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Wood, renowned for its sustainability, specific strength, and thermal insulation, stands as a highly sought-after sustainable structural material. However, the inherent flammability, decay susceptibility, and inadequate mechanical strength hinder its practical applications in high-rise buildings. Here, we report a groundbreaking solution to fabricate multi-functional fire-retardant wood (M-FRW) through a coupled delignification/impregnation procedure followed by densification treatment. The GO/BA created a hybridized network on the M-FRW surface, while BA molecules penetrated the wood cell. As-created M-FRW exhibits a superior flame retardancy due to the physical barrier and catalytic charring effect of GO/BA, as reflected by an ultrahigh limiting oxygen index value of >75 % and an 85 % reduction in the peak of heat release rate compared to natural wood. Furthermore, the GO/BA layer of M-FRW has a sensitive fire alarm response and ultralong alarm time (∼11280 s). More impressively, M-FRW exhibits an exceptional ability to inhibit decay fungi, mold fungi, and common bacteria due to the superimposed anti-microbial effect of GO and BA. Additionally, M-FRW shows desirable mechanical and thermal insulation properties. This work provides a facile strategy to fabricate a multi-functional advanced wood nanocomposite, making them hold great potential for various engineering applications, such as intelligent buildings. A highly fire-retardant, fire-warning, anti-microbial, and mechanically robust wood nanocomposite based on graphene oxide and boric acid has been developed using a graded-penetration impregnation strategy. The as-prepared multifunctional wood nanocomposite holds great promise for many engineering applications in buildings. [Display omitted] • A M-FRW was prepared by combining delignification, impregnation and densification. • PHRR and PSPR of M-FRW reduced by 85 and 78 % compared to natural wood, respectively. • M-FRW exhibits sensitive fire alarm response and ultralong alarm time (∼11280 s). • M-FRW shows excellent resistance to decay fungi and common bacteria. • The tensile strength of M-FRW is 3.1 times higher than natural wood. [ABSTRACT FROM AUTHOR]

A synergistic flame retardant with a core-shell structure utilizes the 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) derivative as the outer shell and ammonium polyphosphate (APP) as the inner core. Three derivatives of DOPO (DOPO-GY, DOPO-DH and DOPO-GD) are synthesized by reacting DOPO with glyoxal, paraformaldehyde and diethanolamine, and glutaraldehyde, respectively. DOPO-GY@APP, DOPO-DH@APP and DOPO-GD@APP exhibit good radical scavenging activities. The oxidation induction time for EVA/DOPO-GY@APP is exceptionally high at 19.04 min, in contrast to EVA alone, which has an induction time of only 5.51 min. Simultaneously, after aging at 180 °C and 165 °C for 7 days, the retention rates of elongation at break for EVA/DOPO-GY@APP are 34.67 % and 55.50 %, respectively. These findings demonstrate the long-term anti-aging properties of EVA/DOPO-GY@APP without the need for additional antioxidants. Moreover, EVA/DOPO-GY@APP, EVA/DOPO-DH@APP and EVA/DOPO-GD@APP all achieve V-0 rating with 25 % addition of flame retardant. In comparison to pure EVA, their peak heat release rates and maximum smoke density decrease by 52 % and 47 %, 43 % and 54 %, and 51 % and 44 %, respectively. Additionally, compared to EVA/APP, their mechanical properties have been improved. Therefore, these microencapsulated flame retardants with DOPO derivatives as the shell effectively enhance the mechanical properties and fire safety of EVA composites. [Display omitted] • A multifunctional microencapsulated flame retardant is successfully designed. • The DOPO-GY@APP shows good radical scavenging activities. • The retention rate of EB from EVA/DOPO-GY@APP can reach 55.50 % after aging at 165 °C for 7 days. • EVA/DOPO-GY@APP reveal anti-aging properties without adding any antioxidant. • The pHRR and Ds max of EVA/DOPO-GY@APP are reduced by 52 % and 47 %, respectively. [ABSTRACT FROM AUTHOR]

Polyurea (PU) elastomers have become increasingly popular in recent years due to their exceptional blast mitigation, ballistic protection, and wear resistance properties. However, their applications as protective materials are often limited as a result of their high flammability. In this study, aromatic dianhydrides (ArDAs) were employed to capture the thermal decomposing products of PU during combustion and facilitate the generation of highly heat-resistant aromatic polyimides (i.e., end group capturing effect), thus enhancing the material's char-forming ability and improving its flame retardancy. The ArDAs were found to significantly reduce the peak heat release rate (PHRR), total heat release (THR), total smoke release (TSR), and total CO release (TCO) of PU, and meanwhile increased the amount of char residue. At 20 wt% content of 3,3′,4,4′-benzophenonetetracarboxylic dianhydride (BTDA), PHRR, THR, TSR and TCO of PU were reduced by 70.6%, 32.5%, 44.7% and 58.8%, respectively, the char residue was increased by 405%, and the mechanical properties of PU were well maintained (88.5% tensile strength and 91.0% elongation at break of pure PU). These findings demonstrate that ArDAs could serve as a new kind of halogen/phosphorus-free flame retardant for PU elastomers. [Display omitted] • Novel halogen/phosphorus-free flame retardants were designed for PU elastomers. • The flame retardant mechanism is end group capturing by aromatic dianhydrides (ArDAs). • PHRR, THR, TSR and TCO were simultaneously reduced, and char residue was improved. • Both excellent flame retardant property and high mechanical property were achieved. [ABSTRACT FROM AUTHOR]

Impact injuries and fire risks generally coexist simultaneously in extreme environments. In this context, it is of great necessity to design impact resistant materials with both flame retardant performance and thermal stability. Here, a multi-functional flame retardant coating was prepared from the combination of silica sol (Si-sol), phytic acid (PA) and expandable graphite (EG) by graft modification with γ-propyl-trimethoxysilane (KH550). Subsequently, hierarchical composites were fabricated using one-pot foaming and brush coating method, where the carbon fiber cloth and coating served as the surface layer, while rigid polyurethane foams (RPUF) acted as the interlayer. The hierarchical structure endowed the RPUF composites with high compression resistance and impact resistance properties. Furthermore, the flame retardant coating could effectively reduce the values of peak heat release rate and peak smoke production rate of RPUF composites by 77.5% and 81.8%, respectively. Therefore, these RPUF composites can effectively prevent impact damage and achieve excellent flame retardancy, making them promising candidates as safety protective materials. [Display omitted] [ABSTRACT FROM AUTHOR]

A phosphorous-silicon (SiP) precursor was synthesized using p-phthalaldehyde, (3-aminopropyl) triethoxysilane and 9,10-dihydro-9-oxa-10-phosphaphenantrene-10-oxide. The SiP was used to fabricate a phosphorous-silicon hybrid microsphere (SiP-M) via the sol-gel method. The SiP-M was employed to enhance the flame retardancy of poly (butylene adipate-co-terephthalate) (PBAT). The results indicate that PBAT containing 0.1 wt% of SiP-M displays a UL-94 V0 rating and a limiting oxygen index (LOI) value of 26.5 vol%. Meanwhile, PBAT containing 1.0 wt% SiP-M exhibits a UL-94 V0 rating and a LOI value of 29.8 vol%, and some reductions in peak heat release rate, total heat release, and total smoke production. The SiP-M functions in both the gas phase and condense phase in the PBAT blend, and the former is predominant. In addition, a coupling agent KH560 was used to modify the interface adhesion between PBAT and SiP-M. The tensile strength and elongation at the break of PBAT blends are enhanced by an appropriate amount of KH560. This work provides an efficient method for preparing flame-retardant PBAT without deteriorating its mechanical properties. Poly (butylene adipate-co-terephthalate) with 0.1 wt% P/Si hybrid microsphere displays a UL-94 V0 rating. [Display omitted] • A phosphorous-silicon microsphere SiP-M was used in poly (butylene adipate-co-terephthalate) (PBAT). • A small amount of 0.1 wt% SiP-M endows PBAT with a UL-94 V0 rating. • SiP-M works mainly in the gas phase during combustion. • A coupling agent regulates the mechanical properties of PBAT/SiP-M blends. [ABSTRACT FROM AUTHOR]

The incorporation of flame retardants (FRs) is often applied to reduce the fire risk of flexible polyurethane foam (FPUF), however, the addition of FRs usually brings mechanical loss, and the emigration of FRs during service life results in a decrease in flame retardancy. In this work, a hyperbranched FR (HPNP) containing nitrogen and phosphorous was synthesized via transesterification between dimethyl methyl phosphonate (DMMP) and triethanolamine. The distribution of HNPN in FPUF was simulated by the Materials Studio software. The flammability was characterized by the open flame test, horizontal combustion test, limiting oxygen index (LOI) and cone calorimeter test. The FPUF sample containing only 4 wt% HPNP self-extinguished immediately after the removal of the ignitor. For the FPUF containing 8 wt% HPNP sample, the LOI was increased to 26.3% from 17.9%. The total heat release and total smoke production were reduced by 65% and 75%, respectively compared to that of the control FPUF sample. More importantly, the radical trapping action in the gas phase and the charring promotion in the condensed phase were simulated and verified based on the experimental data. Furthermore, the interfacial energy calculation and molecular dynamics simulation suggested that the improved compatibility of FPUF/HPNP resulted in the superior durability of HPNP in FPUF. In addition, the FPUF samples containing HPNP also showed enhanced mechanical properties. It was expected the hyperbranched HPNP would be an ideal additive to produce flame retardant FPUF with excellent comprehensive performance. [Display omitted] • A hyperbranched flame retardant (HPNP) was synthesized by transesterification. • FPUF containing 8 wt%HPNP showed self-extinguish effect with an LOI of 26.3%. • Total smoke release of FPUF was greatly reduced by the presence of 8 wt% HPNP. • The addition of HPNP also enhanced the mechanical properties of FPUF. • The improved compatibility of HPNP and FPUF suppressed the emigration of HPNP. [ABSTRACT FROM AUTHOR]

