and removal of the absorbed moisture. This advanced hybrid film will broaden the applications for biomimetic materials and shows potential for applications in the fields of water-sensitive actuators and sensors. [ABSTRACT FROM AUTHOR]

B, N- and P, N-doped reduced graphene oxide (RGO) are prepared through high temperature annealing method using boric acid and phosphoric acid as the B and P sources, respectively. The synthesized RGO and dual-doped RGO are well characterized by Fourier transform infrared spectroscopy, X-ray diffraction, Raman spectroscopy, X-ray photoelectron spectroscopy and transmission electron microscopy. The heteroatoms are found to be introduced into the graphene structure. The low level of doping (approximately 1.10 at%) exhibits significant improvement in thermal oxidative stability of RGO. In comparison with neat RGO, the temperature at maximum weight loss rate of B-RGO and P-RGO increase by as much as 52 °C and 130 °C, respectively. The mechanism for retarding RGO oxidation by B/P doping is clearly proposed. More stable bond configurations are formed in the B/P-doped RGO. The doped B and P atoms reduce the reactivity of carbon active sites and inhibit the carbon gasification. This work will provide an understanding of thermal oxidative stability of heteroatoms-doped RGO, and offer a strategy for fabricating graphene with elevated temperature applications. [ABSTRACT FROM AUTHOR]

Graphene oxide (GO) is modified by melamine (MA) via the strong π- π interactions, hydrogen bonding, and electrostatic attraction. PP composites are prepared by melt compounding method, and GO/functionalized graphene oxide (FGO) is in situ thermally reduced during the processing. The results of scanning electron microscopy and transmission electron microscopy indicate that FGO nanosheets are homogeneously dispersed in polymer matrix with intercalation and exfoliation microstructure. The FGO/PP nanocomposite exhibits higher thermal stability and flame retardant property than those of the GO counterpart. During the thermal decomposition, the intercalated MA is condensed to graphitic carbon nitride (g-CN) in the confined micro-zone created by GO nanosheets. This in situ formed g-CN provides a protective layer to graphene and enhances its barrier effect. The heat release rate and the escape of volatile degradation products are reduced in the FGO-based nanocomposites. [ABSTRACT FROM AUTHOR]

Abstract: Multifunctional designs of biomimetic layered materials are in great demand for broadening their applications. Artificial hybrid films are fabricated using a simple evaporation-induced assembly method, using nacre as the structural model, two-dimensional reduced graphene oxide (RGO) and magnetic graphene (MG) as inorganic building blocks and poly(vinyl alcohol) (PVA) as glue. The nacre-like films exhibit good mechanical performance, such as high stiffness, strength and toughness. The biomimetic materials possess the shielding properties of electromagnetic pollution. MG based nacre-like films present more significant electromagnetic interference (EMI) shielding performance than RGO film, because of a synergism between dielectric loss of graphene and magnetic loss of magnetic nanoparticles. Average EMI shielding effectiveness (SE) reaches ∼20.3dB over the frequency range of 8.2–12.4GHz (X band) for MG hybrid film only 0.36mm thick. The lightweight, flexible and thin MG artificial hybrid films possess good potential for EMI shielding applications. [Copyright &y& Elsevier]

Highlights: [•] Graphene oxide was modified by maleic anhydride grafted polypropylene with a “grafting-to” method. [•] Functionalized graphene oxide/polypropylene nanocomposites were fabricated by melt blending. [•] The improvements in thermal stability of the nanocomposites were among the most significant ever reported. [•] The mechanism for the decrease in ductility of the nanocomposites was investigated with direct and detailed evidence. [ABSTRACT FROM AUTHOR]

Large size reduced graphene oxide (RGO) tends to restack or form irreversible agglomerates during the conventional drying. In this work, a facile and efficient drying method, involving freezing–thawing–drying approach, is developed to prepare porous RGO. The RGO exhibits a large pore volume (0.414 cm 3 /g) and specific surface area (294.9 m 2 /g). The RGO can be easily ground using mortar and pestle and be dispersed in solvent by ultrasonication. The RGO shows porous nanostructure and poorly-stacked layered structure. Compared with the RGO dried by conventional method, the RGO dried by this modified process possesses similar structural defect density. The ice crystal formed by liquid nitrogen is expected to prevent the restacking of graphene nanosheets and be beneficial to obtain porous structure. [ABSTRACT FROM AUTHOR]

