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Graphite anode materials and carbonate electrolyte have been the top choices for commercial lithium-ion batteries (LIBS) for a long time. However, the uneven deposition and stripping of lithium cause irreversible damage to the graphite structure, and the low flash point and high flammability of the carbonate electrolyte pose a significant fire safety risk. Here, we proposed a multifunctional electrolyte additive diphenylphosphoryl azide (DPPA), which can construct a solid electrolyte interphase (SEI) with high ionic conductivity lithium nitride (Li3N) to ensure efficient transport of Li+. This not only protects the artificial graphite (AG) electrode but also inhibits lithium dendrites to achieve excellent electrochemical performance. Meanwhile, the LIBS with DPPA offers satisfactory flame retardancy performance. The AG//Li half cells with DPPA-0.5M can still maintain a specific capacity of about 350 mAh/g after 200 cycles at 0.2 C. Its cycle performance and rate performance were better than commercial electrolyte (EC/DMC). After cycling, the microstructure surface of the AG electrode was complete and flat, and the surface of the lithium metal electrode had fewer lithium dendrites. Importantly, we found that the pouch cell with DPPA-0.5M had low peak heat release rate. When exposed to external conditions of continuous heating, DPPA significantly improved the fire safety of the LIBS. The research of DPPA in lithium electrolyte is a step towards the development of safe and efficient lithium batteries. [ABSTRACT FROM AUTHOR]

Herein, piperazine phosphoramide derivatives (PPDO) and titanium carbide modified by hexadecyl trimethyl ammonium bromide (c-Ti3C2) were blended with epoxy resin (EP) to fabricate EP/c-Ti3C2/PPDO nanocomposites. According to thermogravimetric analyzer (TGA) results and pyrolysis kinetic analysis, EP/c-Ti3C2/PPDO nanocomposites can improve the thermal stability and the activation energy of EP. Furthermore, thermal degradation mechanism of EP and its nanocomposites with conversion between 0.55 and 0.99 conforms to the F3 model. With 1 wt% c-Ti3C2 and 3 wt% PPDO incorporated, the LOI value of EP/c-Ti3C2-1/PPDO-3 can reach up to 32% while achieves V-0 rating in the UL-94 test. Based on the cone calorimeter results, the peak heat release rate of EP/c-Ti3C2-1/PPDO-3 reduced by 40.1%. More continuous and dense phosphorus-rich char residues were produced for EP/c-Ti3C2-1/PPDO-3 nanocomposites, which can act as a physical barrier to hinder the heat transfer, protect the underlying polymers from further decomposition and isolate the diffusion of combustible gases. The synergistic effect between c-Ti3C2 and PPDO in catalytic carbonization obviously accounts for the improved flame retardant performance. This work provides an insight into the flame retardant mechanism and the thermal degradation mechanism of c-Ti3C2 and PPDO on EP, showing a promising application potential of c-Ti3C2 and PPDO in enhancing the thermal stability and flame retardancy of EP. [ABSTRACT FROM AUTHOR]