Interest in advanced multifunctional composite materials has generated extensive discussions on materials endowed with high fire-resistance, mechanical strength, and excellent electromagnetic interference (EMI) shielding. We designed a feasible and low-cost method for preparing mechanically robust thermoplastic polyurethane/triazine-rich polyphosphazene functionalized titanium carbide@copper phytate/carbon fiber fabric (TPU/PZM@CP/CF) nanocomposites with enhanced fire retardancy and EMI shielding performances. The as-prepared TPU/PZM@CP-2.0/CF demonstrated excellent mechanical toughness, with a tensile strength of 57.8 MPa. Additionally, this nanocomposite exhibited superior EMI shielding performances, with an EMI shielding effectiveness of 29.7 dB and a normal shielding effectiveness of 24.8 dB/mm, surpassing that of most other TPU-based nanocomposites. Furthermore, the thermal stability and fire resistance of the TPU/PZM@CP nanocomposites were significantly improved. For instance, the peak of heat release rate and the peak of smoke production rate of the TPU/PZM@CP-2.0 respectively decreased by 41.5% and 21.5%, compared to those of neat TPU. In this work, the simple preparation method and outstanding comprehensive performances of the mechanically strong multifunctional TPU/PZM@CP/CF have tremendous potential for applications in defense, smart electronic device and aerospace. [Display omitted] • High-performance multifunctional hierarchical nanosystem are prepared. • Nanocomposites has high fire safety, mechanical robustness and EMI shielding. • Properties of hierarchical nanocomposite are superior to those previously reported. • Hydrogen bond, charring and continuous network lead to properties improvement. [ABSTRACT FROM AUTHOR]

The intumescence, compactness, and strength of char are the key points to the intumescent flame retardant system. However, the char residues of flame retardant polymers rarely exhibit all three characteristics, especially strength. Herein, a novel Cu2+-doped intumescent flame retardant (Cu–CHP) was prepared without producing any waste. When Cu–CHP was exposed at a high temperature (∼1400 °C), it can rapidly expand and carbonize to form dense char. Surprisingly, the intumescent char residue of Cu–CHP can hold up more than 2000 times its own weight. Benefitting from the excellent intumescent charring capacity of Cu–CHP, the resultant EP/Cu–CHP 18% composite can withstand around 600 s penetrating of butane flame (∼1400 °C) because of strong dense char protection, and only 0.9 wt% Cu2+ content resulted in the limiting oxygen index (LOI) of EP/Cu–CHP 18% increases to 31% and the vertical burning (UL-94) reaches V-0 rating. Additionally, its peak heat release rate, total smoke production, and fire growth rate are significantly reduced by 70%, 53%, and 75%, respectively, compared with neat epoxy resin. Especially, the smoke density of EP/Cu–CHP 18% was dramatically dropped by more than 68%. Because a Cu2+-doped intumescent, compact, and strong char residue was produced during burning. This work provides a new strategy to impart excellent flame retardancy and smoke suppression to highly flammable polymers by building metal-doped strong intumescent char residues. [Display omitted] • Cu2+-doped flame retardant was prepared without producing any wastes. • Cu2+-doped intumescent, compact, and strong char residue was produced. • Excellent flame retardancy and smoke suppression were imparted to epoxy resin. • The intumescent flame retardant mechanism was proposed. [ABSTRACT FROM AUTHOR]

To explore new flame retardant molecules with higher flame retardancy and toughening effect, a series of non-halogen block copolymer flame retardants PAPO-MP were designed and synthesized. Importantly, compared with the control sample 24(7PAPP/3MPP)/76PP in which the intumescent flame retardant was physically blended, the mechanical properties of 24(7PAPO-3MP)/76PP with the block copolymer was greatly increased. Its impact strength and elongation at break of 24(7PAPO-3MP)/76PP were 55.1 kJ/m2 and 140.6%, increased by 166% and 965% in contrast to those of 24(7PAPP/3MPP)/76PP, respectively. Because the block copolymerized structure led to the low crystalline degree, 7PAPO-3MP can change its particle shape from lamellar to water droplet morphology during thermal processing, which contributed to better compatibility and stronger interaction with PP matrix under the action of maleic anhydride grafted polypropylene, thereby dramatically enhancing the mechanical properties of PP composites. When the addition amounts of 7PAPO-3MP were 20 wt% and 24 wt% in polypropylene (PP) composite, the two flame retardant PP composites all passed UL94 V-0 rating and had the LOI values of 28.1% and 30.2%, respectively. Their peak of heat release rate values was all decreased by over 81% compared with that of neat PP. Moreover, their total heat release and average effective heat of combustion were also decreased and brought higher residue yields. Moreover, the more release of P-containing components in block copolymer also imposed more effective gas-phase quenching effect and flame inhibition effect during combustion. The research on the block copolymer in PP composites revealed a superior way to construct high-performance non-halogen polyolefin materials. [Display omitted] • A non-halogen block copolymer flame retardant PAPO-MP were synthesized. • PAPO-MP markedly raised mechanical properties of PP compared with blending one. • The water droplet morphology of PAPO-MP led to better mechanical properties. • PAPO-MP also brought better gas-phase flame retardant effect to PP. [ABSTRACT FROM AUTHOR]

Currently, the promotion of flame retardancy is facing apparent decrease of mechanical properties for polyolefin, leading to an unresolved contradiction in this field. In this work, novel hyperbranched polyamide-amine based phosphorous-containing flame retardant PPAM-AT was designed to fabricate flame-retarded polypropylene (PP). Interestedly, when the flame retardancy of PP was greatly improved after incorporation of PPAM-AT, mechanical properties of flame-retarded PP were barely damaged compared with corresponding properties of neat PP. At 15% PPAM-AT, the limiting oxygen index (LOI) of PP/PPAM-AT 15 reached 30% and the highest V-0 grade was achieved in the burning test; the peak of heat release rate (PHRR) and fire growth rate of PP/PPAM-AT 15 were decreased by 83.8% and 60.7% in comparison with corresponding values of neat PP. Meanwhile, tensile strength and elongation at break for PP/PPAM-AT 15 maintained at 46.9 MPa and 551.3%, respectively, keeping at a comparative level with that of PP. Analysis on flame-retardant mechanism confirmed that typical intumescent flame retardation played a vital role for the excellent fire safety of PP/PPAM-AT. The reason for excellent mechanical properties of flame-retarded PP/PPAM-AT is ascribed to the multiple factors such as the change in the crystallization of PP, excellent energy-dissipating ability of PPAM-AT, and so on. This work demonstrated that hyperbranched polyamide-amine based phosphorous-containing flame retardant with unique chemical structure may achieve simultaneous flame retardancy and high performance of polypropylene, which opens a new pathway to solve the contradiction between flame retardancy and high performance of polyolefin. [ABSTRACT FROM AUTHOR]

Firefighting protective clothing is an essential equipment for firefighters that can provide protection from all kinds of thermal hazards and prevent burn injuries. However, it is still a challenge to develop lightweight firefighting clothing without compromising their excellent fire-resistant and thermal-protective performance. In this study, we report a novel polyimide aerogel fiber-based double-layer smart textile comprising of flame-retardant outer layer (ambient-side) with excellent fire resistance and phase-changeable inner layer (next to skin side) with thermal-regulating function, achieving comprehensive flame-retardant and thermal-protective function. The polyimide-hydroxyapatite-reduced graphene oxide (PI-HAP-rGO) aerogel fabric (outer layer) acquires 54.7% and 70.0% reduction of peak heat release rate compared with that of pure PI aerogel fabric and commercial aramid fabric, respectively, exhibiting excellent fire resistance. The phase-changeable polyimide-hydroxyapatite/eicosane (PI-HAP/C20) fabric (inner layer) with high melting enthalpy of 193.2 J g−1 can delay the temperature rise by thermal buffering effects during the phase change process, endowing cool somatosensory temperature for firefighters. Consequently, the double-layer smart textile can extend the time (280.0 s) to pain threshold of human skin, much longer than that of the commercial aramid fabric (101.0 s) and glass fiber fabric (56.5 s), which exhibits huge potential for next-generation firefighting clothing. A novel polyimide aerogel fiber-based double-layer smart textile comprising of flame-retardant outer layer and phase-changeable inner layer exhibited outstanding flame-retardant and thermal-protective performance, demonstrating great potential for next-generation firefighting clothing. [Display omitted] • The smart textile comprising of PI-HAP-rGO aerogel fabric as the outer layer and PI-HAP/C20 fabric as the inner layer was fabricated. • PI-HAP-rGO aerogel fabric exhibits efficient fire resistance with the limited oxygen index value (LOI) up to 47.5%. • There exists 70.0% reduction of PHRR for PI-HAP-rGO aerogel fabric compared with that of commercial aramid fabric. • PI-HAP/C20 fabric has excellent thermal management with high melting enthalpy (193.2 J g−1). • The smart textile could delay around 280.0 s to reach pain threshold in the high temperature environment. [ABSTRACT FROM AUTHOR]