• A novel graphene-based composite paper was synthesized via a facile method. • The electromagnetic shielding performance of RGO/ZnO composite paper was explored. • RGO/ZnO composite paper possesses excellent fire resistance performance. Graphene composites that take advantage of lightweight, easy processing and excellent electrical conductivity are promising candidates as functional electromagnetic shielding materials. Herein, zinc oxide (ZnO) nanoparticles were prepared by hydrothermal method and then were introduced into graphene oxide dispersion. The reduced graphene oxide (RGO)/ZnO composite paper was fabricated by evaporation-assisted self-assembly and then reduced by hydrazine hydrate vapor. The results show that the shielding effect of composite paper increases with the increase in the thickness and ZnO dosage. The total electromagnetic interference (EMI) shielding effectiveness of RGO/ZnO composite paper with a thickness of approximately 1 mm is determined as 46.9 dB in the X band. Furthermore, this composite paper has excellent fire resistance. This lightweight and thin RGO/ZnO paper demonstrates a high-performance advanced composite for cutting-edge EMI shielding application in harsh conditions. [ABSTRACT FROM AUTHOR]

• A novel and sensitive fire early alarm was designed based on GO-BA composite paper. • The sensitivity and stability of this novel alarm was excellent. • Flame alarm mechanism of GO-BA paper was described. Boric acid-modified graphene oxide (GO-BA) paper is prepared by a green and facile water evaporation-induced self-assembly method, and its application as an early fire-alarm sensor is investigated. The nacre structure is constructed by assembling graphene oxide (GO) and boric acid (BA) as brick and mortar, respectively. Compared with pure GO paper, improved thermal-oxidative stability is obtained for GO-BA. GO nanosheets are bonded with BA molecules by forming hydrogen bonds between hydroxyl in BA and the rich oxygen-containing functional groups on GO. Notably, the insulating GO-BA paper can be rapidly thermally reduced to conductive reduced graphene oxide under flame exposure, thus providing an ideal fire-alarm response with a quick flame-detection time of ∼0.8 s. In addition, boron oxide formed under flame attack covers the surface of GO, inhibiting further oxidation of GO paper, and effectively extending the duration time of GO-BA under combustion. These results indicate that the GO-BA paper prepared has a broad prospect in the field of fire early-alarm. [ABSTRACT FROM AUTHOR]

Electrical fire is the most frequently occurred fire accident, and fire sensors with self-cutting and ultrasensitive fire-alarm response capability are urgent to be designed and developed. Herein, conductive reduced graphene oxide paper (RGOP) with hierarchical structure is prepared by a facile evaporation-assisted self-assembly of graphene oxide (GO) dispersion and then reduction by hydrazine hydrate vapor. The oxidative decomposition of RGOP containing sodium chloride (RGOP-NaCl) is promoted by the addition of NaCl. When being exposed to flame, RGOP-NaCl strips are readily ruptured. Based on this distinctive self-cutting performance of RGOP-NaCl under fire attacking, a novel fire detection and alarm device is designed by establishing controlling and operation circuits. Under fire encountering, an ultrafast warning response (approximately 5.3 s) of RGOP-NaCl is triggered. Fire-alarm time of RGOP-NaCl is adjustable by varying the content of NaCl. Furthermore, this RGOP-NaCl has the function of fuse and can cut off the conductive circuit timely under fire attacking. This finding will provide a novel thought for the design of advanced fire-alarm sensor and will also expand the application of graphene paper. Image 1 • Conductive RGOP-NaCl is prepared by evaporation-induced self-assembly method. • This RGOP-NaCl exhibits ultrasensitive fire-warning response. • RGOP-NaCl has the function of fuse and self-cutting performance under fire attack. [ABSTRACT FROM AUTHOR]