Lightweight, mechanically flexible and flame retardant polydimethylsiloxane (PDMS) foam materials modified with low content of nano-fillers are highly needed for versatile applications. Instead of the direct mechanical mixing technique that induced the embedment of nanofillers inside the matrix, herein, a facile, rapid and green restricted assembly strategy was established to prepare PDMS foam composites coated with an extremely low content of restricted graphene oxide (GO) sheets. A GO/water mixture in silicone oil emulsion was prepared to produce the restricted assembly of GO layers precisely and solely on the foam surface with no GO sheets inside the skeleton. Based on such restricted assembly induced by the amphiphilic surfactant molecules, the presence of only ∼0.04 wt% GO greatly improved the flame resistance (e.g., 40.6% reduction in heat release rate and 27.1% of limit oxygen index) of PDMS foams without affecting the low density (∼0.23 g/cm3) and mechanical flexibility (unchanged stress at strain 70% after 100 cycles under 200 °C). Observations and analysis of the burnt zones demonstrated that the restricted ultralow content GO sheets formed a compact protective layer facilitated by the pyrolysis of the PDMS molecules, thus protecting the inside of the PDMS material from the heat and oxygen attacks. These results confirmed that the restricted self-assembly of 2D nano-fillers approach is effective for the fabrication of flame-retardant PDMS foams and retention of other important properties. [ABSTRACT FROM AUTHOR]

High efficient flame retardant surface treatment through a simple and universal strategy has attracted considerable interest. In this work, polyphosphonamide (PPA) was synthesized via an eco-friendly amine ester exchange reaction, and then the polydopamine-polyphosphonamide (PDA-PPA) coating was constructed by a mussel-inspired phenol-amine co-deposition on the surface of various substrates (cotton, polyethylene terephthalate, poly (lactic acid), polyamide, polypropylene fabrics, and flexible polyurethane foam). It was demonstrated that the PDA-PPA coating significantly improved the flame retardancy of the six substrates. For example, in the case of PDA-PPA coated cotton fabric sample, the limiting oxygen index was increased to 28.3%, the peak of heat release rate and total heat release was decreased by 70.6% and 48.2%, respectively. Especially in the vertical and horizontal burning tests, all PDA-PPA coated samples were self-extinguished and free of molten droplets. It was suggested that the PDA-PPA coating released P-containing radicals to capture active small free radicals and released non-combustible gases to dilute combustible volatiles in the gas phase. In addition, the coating showed excellent intumescent charring ability and promoted the char formation of all substates except polypropylene. Surprisingly, the coating also improved the breaking strength of the PDA-PPA coated fabric and the compressive stress of the PDA-PPA coated foam samples. It was believed that this work provides a scalable and promising strategy for preparing fire safety polymeric materials with a large specific surface area. [Display omitted] • Polyphosphonamide (PPA) was synthesized by an eco-friendly approach. • Polydopamine (PDA) -PPA coating was constructed on the surface of six substrates. • All PDA-PPA coated samples were self-extinguished and free of molten droplets. • The PDA-PPA coating exerted a comprehensive inhibition on combustion. • A facile, universal strategy for flame retardant surface treatment was proposed. [ABSTRACT FROM AUTHOR]

Devoting to coping with safety risk spreading with polymers, this work achieves dramatic synergistic improvements in composite toughness, photothermal healing, and fire safety through a novel targeted modification strategy for black phosphorus (BP). In detail, we herein use the emerging 2D BP as a template for in-situ growth by covalent triazine framework (HBP-CTF). Incorporating gradient increased HBP-CTF (1, 2, 4 wt%) into polystyrene (PS), the elongation at break increased by 61.59%, 74.60% and 62.82% for composites, respectively. This is attributed to the synergistic effects of two components of HBP-CTF as stress conduction unit and interface and dispersion improver, respectively. Furthermore, PS/HBP-CTF composites achieve photothermal healing over 96% in strength and elongation at break induced by outstanding photothermal properties (linearly quantifiable, R2 > 0.997). Noted, PS/HBP-CTF 2.0 and PS/HBP-CTF 4.0 achieve record reductions of 61.77% and 69.85% in peak heat release rate, accompanied by dramatically reduced total heat release. Taking the pyrolysis of HBP-CTF as an index, this work proposes the idea of using P 4 as the key product to monitor and distribute gas phase effects for BP-based flame retardants. The hybridization of CTF to HBP promotes the slow and continuous release of P 4 in the gas phase, revealing the structure and composition of char that cross-linking P and N. This work provides strategies for synergistically overcoming composite brittleness, crack failure, and high flammability, paving the way for practical applications. [ABSTRACT FROM AUTHOR]

Flexible polyurethane foam (FPUF) is one of the most promising cushioning materials, but its high flammability limits its further application. Here, a flame retardant coating was constructed on the foam surface by dipping based on tea polyphenols (TP), phytic acid (PA) and Fe 2 (SO 4) 3 · x H 2 O. The results reveal that the flame retardant coating can dramatically improve the fire safety of FPUF. FPUF/TP-Fe-3PA can pass the UL-94 V-0 rating and the limiting oxygen index reaches 26.2%. Meanwhile, the peak heat release rate and total smoke production of FPUF/TP-Fe-3PA are reduced by 67.7% and 66.7%, compared with those of pure FPUF. Moreover, the flame retardant coating can keep more isocyanates in the condensed phase during the thermal degradation process. The flame-retardant and smoke suppression mechanisms are proposed. What is more, the existence of the flame retardant coating has little effect on the resilience of FPUF. This work provides a simple, green and renewable flame retardant FPUF. [ABSTRACT FROM AUTHOR]

To tailor the enhancement strategies for polymers according to structure, inspired by the concept of "Cannikin's Law", this work proposes and exemplifies a novel strategy for reinforcing the carbonate linkages to simultaneously improve the thermal and fire safety of polycarbonate (PC). Herein, we introduce MIL-53(Al) to functionalize black phosphorus (BP@MIL-53) via a simple method of hydrothermal. As expected, the incorporation of BP@MIL-53 (1.0 wt%) in PC, resulted in an increase in T 1% of 32 °C and 41 °C under nitrogen and air respectively, along with the reduction of 49.4% and 19.3% for peak heat release rate and total heat release. Moreover, PC/BP@MIL-53-1.0 passed the V-0 rating of UL-94 with a high limiting oxygen index (LOI) value of 30.5%, which achieved the dual purpose of simultaneously enhancing the thermal stability and flame retardancy of PC. In addition, the addition of flame retardants had no effect on the tensile strength of the PC. These results demonstrate the high flame retardant efficiency of BP@MIL-53 at ultra-low addition levels. Moreover, these results also illustrate the forward-looking nature of the strategy of tailoring flame retardants to the properties of the substrate. This work combines the advantages of black phosphorus (BP) and Mental organic frameworks (MOFs) materials. The carbonate linkages reinforcement approach provides a viable, new, and scalable idea for polyester compounds' thermal and fire safety properties. [Display omitted] • Novel flame retardants designed to suit the structure of polycarbonate. • Significantly improved thermal stability of polycarbonate. • Highly efficient flame retardant with ultra-low addition levels. • Ester-based reinforcement and char formation strategies inspired by the "Cannikin's Law". [ABSTRACT FROM AUTHOR]

A large amount of cellulose is produced by photosynthesis every year, and cellulose products are widely used in daily life. However, flammability and easy to breed bacteria of cellulose has hidden risk of fire and public health during using, and the materials that can endow cellulose with flame retardancy and antibacterial properties is still lacking. Herein, novel hybrid nanoparticle (SiDP) based on inorganic nano SiO 2 , Schiff base and quaternary ammonium salt was developed to synchronize these two properties. Wherein the thermal stability of nano SiO 2 and the cross-linking structure of Schiff base played as synergistic flame retardant for the nanoparticle while quaternary ammonium salt of N, N′-dimethyl-N-(3-(trimethoxy silyl) propyl) octadecan-1-aminium chloride (DMOAC) was introduced to provide antibacterial property. The results demonstrated that the modified cotton fabrics were significantly out-performing of flame retardancy and antibacterial properties. Wherein LOI increased to 27.6%, the peak of heat release rate (pHRR) reduced by 34.2%, and capability of self-extinguishing was achieved. The antibacterial of SiDP and modified cotton fabrics were substantiated up to 99.9% against the Staphylococcus aureus and Escherichia coli. More excitingly, low toxicity of SiDP was confirmed via MTS assay by L929 fibroblast cells. The anti-infection in-vivo model was constructed and confirmed SiDP had a positive prevention of infection based on the wound healing rate of 91.1% after 14 days' treatment. The flame retardancy, antibacterial and biocompatibility of SiDP indicated it was an ideal candidate of nanomaterials in cellulose modification. [Display omitted] [ABSTRACT FROM AUTHOR]

Inorganic-organic nanocomposites present excellent comprehensive performance due to the combination of the advantages of inorganic, organic, and nanotechnology. However, the preparation methods are usually complex and inefficient, especially not universal. Here, a simple and universal strategy was designed for preparing silica-based nanocomposite flame retardants. Mesoporous silica (m-SiO 2) was used to load ethylenediamine tetra(methylene phosphonic acid) (EDTMPA). Above the melting point of EDTMPA, molten EDTMPA enters into the mesoporous channels of m-SiO 2 by means of capillary force. After cooling, EDTMPA is fixed in the mesoporous cavity to form a flame retardant nanostructure containing silicon, phosphorus, and nitrogen (SiP). The whole process of mesoporous silica-loaded organic flame retardant is simple and green. Adding 3 phr SiP2 into epoxy (EP) resin can reduce the peak heat release rate, total smoke production, and peak CO production by 44.3%, 30.4%, and 45.5%, respectively. Besides, it shows good mechanical properties compared with the EP composites with physically blended m-SiO 2 and EDTMPA. These excellent performances are attributed to the combined effect of EDTMPA and m-SiO 2 as well as the nanoscale effect. This strategy provides a simple, efficient, and general method to prepare nanocomposites by loading molten organic compounds into m-SiO 2. [Display omitted] • A new universal strategy for preparing silica-based nanocomposite is developed. • Molten organic flame retardant was loaded into the channels of mesoporous silica. • A novel flame retardant containing silica, phosphorus, and nitrogen was obtained. • The flame retardant has better comprehensive properties than comparative samples. • The process of mesoporous silica-loaded organic flame retardant is simple and green. [ABSTRACT FROM AUTHOR]

As a biodegradable polymeric material, the polylactic acid (PLA) has broad applications resulting from its various advantages and unique characteristics. Nevertheless, the application of PLA in various fields is greatly limited by its high flammability. Our recent effort focuses on the manipulation of benzyldimethylhexadecylammonium chloride (HDBAC) modified titanium carbide (Ti 3 C 2 T x) ultra-thin nanosheets which are then used to improve the fire safety of PLA composites filled with silicon microencapsulated ammonium polyphosphate (SiAPP). The flame retardant evaluation showed that when 2.0 wt% HDBAC modified Ti 3 C 2 T x (HDBAC-Ti 3 C 2 T x) and 13.0 wt% SiAPP were added, the LOI value was increased to 33.3%, and the UL-94 V-0 level was obtained, besides the peak heat release rate, total heat release, peak smoke production rate and total smoke release decreased by 49.8%, 31.9%, 60.3% and 52.7%, respectively. The barrier and catalytic effects of the modified Ti 3 C 2 T x nanosheets together with the subsequently formed TiO 2 and phosphorus-containing species forming intact expanded carbon layers and interrupting the combustion route are responsible for remarkably improving flame retardancy and suppressing toxic gases of PLA. This work provides a new approach for greatly reducing the fire hazard of PLA. [Display omitted] [ABSTRACT FROM AUTHOR]

The introduction of flame retardants often decreases the ultraviolet (UV) resistance ability of the photo stabilizer. In this work, the antagonistic effect between APP and a light stabilizer HLAS770 was investigated, and the microencapsulated APP (Si-APP) was prepared by coating ammonium polyphosphate (APP) with polysiloxane. Si-APP was introduced into polypropylene (PP) in association with a light stabilizer bis (2,2,6,6-tetramethyl-4-piperidyl) sebacate (HALS770) to synchronously improve both the photo-aging resistance and flame retardancy. The characterization of surface topography, carbonyl index, and mechanical properties demonstrated that the antagonistic effect between APP and HALS770 was eliminated by the presence of polysiloxane. The limiting oxygen index and cone calorimeter test results revealed that the heat and smoke release of aged PP composites containing Si-APP and HALS770 was decreased by 28% and 35% respectively, compared with that of the aged control PP sample, which is crucial to the practical application of PP. It was proved that polysiloxane and HALS770 synergistically improved the photo-aging resistance and flame retardancy of PP. It is suggested that this work provides a new strategy for fabricating long-life flame retardant polypropylene composites. • Si-APP was prepared by microencapsulating APP with a polysiloxane. • Si-APP eliminated the antagonistic effect between APP and HLAS770. • Si-APP showed synergy effect with HLAS770 on delaying photoaging of PP. • HALS770 and Si-APP synergistically improved the flame retardancy of PP. [ABSTRACT FROM AUTHOR]

As known, the poor toughness and low fire safety of bismaleimide resin (BMI) has become a problem which restricts its further application in advanced high-performance field. Therefore, a novel allyl-functionalized linear polyphosphazene (PMAP) was designed and synthesized. With inclusion of 3wt% PMAP, the peak heat release rate (PHRR) and total smoke production (TSP) of BMI/PMAP-3 are reduced by 51.3% and 17.8%, respectively. And the residual char of BMI/PMAP increases significantly as well. Furthermore, the flame-retardant mechanism of BMI/PMAP is proposed. In condensed phase, PMAP can participate in the formation of residual char of BMI/PMAP and the char layer is with an excellent physical barrier effect by the existence of phosphorus oxygen and phosphorus nitrogen cross-linking substances. In gas phase, phosphorous oxygen free radical is also generated from PMAP, which can capture gas-phase chain free radicals and inhibit gas-phase combustion. Moreover, the impact strength of BMI/PMAP-3 increases by 85.3%, which indicates that the toughness of BMI/PMAP is effectively enhanced. The toughening mechanism of PMAP on BMI can be assigned to elastomer toughening. Therefore, with modification of PMAP, BMI/PMAP is indeed of better comprehensive performance, which is in line with expectation and provides inspiration for the simultaneous flame-retardant and toughening modification of BMI. [Display omitted] • Innovation: bifunctional allyl functionalized linear polyphosphazene was firstly synthesized. • High-efficiency: the PHRR and impact strength of BMI/PMAP-3 is reduced by 51.3% and increased by 85.3%. • Mechanism: the flame retardant and toughening mechanism is proposed. [ABSTRACT FROM AUTHOR]

Flexible wearable heaters have received increasing attention in energy-saving, diverse personal thermal requirements, and healthcare management. Herein, considering the fire safety application of wearable heaters, the biodegradable alginate fibers and flame retardant (FR) viscose fibers are attempted to mix and weft-knit into the fabric, which interestingly exhibits synergetic flame retardancy with low afterflame time, afterglow time, and peak heat release rate. Further, assisted by the highly conductive Ti 3 C 2 T x (MXene) nanosheets on the surface of the fabric and the periodic nested loops of the knitted fabric, the integrated fabrics possess excellent electrical performance (2Ω sq−1) with the MXene content of 9.13 wt%, electromagnetic interference (EMI) shielding efficiency of 55 dB in the X band, preferable Joule heating performance under safe low voltage (123 °C at 3.5 V) and sunlight/far-infrared heating performance. The superior flame retardancy and multifunctional properties arose from the high-temperature induced well-constructed char layer, unique functionality of interconnected MXene network and multiple scattering of light or wave. Combined with the superior flame retardancy and multifunctional properties, the weft-knitted alginate/FR viscose fabrics with MXene coating become the ideal candidate materials in the fields of wearable heaters with high safety. [Display omitted] • The weft-knitted alginate/viscose fabrics exhibit synergistic flame retardancy. • The multifunction is achieved by cooperation of MXene and nested loops structure. • The modified fabrics show superior EMI shielding and Joule heating performances. • The fabrics possess photothermal performance under sun/far infrared irradiation. • The fabrics are the ideal candidates for the wearable heater with high safety. [ABSTRACT FROM AUTHOR]

An innovative method of improving PVDF foaming behavior and foam performance by blending with polymethyl methacrylate (PMMA) was devised, and lightweight, strong, flame-retardant foams with wider foaming window and excellent thermal insulation performance were successfully achieved. PMMA not only improves CO 2 uptake and melt viscoelasticity, but also decreases PVDF crystallinity and increases melting range of PVDF crystals. Compared to PVDF foams, expansion ratio of the blend foams increased from 21.9 to 31.2, and effective foaming window was expanded from 3.6 °C to 17.4 °C. Thanks to the blend foams' high expansion and PMMA's strong infrared absorption ability and high rigidity, thermal conductivity and compression modulus of the foams are 33.85 mW m−1 K−1 and 3.51 MPa, respectively. Moreover, the blend foams also show a lower heat release rate and favorable flame retardancy. [Display omitted] • The foaming behavior of PVDF could be significantly improved by blending with PMMA. • The foams have excellent thermal insulation property and favorable flame retardancy. • Introducing PMMA decreases crystal size of PVDF and broadens melting range of PVDF. • CO 2 uptake and melt viscoelasticity of PVDF were facilitated by introducing PMMA. [ABSTRACT FROM AUTHOR]

The aggregation and plasticizing of most 9,10-dihydro-9-oxa-10-phosphaphenanthrene −10-oxide (DOPO) derived additives often result in deteriorating the glass transition temperature and mechanical properties of epoxy resins (EP). To address this issue, an imide-DOPO derivative (BMP) with bulky aromatic structure was successfully synthesized. Benefitting from the space hindering and intermolecular interaction (π-π stacking) of BMP, it does not lead to the loss of glass transition temperature, and only a minor damage of tensile and impact strengths is caused. Additionally, with only 0.78 wt% loading of phosphorus (10 wt% BMP), the EP/BMP 10% achieves UL-94 V-0 and high LOI value of 35%. Simultaneously, both the heat release rate and total smoke production are markedly reduced. More excitingly, BMP exhibits aggregation-induced emission enhancement of fluorescence in the N, N -dimethylformamide/water mixed solution as well as epoxy resin. This work provides a new insight in simultaneously imparting flame retardancy and fluorescence to epoxy resins without losing glass transition temperature. [Display omitted] • Imide-DOPO derivative exhibits aggregation-induced emission enhancement. • Imide-DOPO derivative endows epoxy resin with excellent flame retardancy. • No loss of T g while the improvement of flame retardancy. • Fluorescence is imparted to the flame retardant epoxy resin. [ABSTRACT FROM AUTHOR]