• GO-PA paper is prepared by an evaporation-induced self-assembly method. • Fire sensor based GO-PA exhibits ultrasensitive and durable warning response. • Enhancement in fire resistance of GO is attributed to in situ phosphorus doping. Although traditional fire detectors are widely used in many occasions, they still show some limitations, such as slow fire response and poor resistance to severe conditions. Thus, it is urgent to design and exploit early fire-warning device with ultrafast response and flame-retardant ability to provide timely and fast alarm. Herein, graphene oxide paper functionalized with phosphoric acid (GO-PA) is fabricated by a facile and environmentally friendly water evaporation-induced self-assembly approach. Based on the flame-induced electrical resistance transformation characteristic of GO-PA, a fire-warning detector is designed to reliably monitor early fire. Fire alarm can be triggered within 0.5 s when GO-PA samples are attacked by fire. The GO-PA composite paper is more sensitive than GO-based fire sensors reported in the literature. Phosphorus atoms are in situ doped into graphene structure during flame exposure. Combustion reaction of GO is significantly retarded by the incorporated PA, thus fire duration time of GO is greatly improved. This work paves a new way to improve fire detection performance of GO-based sensors. This work provides a guide for the development of advanced fire detection and early-warning sensors to provide reliable and continuous alarm signals. [ABSTRACT FROM AUTHOR]

• Porous reduced graphene oxide paper (RGOP) was facilely constructed. • RGOP shows superior fire resistance. • RGOP exhibits outstanding electromagnetic interference shielding performance. Free-standing bifunctional reduced graphene oxide paper (RGOP) was facilely fabricated by evaporative self-assembly and hydrazine hydrate vapor reduction. The RGOP integrates remarkable fire resistance and outstanding electromagnetic interference (EMI) shielding performance with a total shielding effectiveness value of 41.5 dB at 0.49 mm thickness in the X band. This research provides a facile pathway to fabricate graphene macro-assembly for fire safety and EMI shielding applications. [ABSTRACT FROM AUTHOR]

The eco-friendly and simple layer-by-layer (LbL) self-assembly process is used to create a graphene oxide (GO) and aluminum oxide hydroxide (AlOOH) functional coating on melamine foam (MF) by utilizing the hydrogen bonding interaction. The manufactured composite foam exhibits good hydrophobicity and structural stability in the both strong acidic and alkaline solutions. The AlOOH-GO composite coating's electrical resistance is susceptible to flame and high temperature, allowing for ultra-fast fire detection and efficient fire-warning response. When the composite foam is attacked by flame, it triggers an alarm signal within 2.5 s and a continuous alarm time access of 256 s, demonstrating exceptional early fire-warning capability. The thermal stability of this combustible foam is improved by the optimized AlOOH-GO composite coating. The AlOOH-GO composite coating endows MF with exceptional flame-retardant properties, including self-extinguishing and structural integrity after combustion. This work proposes an efficient method for considerably reducing the fire hazard of flammable materials and expanding the applications in a fire early detection and warning. [Display omitted] • A novel early fire-alarm sensor was designed based on AlOOH-GO nano-coating. • The sensitivity and stability of this novel fire sensor were excellent. • The fire-alarm and flame-retardant mechanisms of AlOOH-GO nano-coating were studied. [ABSTRACT FROM AUTHOR]

• A fire-alarm biomass aerogel was prepared by freeze-drying method. • The composite aerogel displays excellent flame-retardant performance. • This fire-alarm aerogel provides early fire warning detection. Flame-retardant thermal insulation materials (TIMs) with a function of fire warning will play a critical role in the fields of sustainable energy saving and fire safety. Herein, we fabricated a fire-alarm aerogel based on biomass sodium alginate and hydroxyapatite, introduced with graphene oxide. This aerogel exhibits good thermal insulating properties due to its porous network. The composite aerogel displays good flame-retardant performance and can provide early fire warning detection. At room temperature, the aerogel is electrically insulating, but it switches to an electrical state when exposed to flame. The aerogel connected with an alarm light can give ultrafast response time (within 1.5 s) and sustained warning time (over 60 s) under sudden fire attacks. This modified aerogel provides a promising strategy for the functional application of TIMs. [ABSTRACT FROM AUTHOR]