Nowadays, the underlying mechanism for the flame-retardant property derived from the metal-catalyzed pyrolysis of polyphosphazene composites is unclear, thus limiting the efficient utilization and further development of this high-performance catalytic-type flame retardants. Herein, polyphosphazenes terminated with amino (denoted as PNF) and hydroxyl (denoted as PZF) groups are coated on the surface halloysite nanotubes (HNT), thus affording HNT@PNF and HNT@PZF core-shell structures, respectively. Cu nanoparticles (2.6 ± 0.8 nm) are anchored on the surface of these two core-shell structures to generate flame retardants named as HNT@PZF-Cu and HNT@PNF–Cu. Cu nanoparticles show high catalytic thermal rearrangement of polyphosphazene for HNT@PZF-Cu instead of HNT@PNF–Cu, which is attributed to the interaction between Cu and HNT@PZF and a large specific surface area of HNT@PZF (93.5 m2/g). Compared with HNT@PNF–Cu, HNT@PZF-Cu exhibits better smoke suppression and flame retardancy for epoxy resin (EP). With 3 wt% loading of HNT@PZF-Cu, the peak heat release rate, smoke production rate, and carbon monoxide production of the EP nanocomposite are reduced by 52.2%, 40.3% and 64.2%, respectively. This is because polyaromatic compounds generated during the pyrolysis of HNT@PZF-Cu promote the rapid carbonization of EP nanocomposites, resulting in the formation of structural stable char residue. Meanwhile, Cu nanoparticles can effectively reduce the release of toxic fumes and the volatilization of volatile organic compounds (VOCs) during the catalytic combustion process. Density functional theory (DFT) calculation reveals that Cu nanoparticles catalyze the purification of toxic gases such as CO and NO. [Display omitted] • Two novel catalytic-type flame retardants (HNT@PZF-Cu and HNT@PNF–Cu) were incorporated to EP to decrease its fire hazards. • Cu nanoparticles loaded on HNT@PZF-Cu instead of HNT@PNF–Cu show high catalytic thermal rearrangement of polyphosphazne. • HNT@PZF-Cu promotes the rapid carbonization of EP nanocomposites and the formation of stable char. • Cu nanoparticles loaded on the HNT-based carriers catalyze the carbonization and purify the toxic gases. • Density functional theory (DFT) calculation reveals that Cu nanoparticles catalyze the conversion of CO and NO. [ABSTRACT FROM AUTHOR]

Mitigating the fire hazards of epoxy resin (EP) and simultaneously improving mechanical properties have always been a goal pursued by polymeric scientists. Herein, we prepared a lithium-containing hepta-isobutyl-POSS (ibu-T 7 -Li-POSS). The chemical structure of ibu-T 7 -Li-POSS was well characterized. Just via tuning the ethanol solution concentration, we can obtain zero-dimensional (0D) spherical nanoparticles, two-dimensional (2D) ultrathin mono-layer nanoflakes, three-dimensional (3D) multiple-layered lamellae and hexagonal petal-shaped micron-size crystal based on ibu-T 7 -Li-POSS. Regular macroscopic octahedron single crystal of ibu-T 7 -Li-POSS was analisized by single crystal X-ray diffraction. The prepared ibu-T 7 -Li-POSS was incorporated into EP to improve the mechanical properties and enhance the fire safety. When the ibu-T 7 -Li-POSS content was 1 wt%, the flexural strength of EP-1 was enhanced from 81.8 MPa of EP to 110 MPa. The incorporation of ibu-T 7 -Li-POSS can apparently decrease the dielectric constant and loss of EP nanocomposites. Moreover, when 5 wt% of ibu-T 7 -Li-POSS was incorporated into EP, the reduction of peak of heat release rate (p-HRR), peak of smoke production rate (p-SPR) and peak of CO production rate (p-COP) reached to 34.1%, 38.6% and 40.6%, respectively. Therefore, our findings provide a considerable promotion for the facile preparation of low-dimensional environment-friendly nano-/micron-flame retardants based on metal-containing polyhedral oligomeric silsesquioxane (M-POSS) compounds. [Display omitted] • A novel metal-POSS (ibu-T 7 -Li-POSS) is firstly synthesized via one-pot method. • Controllable dimensional ibu-T 7 -Li-POSS nano-/micron-crystals are fabricated. • Thermal stability and mechanical properties of EP nanocomposites are improved by introducing ibu-T 7 -Li-POSS. • Ibu-T 7 -Li-POSS apparently reduces fire hazards of the formed EP nanocomposites. • The mechanism of catalytic charring of lithium for EP is illustrated in detail. [ABSTRACT FROM AUTHOR]

A green and facile strategy for preparing high-efficiency flame retardants is highly desirable given today's increasingly environmentally friendly requirements. In this study, novel bioderived cross-linked polyphosphazene microspheres (PHDTs) were synthesized through polycondensation with tannic acid and 4,4′-dihydroxybiphenyl as co-monomers and decorated by layered double hydroxide (PHDT@FeCo-LDH) to improve the flame retardancy of epoxy resin (EP). Comparison with pure EP revealed that the EP containing 4.0 wt% PHDT@FeCo-LDH exhibited the highest LOI of 29.7 and a UL-94 V-0 rating. Furthermore, the peak heat release rate, total heat release, and total smoke release of the modified EP were significantly reduced and were superior to most of its previously reported counterparts. The PHDTs could be regarded as an all-in-one bioderived intumescent flame retardant for catalyzing the formation of the highly graphitized char layer of a phosphorus-containing cross-linking network in the EP matrix. The transformation of the LDH shell into refractory oxides on the surface of the matrix during combustion further strengthen the structure and thermal stability of the char layer, which effectively inhibited the release of toxic and flammable gases. The flame retardant performance of the modified microspheres was mainly attributed to catalytic charring, free-radical scavenging, and physical barrier effects. Notably, the mechanical properties of the EP composites were improved to meet the requirements of industrial application. This work provides a new methodology for the preparation of high-performance EP composites. [Display omitted] [ABSTRACT FROM AUTHOR]

High fire hazard of releasing considerable toxicants and heat is regarded as a notorious issue for hindering the further application of epoxy resin (EP). Hence, a hierarchical structure (MLBCN) based on LDH anchored boron-doped g-C 3 N 4 assembled with MnO 2 nanosheets is rationally constructed as flame retardant additive for EP. Concretely, the incorporation of 1.0 wt% MLBCN leads to the decreases of 31.9% and 25.3% in peak heat release rate and total heat release, separately, reflecting the impeded heat release. Meanwhile, the peak smoke production rate and total smoke release are reduced by 37.1% and 33.4%, respectively, corroborating the hindered fire toxicity. The clear evidence for inhibited emissions of toxic CO and NO gases can be acquired from TG-IR spectra. These results collectively confirm the efficacy of MLBCN in reducing the toxicants generation and fire hazard of EP, deriving from its physical barrier, chemical catalyzing and charring promotion actions. Besides, the tensile and flexural strength are improved by 43.9% and 10.6%, by adding 1.0 wt% MLBCN, demonstrating the promoted mechanical performance. Overall, using MLBCN achieves the simultaneous enhancements in fire safety and mechanical capability of polymer. This work may provide valuable inspirations for constructing multicomponent hierarchical structure, optimizing their prospects in polymer-matrix composite and other areas. [Display omitted] • LDH anchored boron-doped g-C 3 N 4 assembled with MnO 2 nanosheets (MLBCN) is designed. • Marked impedances on heat release and toxicants emission are achieved by using MLBCN. • Flame retardancy comparison with reported works affirms the superiority of MLBCN. • Obviously promoted mechanical property is also acquired. [ABSTRACT FROM AUTHOR]

Epoxy resins (EPs) are a kind of widely used engineering materials, because of their excellent mechanical, chemical and physical properties, but a severe problem they faced is their poor flame retardancy. Single molecule flame retardants have met the bottleneck after the massive researches of the past decade, so, with the development of the polymer technology, hyperbranched flame retardants have been researched and applied, owing to their better and more efficient flame retardancy. Herein, a facile thermal treating procedure was applied to the cured EP thermosets which contained a crosslinkable additive flame retardant to in-situ form a hyperbranched flame retardant. The single molecule flame retardants with N/P elements and crosslinkable nitrile groups were synthesized through an easy method, and physically mixed with EP matrix. After the curing reaction of EP matrix, the thermosets were further treated with a thermal treating procedure, while transferring the single molecule flame retardant into hyperbranched flame retardant, the semi-interpenetrating network was formed at the same time. The flame-retardant properties have been measured by limiting oxygen index (LOI) tests, UL-94 vertical burning tests and cone calorimeter tests, the results showed the flame retardants were extremely efficient and greatly elevated the flame retardancy of EPs, since the 0.5 wt% content could make modified EP samples pass the UL-94 V-0 rate, and with 20 wt% content the LOI value reached 49.5 % and the peak heat release rate reduced for 71.6 % compared with pure EPs. [ABSTRACT FROM AUTHOR]

Acrylonitrile-butadiene-styrene (ABS) resin is a commonly used engineering thermoplastic. Nevertheless, the fire toxicity hazards (HCN, NO x , NH 3 and CO) generated from the combustion of ABS remains a major concern, especially in building fire scenarios. To address this issue, boron dipyrromethene (BODIPY) modified MXene (Ti 3 C 2 T x) nanosheets were prepared and utilized as a flame retardant for ABS. The loading of 0.5 wt% BODIPY-MXene resulted in the uniform dispersion in ABS. Accordingly, the tensile strength, Young's modulus and elongation at break of ABS/BODIPY-MXene0.5 were improved by 27.8%, 18.6% and 17.9% respectively compared to neat ABS, suggesting the enhanced mechanical properties. The limiting oxygen index (LOI) value was increased from 19.5% for neat ABS to 21.5% and 23.5% for ABS/BODIPY-MXene0.5 and ABS/BODIPY-MXene2.0 benefitted from the rapid carbonization. The cone calorimeter coupled with FTIR analysis showed that the reductions in peak heat release rate (−24.5%), peak smoke production rate (−18.4%), peak concentration of HCN (−33.5%), NO (−22.0%), N 2 O (−46.6%), NH 3 (−76.0%) and CO (−28.8%) were achieved by incorporating 0.5 wt% BODIPY-MXene to ABS in comparison with pure ABS. The improved fire safety properties were primarily attributed to the excellent barrier, free radical capture, and catalytic carbonization effect of BODIPY-MXene nanosheets within ABS matrix. [Display omitted] • BODIPY-MXene nanosheets were fabricated based on electrostatic interaction. • ABS/BODIPY-MXene nanocomposites were prepared via solution blending. • ABS/BODIPY-MXene exhibited improved mechanical performance. • ABS/BODIPY-MXene showed enhanced fire safety properties. [ABSTRACT FROM AUTHOR]

A self-healing coating containing polyethyleneimine (PEI)/ammonium polyphosphate (APP) polyelectrolyte complex was successfully prepared, and then was deposited on flexible polyurethane foam (FPUF) in association with graphene oxide (GO) via a simple dip-nip process to improve the flame retardancy and mechanical property. The vertical burning test revealed that the FPUF coated with PEI/APP and GO extinguished immediately after removing the igniter. The cone calorimeter results demonstrated that the coating effectively reduced the peak heat release rate by 63.8%. The char analysis suggested that PEI/APP formed an intumescent char structure and released inert gases, whilst GO improved the compactness of the char layer. Furthermore, the compressive strength of the coated foam sample was increased by 175.0% compared to that of the control FPUF sample. The mechanical properties analysis and morphology observation proved that the PEI/APP-GO coating had self-healing ability. This unique intrinsic self-healing coating provides a new opportunity for imparting flame retardancy and excellent mechanical property to foam materials used in many commercial cases. [Display omitted] • PEI/APP-rGO was coated on the foam via a dip-nip process. • The coating improved the flame retardancy and eliminated the melt dripping. • The coating significantly increased the mechanical properties. • The coating showed excellent durability and self-healing ability. [ABSTRACT FROM AUTHOR]

Polyurethane (PU) sponge has a wide range of applications in our daily life. Unfortunately, the PU sponge is highly flammable and becomes a breeding ground for bacteria, thereby threatening human health and life. To date, it remains a challenge to improve the flame retardant and antibacterial properties of PU sponge simultaneously without destroying its inherent elasticity and flexibility. Here we report a novel composite coating on the PU sponge using bioderived phytic acid and sodium lignosulfonate via a facile soaking method. Compared to the pristine sponge, the coated PU sponge can reach a 32% reduction in peak heat release rate during cone calorimeter test, and prevent melt dripping after being ignited by a butane torch and the flame can be self-extinguished after the torch is removed. The resultant composite coating also demonstrates a killing rate of 99% against Staphylococcus aureus. Meanwhile, the coated PU sponge can retain the inherent elasticity and flexibility even after 500 cycles of compression. Furthermore, the coating materials are easily recyclable, which provide a useful reference for multifunctional treatment of sponge and cyclic utilization of resources. [ABSTRACT FROM AUTHOR]

Cellulose-based film material, due to its remarkable physicochemical properties, environmentally friend and low cost, has been widely applied in many high-end areas. However, the lack of functional properties (e.g., flame resistance) except poor mechanical performance severely hinders their further applications. Herein, bamboo-based phosphorylated cellulose nanofibrils (B-PCNFs) were prepared through a simple two-step method composed of phosphorylation and mechanical grinding process. The resultant film prepared via solvent casting process shows an excellent mechanical strength of 115.9 MPa, remarkable elongation at break of 53.1%, high Young's modulus of 2.5 GPa and impressive work of fracture up to 41.8 MJ m−3, respectively, which should be contributed to the formation of dense and homogeneous polymer networks reinforced by enhanced multiple interactions. When burned against the flame of alcohol lamp (700–800 °C), B HL -PCNF film also delivers appealing structural stability even over 25s, demonstrating a prominent flame resistance. Meanwhile, compared to original one, the peak heat release rate (PHRR) and total heat released (THR) of B HL -PCNF film produce a dramatical reduction, i.e., 87.3% and 86.6% for PHRR and THR, respectively. Based on the evolution of morphological and chemical structure, the highly improved flame resistance is strongly contributed to the synergy of phosphorus containing group and lignin, resulting in a protective layer composed of P x O y compound and carbon layer. The proposed mechanism for the enhanced flame retardant property is also declared and clarified. Thereby, this phosphorylated cellulose-based film that integrates outstanding mechanical performance and excellent intrinsically flame resistance holds promising potential candidate in practical applications, such as flame-retardant packaging materials. [Display omitted] • Phosphorylated cellulose nanofibrils were prepared through a combination of phosphorylation treatment and mechanical grinding. • The phosphorylated cellulose nanofibril-based films were fabricated via solvent casting method. • The obtained films possessed excellent mechanical performance and outstanding flame resistance. • The flame-retardant mechanism based on the combination of phosphorus containing group and lignin was clarified. [ABSTRACT FROM AUTHOR]

Organic-inorganic hybrid flame retardant technology integrates independent ingredients into a whole, thus showing advantage of simultaneous improvement in flame retardant, smoke suppressant and mechanical properties of polymers over traditional flame retardants. In this work, a novel organic-inorganic hybrid flame retardant denoted as IR-MOF-3-Mel was synthesized by covalent hybridization of isoreticular metal-organic framework-3 (IR-MOF-3) with melamine. A relatively low amount of IR-MOF-3-Mel nanoparticles dramatically decreased the fire risk of epoxy resin (EP). Specifically, the EP with only 2.0 wt% of IR-MOF-3-Mel achieved a limiting oxygen index (LOI) of 30.5% as well as a UL-94 V-0 classification, whereas its counterpart with 2.0 wt% of IR-MOF-3 showed a LOI of 25.0% and no classification in UL-94 test. Furthermore, the peak heat release rate, total heat release and smoke production rate of the EP with 2.0 wt% of IR-MOF-3-Mel was declined by 74.0%, 71.4% and 35.6%, respectively, compared to neat EP. Additionally, the glass transition temperature, the tensile strength, and the young's modulus were 11 °C, 38%, and 27% higher than those of neat EP, respectively. The flame retardant mechanism analysis clarified that IR-MOF-3-Mel contributed to formation of a char layer with a high level of thermal resistance and graphitization which accounted for significantly reduced fire risks. Image 1 • With only 1.5 wt% of IR-MOF-3-Mel, the EP composite achieved a UL-94 V-0 rating. • 2.0 wt% of IR-MOF-3-Mel leads to an unprecedented reduction in both PHRR (−74.0%) and THR (−71.4%) of epoxy composites. • IR-MOF-3-Mel hybrid also shows good smoke suppression effect. • 2.0 wt% of IR-MOF-3-Mel improves the tensile strength by 38% compared to neat EP. [ABSTRACT FROM AUTHOR]

It is always a challenge to improve the flame retardancy of poly (methyl methacrylate) (PMMA) without uncompromised mechanical properties, transparency and other properties. In this research, an organic-inorganic hybrid strategy to prepare flame retardant PMMA with satisfying thermal stability, mechanical properties and transparency, is reported. A new reactive phosphorus containing monomer (MDP) is copolymerized with methyl methacrylate to provide flame retardant function, and meanwhile, octa-vinyl polyhedral oligomeric silsesquioxane (V-POSS) serves as a reinforcer, is chemically combined with the copolymer. The organic-inorganic hybrid copolymerized nanocomposite with 10 mol% MDP and 0.5 mol% V-POSS, shows significantly enhanced limiting oxygen index (LOI), decreased heat release rate compared with PMMA. The flame retardant mechanisms are analyzed and discussed in detail. Additionally, its initial decomposition temperature is increased by 42 °C, showing higher thermal stability. The terpolymer also exhibits greatly improved mechanical property due to the introduction of V-POSS, and its tensile strength, young's modulus and impact strength are much higher than those of MMA-MDP copolymer. Finally, it also keeps good optical property comparable to PMMA. As a result, Our research provides an effective way to prepare intrinsic flame retardant PMMA with good comprehensive performance. Image 1 • Synthesis of a new reactive phosphorus containing flame retardant. • Synthesis of organic-inorganic hybrid plexiglass by ternary copolymerization. • Components collaboration improve multi performance. • Flame retardant mechanism analysis. [ABSTRACT FROM AUTHOR]

In this manuscript, the Layer-by-Layer technique is used to modify the surface of flax fabrics using a quad-layer architecture (QL) prior to their assembly in polylactic acid biocomposites. The aim is to produce nanostructured interphases capable of conferring flame retardancy while maintaining mechanical properties. Only 2.5 QL significantly improve the flame retardancy and fire safety of the prepared composites as demonstrated by LOI values of 25.3%, considerably reduced flame spread rates and the substantial reduction in peak of heat release rate (−33%) and maximum average rate of heat emission (−30%) during cone calorimetry. Mechanical testing showed improved modulus and limited reductions in flexural strength. These results make the approach developed in this manuscript very attractive in the design of advanced biocomposites with optimized fire retardancy and mechanical properties. Image 1 • Layer-by-Layer nanostructured interphases are employed for biocomposites • Flame retardant confinement at the interphase avoids matrix degradation • Improved mechanical and flame retardant properties can be simultaneously achieved [ABSTRACT FROM AUTHOR]

Phosphonate esters may be used as flame retardants for flammable polymers, but always face low flame-retardant efficiency and melt dripping. Until now, no remarkable progress was made in solving the above two defects, thus tremendously affecting their applications as flame retardants. In current work, from the chemistry viewpoint, we designed and synthesized poly(2-butyne-1,4-diol phenylphosphonate) (PPBP) containing alkynyl group to break through above-mentioned defects. Compared with the corresponding control sample poly(1,4-butanediol phenylphosphonate) (PPBOP) without alkynyl, thermal analysis revealed that residual char of the PPBP with C C bonds increased to 45.0%, much higher than 1.6% for the PPBOP without C C bonds, and greatly increased by 27 folds. Various measurements and kinetic analysis were used to investigate the underlying cause for the leap in charring. It turns out that PPBP was involved in a unique decomposing and crosslinking process upon heating, which played a vital role in the leap in charring for PPBP. The leap in charring might afford polymers better flame retardancy through condensed phase. After incorporation of the PPBP into thermoplastic polyurethane (TPU), burning tests illustrated that PPBP not only endowed TPU with excellent flame retardancy and anti-melt dripping performance, but also resulted in extremely low heat release rate and smoke production rate, correspondingly decreased by 70.7% and 53.9% compared with those of TPU. Various measurements further confirmed that the charring caused by PPBP itself and the enhanced charring of TPU induced by PPBP played a crucial role in the remarkable superior flame retardancy of TPU/PPBP. [ABSTRACT FROM AUTHOR]

In order to improve the flame retardancy while maintaining the excellent mechanical properties and heat resistance of epoxy resin, a novel P/N/S-containing high efficiency flame retardant named TAP was designed and synthesized by a simple one-pot reaction among 2-thenaldehyde, 2-aminobenzothiazole (ABZ) and 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO). The chemical structure of TAP was characterized by Fourier transform infrared (FTIR) spectroscopy, 1H and 31P nuclear magnetic resonance (NMR) spectroscopy. Compared to pure EP, the introduction of TAP can reduce the thermal decomposition rate of epoxy resin and increase the char residue. Meantime, when the phosphorus content was only 0.48%, EP/7.5%TAP passed the vertical burning V-0 rating, obtaining a high flame-retardant efficiency. With the addition of 10 wt% TAP, the limiting oxygen index (LOI) value increased from 22.8% of pure EP to 31.5%, while the peak heat release rate (PHRR), total heat release (THR) and total smoke production (TSP) values decreased by 41.26%, 35.70% and 24.03%, respectively. In addition, the glass transition temperature (T g) of the epoxy resin decreased from 185 °C to 177 °C, while the storage modulus at 30 °C increased. Subsequently, the flexural tests of the samples revealed that the mechanical properties were well maintained. All these results demonstrated that the TAP was a novel high efficiency flame retardant for EP, which enabled the cured EP to maintain excellent heat resistance and mechanical properties. • A novel P/N/S-containing heterocyclic halogen-free flame retardant (TAP) for epoxy resin was synthesized. • TAP endows epoxy resin with high-efficiency flame retardancy. • Flame-retardant EP maintains excellent heat resistance and mechanical properties. [ABSTRACT FROM AUTHOR]

N doped carbon nanosheet and B N co-doped carbon (BNC) nanosheet are first prepared through exfoliation of carbon of Schiff based covalent organic frameworks (COFs) under ultrasound using sodium lignin sulfonate as the intercalation agent and modifier. Then poly (vinyl alcohol) (PVA)/BNC nanocomposite with enhanced thermal oxidation stability, good mechanical performances and enhanced flame retardancy has been prepared through solution blending. The temperature at 5 wt% weight loss and peak heat release rate of PVA loaded with 4 wt% of BNC nanosheet increase by 31.9 °C and 57.3% compared with that of untreated PVA, respectively. A new fire hazard evaluation system based on analytic hierarchy process (AHP) is raised to comprehensively estimate fire risk of prepared sample. It is deduced from AHP that PVA loaded with 4 wt% BNC nanosheet shows the lowest fire risk (77.9 score). The effect of BNC nanosheet on pyrolysis mode of PVA in gaseous and condensed phase has also been investigated to figure out the reason for low fire risk of treated PVA. Image 1 • A novel strategy to prepare B and N doped carbon nanosheet derived from covalent organic frameworks. • The PVA/BNC nanocomposite with enhanced thermal oxidation stability and enhanced flame retardancy has been prepared. • A new fire hazard evaluation system based on analytic hierarchy process (AHP) is raised. • The effect of NBC nanosheet on pyrolysis mode of PVA in gaseous and condensed phase has been investigated. [ABSTRACT FROM AUTHOR]

The development of poly(lactic acid) (PLA) composites having flame retardancy, tensile toughness and transparency is the state-of-the-art, which requires meticulous selection and combination of additives. To achieve this goal, an ionic liquid (IL) tetrabutylphosphonium tetrafluoroborate is synthesized and used as a synergist for ammonium polyphosphate (APP). Due to the high synergistic effect between them, only 1.5 wt% IL and 1.5 wt% APP (total amount of 3 wt%) can endow PLA with fire safety, i.e. limiting oxygen index (LOI) of 27.2, UL 94 V-0 rating and low heat release rate of 290 kW m−2. Besides, the elongation at break of PLA containing 3 wt% IL/APP increases from 8.5% of PLA to 204.6%. Meanwhile, the incorporation of IL/APP has tiny impact on the transparency of PLA. The PLA/IL/APP possessing toughness and flame retardancy shows great potentials in the fields of packaging, automotive and electronic and electric industry in the future. Image 1 • A novel ionic liquid (IL) tetrabutylphosphonium tetrafluoroborate is synthesized. • [TBP][BF 4 ] has excellent synergistic effect with APP. • IL/APP endows PLA with excellent fire safety. • IL/APP enhances the tensile toughness and crystallinity of PLA. • Flame-retardant PLA maintains its transparency. [ABSTRACT FROM AUTHOR]

A pyrolysis model capable of predicting materials' fire behavior as a function of concentration was developed for an intumescent flame retardant system: poly(lactic acid) (PLA) blended with melamine (MEL) and ammonium polyphosphate (APP). The model was developed through inverse analysis of data obtained from bench-scale pyrolysis experiments wherein a 0.07-m-diameter disk-shaped sample was exposed to well-defined radiant heating in an anaerobic environment. Sample back surface temperature, sample shape profile and burning rate were measured simultaneously. A numerical pyrolysis modeling framework, ThermaKin2Ds, and a previously developed semi-global thermal decomposition reaction mechanism were employed in the inverse analysis to determine material properties that define the heat and mass transport inside the pyrolyzing solids. The final pyrolysis model was found to predict materials' fire behavior for a variety of thermal exposures and material compositions. The model construction process revealed that a reduction in gas transfer coefficients helped to reproduce certain features of the burning rates profiles. Idealized cone calorimetry scenarios were simulated to study the influence of additives on materials' fire behavior, and the results demonstrated that the blend with 5 wt% MEL and 25 wt% APP was found to be the most effective system with a 69% reduction in the average heat release rate comparing to that of PLA. A similar significant reduction has been reported in the literature, supporting the accuracy of this model. This work demonstrates a methodology that enables intelligent design of intumescent flame retardant materials tailored for specific applications, where low flammability is required. Image 1 [ABSTRACT FROM AUTHOR]

Considering the reduction of fire hazards associated with the application of epoxy resin (EP) composites. Herein, a novel sodium-containing polyhedral oligomeric phenyl silsesquioxane (Na-Ph-POSS) has been synthesized through hydrolysis condensation. FTIR, NMR and MALDI-TOF MS results reveal that Na-Ph-POSS is a hepta-phenyl POSS consisting of Si–O–Na and Si–OH groups. Compared to pure EP, according to the combustion results, the peak of heat release rate (p-HRR), the maximum smoke density (Ds, max) and the peak of CO production rate (p-COP) of EP/5 wt% Na-Ph-POSS significantly decrease by 45.9, 45.1 and 46.9%, respectively. Additionally, EP composites endowed with Na-Ph-POSS have low dielectric constant and dielectric loss. Therefore, eco-friendly multifunctional Na-Ph-POSS provides a promising prospect for mitigating the fire hazards of EP composites. • A novel metal-POSS (Na-Ph-POSS) is firstly synthesized via one-pot method. • Na-Ph-POSS can significantly reduce the diffusion of heat, smoke and CO of EP. • The mechanism of catalytic charring of sodium for EP is firstly illustrated. • Na-Ph-POSS opens a new window for designing halogen-free flame retardants. • Na-Ph-POSS has broad application prospects in the electronics field. [ABSTRACT FROM AUTHOR]

Transition metal oxides based catalytic carbonization have been proved to be a promising way to enhance polymer flame retardancy, but finding better way to introduce organic phosphorus and transition metal oxide hybrids into polymer matrix to form nanocomposites is still a great challenge. In this work, an organic phosphorus and metal oxide hybrid compound named P–MnMo 6 was prepared through combining 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) with polyoxometalate (POM). The as-prepared P–MnMo 6 had a center of [MnMo 6 O 18 ]3- and was used as the precursor of transition metal oxides to improve the flame retardancy of epoxy resin (EP). With the aid of the organic modification, the addition of P–MnMo 6 not only maintained the transparency of EP but also enhanced the dynamic mechanical properties. Notably, the thermogravimetric analysis showed that the char yield of EP/P–MnMo 6 composite increased significantly. Besides, epoxy with 8 wt% addition of P–MnMo 6 passed the vertical burning grade (UL-94) V-0 rating with the limiting oxygen index (LOI) value of 30.4%. Cone calorimeter test indicated the peak heat release rate of EP/P–MnMo 6 -4 decreased by 41%. Meanwhile, smoke products and CO were greatly suppressed. In addition, the potential flame retardancy mechanism of P–MnMo 6 in epoxy matrix was proposed. [ABSTRACT FROM AUTHOR]

A bio-flame retardant filler was synthesized via the self-polymerization of dopamine hydrochloride in alkaline condition, yielding nano-sized polydopamine (nano-PDA) particles ranging between 50 and 100 nm in diameters. Adding a small amount (2 wt%) of the nano-PDA particles into an epoxy can remarkably reduce the value of peak heat release rate by 53.6%, exceeding the performance aluminum trihydroxide (ATH) particles at 10 wt%. The significant improvement in flame retardancy at a relatively low loading of PDA has been found to originate from several key mechanisms including radical scavenging, higher char yield, and production of CO 2. Furthermore, the addition of nano-PDA in the epoxy resin increased the tensile strength by ~6%. In contrast, the addition of common flame retardant, such as ATH, to achieve the same increase in flame retardancy of epoxy would reduce the tensile strength by 22%. This improvement in mechanical properties is attributed to the better bonding between PDA particles with epoxy than ATH with epoxy. [ABSTRACT FROM AUTHOR]

Preparing flame-retardant polyamide 6 (PA6) composites with low addition of flame retardant remained one of the biggest concerns nowadays. In this work, a novel aromatic Schiff base-containing branched polysiloxane (PCNSi) with high thermal stability and great capacity of charring was first synthesized as a self-crosslinking flame retardant, and then PA6/PCNSi composites were prepared through melt blending with different contents of PCNSi. Inspiringly, a sharp reduction of about 48.9% in peak heat release rate (PHRR) was found for PA6 composite with only 6 wt% of PCNSi in contrast with PA6, and serious melt-dipping behavior of PA6 was suppressed totally as 4 wt% of PCNSi was added into PA6. The formation of a self-extinguished layer was considered as the essential factor for reinforcing the flame retardancy of PA6. This layer was generated under the synergistic effects of the cross-linking reaction of Schiff base structure and thermo-oxidative degradation of polysiloxane units in PCNSi. These composites also presented similar mechanical properties to PA6 due to the low addition of PCNSi and good interfacial interactions between PCNSi and PA6. Image 1 • An aromatic Schiff base-containing branched polysiloxane (PCNSi) was prepared as a self-crosslinking flame retardant. • A sharp reduction of 48.9% in peak heat release rate (PHRR) was achieved for PA6 when 6 wt% of PCNSi was added. • The serious melt-dipping behavior of PA6 was suppressed totally only with 4 wt% of PCNSi. • PA6/PCNSi composites still retained the close mechanical properties to PA6. [ABSTRACT FROM AUTHOR]

This work reports our recent effort on the preparation of α-Phenyl-N-(2-propyl-2-hydroxymethyl-1, 3-dihydroxy)-imine-Nickel (Ⅱ) (Ni-MOF) containing polyhydroxy groups and its application in improving the fire performance of PLA composites in combination with ammonium polyphosphate (APP). The flame retardant evaluation revealed that the presence of 1.7% Ni-MOF and 3.3% APP in PLA increased the LOI value to 31.0%, upgraded the UL-94 level to V-0, decreased the peak heat release rate (pHRR), total heat release (THR) and total smoking production (TSP) by 27%, 19% and 50%, respectively, and substantially delayed the time to ignition (TTI) from 67 to 97 s. It was proposed that the flame retardants take effect in both vapor and condensed phases, and Ni-MOF nanosheets can synergistically improve the flame resistance of PLA with APP. The incorporation of Ni-MOF effectively inhibited the deterioration of mechanical properties for PLA composites caused by the presence of APP. • The Ni-MOF nanosheets containing polyhydroxy groups was prepared. • APP and Ni-MOF nanosheets significantly improved the fire safety of PLA composite. • The possible synergistic flame-retardant mechanism of Ni-MOF and APP was proposed. • Ni-MOF effectively improved the mechanical properties of PLA composites. [ABSTRACT FROM AUTHOR]

Firstly cobalt-based metal-organic framework material (Co-MOF) was designed and synthesized; its composition was studied by fourier transform infrared spectroscopy (FTIR) and energy dispersion spectrum (EDS), and the micrographs were observed by scanning electron microscope (SEM). Several burning test results showed that the flame retardant of TPU was obviously improved by the help of combination of 4.5 wt% APP/1.5 wt% Co-MOF. TPU is easily flammable with severe molten drops, so its limited oxygen index (LOI) is only 21.7 and cannot pass any UL-94 grade in vertical burning test. Whereas in TPU/6.0 wt% (4.5APP/1.5Co-MOF) composites, LOI raised to 28.2 and no dripping was produced in vertical burning test, so it passed UL-94 V-0 grade. Similarly, TPU released a large amount of heat and smoke in cone test, peak heat release rate (pHRR) reached 1359 kW m−2 and smoke production rate (SPR) was 0.11 m−2 s−1; however, in TPU/6.0 wt% (4.5APP/1.5Co-MOF) composites, pHRR reduced sharply to 257 kW m−2 and SPR dropped to 0.04 m−2 s−1. Most of all, some mechanical loss caused by the APP were partly recovered by substitutional use of Co-MOF. [ABSTRACT FROM AUTHOR]

Polystyrene sulfonate functionalized graphene nanosheets (PSS@GNS) with high quality (I D /I G = 0.17) were fabricated through electrochemical exfoliation of bulk graphite followed by simple free radical polymerization in water solution, which is a promising strategy for mass production of polymer functionalized graphene. P-styrene sulfonate anions were used to intercalate into the bulk graphite under voltage and also as monomers of the macromolecule modification agents for the exfoliated graphene nanosheets. Besides, benzene rings and carbon double bonds are considered to be able to capture hydroxyl free radicals which produce defects on graphene sheets during electrochemical exfoliation process, thus improve the quality of the exfoliated graphene nanosheets. Then the graphene nanosheets were incorporated into polystyrene (PS) through a solution blending method to reduce the fire hazards and improve mechanical properties of PS resin. According to the results of cone calorimeter, the introduction of functionalized graphene nanosheets into PS reduces heat release rate (decreased by 40%), total heat release (decreased by 35%) and increases the amount of char residues. The flame retardant improvement is attributed to the barrier effect of well-dispersed graphene nanosheets, limiting the mass transfer of the volatile compounds and forming char layers which blocked polymers from heat and oxygen. Meanwhile, the introduction of PSS@GNS into PS also contributed to increase its strength and elongation rate thanks to the pristine properties of graphene nanosheets and their interfacial interaction with the PS matrix. • This method to fabricate functionalized graphene nanosheets in aqueous solution is easy to operate. • Obtained graphene nanosheets with high quality and few defects were functionalized by polystyrene sulfonate. • Fire safety and mechanical strength of the functionalized graphene/polystyrene nanocomposites were improved. • Favorable dispersion, compatibility and interfacial interaction contributed to the enhancement of PS nanocomposites. [ABSTRACT FROM AUTHOR]

Cytosine pyrophosphate (PPA-C) was prepared by using pyrophosphoric acid (PPA) and cytosine (C). The structure, morphology and thermal stability of PPA-C were analyzed by using Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy and thermogravimetric analysis (TGA). The PPA-C was used as acid and gas source and pentaerythritol (PER) as charring agent to form an intumescent flame retardant (IFR) system which was applied to improve the flame retardancy of polypropylene (PP). The flame retardancy and thermal degradation behaviors of PP/IFR composites were investigated by vertical combustion (UL-94), limiting oxygen index (LOI) and cone calorimeter (cone), TGA etc. The PPA-C and PER have good synergistic effects on improving the flame retardancy of PP which is better than that of commercial ammonium polyphosphate (APP) and PER system. The PP/IFR composites with 18 wt% PPA-C/PER (3:1) achieves the UL-94 V-0 rating and a LOI value of 28.8 vol%. The PPA-C reacts with PER to form -P-O-C and -P-C- during combustion which helps the formation of intumescent char layer. In addition, the IFR makes PP degrade in advance and form more char residues at high temperature. Proper ratio and amount of PPA-C/PER promotes the formation of intumescent char layer without defects during combustion, reduces the heat release rate and delays the thermal degradation of PP composites, thus improves the flame retardancy of PP. Cytosine pyrophosphate (PPA-C) and pentaerythritol (PER) show synergistic flame retardant effect on polypropylene (PP) composites. Image 1 • A bio-based flame retardant PPA-C was prepared by using pyrophosphatic acid (PPA) and cytosine (C). • UL-94 V0 rating is achieved for PP composites with 13.5 wt% PPA-C and 4.5 wt% PER. • PPA-C/PER promotes the formation of intumescent char layer without defects. [ABSTRACT FROM AUTHOR]

In order to effectively reduce fire hazards while retaining excellent mechanical properties of flexible polyvinyl chloride (PVC), a novel core-shell-structured flame retardant, i.e., activated carbon spheres-supported NiCo 2 (CO 3) 1·5 (OH) 3 hybrid material (ACS@BNCC), was synthesized and dry-modified by 1-butyl-3-methylimidazolium hexafluorophosphate ionic liquids ([BMIM] PF 6) before mixing with PVC. The results of the limiting oxygen index (LOI) and cone calorimeter test (CCT) showed that 2 phr ILs-ACS@BNCC could endow PVC with outstanding fire-resistant and smoke suppression properties. The synergistic effect of ACS@BNCC and [BMIM] PF 6 increased the LOI to 29.1%, and reduced the peak heat release rate, peak smoke production rate, and total smoke production of pure PVC by 37.0%, 62.0%, and 45.1%, respectively. The flame retardant mechanism was proposed. The 2 phr ILs-ACS@BNCC mainly had physical barrier, catalytic carbonization, endothermic and dilution effects. In addition, since [BMIM] PF 6 enhanced the interface compatibility between PVC and ACS@BNCC, the tensile strength, elongation at break, and impact strength of 2 phr ILs-ACS@BNCC/PVC were significantly improved compared with those of ACS@BNCC/PVC. This kind of PVC composite with outstanding flame retardant, smoke suppression and mechanical properties will substantially expand the application of PVC. Image 1 • A perfect core-shell flame retardant ACS@BNCC was designed and synthesized. • ACS@BNCC and [BMIM] PF 6 exerted a synergistic flame retardant effect in PVC. • The flame-retardant mechanism of ILs-ACS@BNCC was proposed. • The mechanical property of PVC was improved due to the presence of [BMIM] PF 6. [ABSTRACT FROM AUTHOR]