Cardanol-derived phenalkamines with different phosphorus oxidation states (Car-DCP-DETA and Car-DPC-DETA) were synthesized by the Mannich reaction and used as curing agents for diglycidyl ether of bisphenol A (DGEBA)-type epoxy prepolymers. 1H-NMR, 31P-NMR and FTIR spectra confirmed that Car-DCP-DETA and Car-DPC-DETA were successfully synthesized. DGEBA/Car-DCP-DETA and DGEBA/Car-DPC-DETA thermosets were fabricated by thermally induced polymerization, while DGEBA/DDM was prepared as a control sample. The curing kinetics investigation indicated that the curing activation energy of the DGEBA/Car-DCP-DETA and DGEBA/Car-DPC-DETA systems was higher than that of DGEBA/DDM because of the larger steric hindrance of Car-DCP-DETA and Car-DPC-DETA. The cone calorimetry results showed that the peak heat release rate (PHRR) values of DGEBA/Car-DCP-DETA and DGEBA/Car-DPC-DETA were 76.8% and 44.8% lower than that of DGEBA/4,4′-diaminodiphenylmethane (DDM), respectively, and the total heat release (THR) value was reduced to 125.8 and 105.8 MJ m−2, respectively, from 159.9 MJ m−2 (DGEBA/DDM). These results suggested a superior flame-retardant efficiency for Car-DCP-DETA over Car-DPC-DETA. The flame-retardant mechanisms of DGEBA/Car-DCP-DETA and DGEBA/Car-DPC-DETA were studied by thermogravimetric analysis coupled with Fourier transform infrared spectroscopy, scanning electron microscopy, Raman spectroscopy and X-ray photoelectron spectroscopy. It can be inferred that the outstanding flame retardancy of DGEBA/Car-DCP-DETA is mainly ascribed to the formation of thermally stable phosphorus–oxygen structures in the combustion process, which is helpful in improving the thermal oxidation resistance of char residues and thus improving the flame retardancy of epoxy resins. Tensile and flexural test results showed that Car-DCP-DETA also had good strengthening and toughening effects on DGEBA. This phosphorus-containing cardanol-derived phenalkamine (Car-DCP-DETA) imparted simultaneously improved flame retardancy, and mechanical strength and toughness to epoxy thermosets, which could be a renewable replacement for petroleum-based curing agents in fire-resistant or corrosion-resistant coating applications. [ABSTRACT FROM AUTHOR]

Severe flame retardancy and poor impact resistance of epoxy resins (EPs) have become key factors limiting their industrial application. Herein, a strategy is developed to integrate nitrogen‐rich black phosphorus (BP) loaded with cerium oxide via aryl diazonium chemistry to reduce the flame risk of the EPs. Cone test results exhibit that the fire hazard of EPs containing 2 wt.% BP‐NHH‐Ce is suppressed effectively, such as that total heat release rate (THR) is reduced by 46.9%, the peak heat release rate (pHRR) is reduced by 56.2%, and the total smoke production (TSP) is reduced by 48.9%. With only 1.0 wt.% of the BP‐NHH‐Ce added, the nanocomposite can reach up to 30.5 of LOI value and simultaneously upgrade the UL‐94 rate to V‐0. In addition, the nano‐structure is beneficial to stress transfer and homogenization, which leads to significant elevation (28.2%) for the impact strength of EPs. This developed new EP/BP‐NHH‐Ce nanocomposite merits the high‐end field application of EPs. [ABSTRACT FROM AUTHOR]

In this work, microcrystalline cellulose (MCC) treated polyamide 66 (PA66) textiles were coated with green and naturally abundant polysaccharides specifically, chitosan (CS) and sodium alginate (SA) together with phytic acid (PA) via layer by layer (LbL) deposition. The prime focus of such treatment was to intensify both the hydrophilic and flame retardant properties of PA66 fabric substrates. Subsequently, the prepared coatings were further subjected to cross-linking modification by dipping them into the barium (Ba) salt solution. Obtained results indicated that the MCC-modified PA66 exhibited a water contact angle (WCA) value of 00 and revealed a drop in peak heat release rate (pHRR) up to 31 % with complete suppression of melt-dripping. Meanwhile, the Ba-ion-induced cross-linking treatment further escalated this reduction up to 36 % by adding enhanced thermal stability, improved char quality along better wash durability of as prepared coatings. In addition, the combined modification of PA66 textiles with MCC and Ba-ion handed a superb enhancement of physical properties like tensile strength by ca. 50 % compared to the pure PA66. Thus, this MCC-assisted surface modification paves the way for a new kind of greener treatment of PA66 textiles in attaining superior hydrophilic and flame retardant properties of the same. • MCC-assisted surface engineering of PA66 fabrics was done. • Green polysaccharides were deposited on PA66 surfaces in LbL assembly. • MCC-modified and LbL deposited fabric surfaces exhibited superhydrophilicity. • MCC-modified and LbL deposited showed a substantial reduction in pHHR by 36 %. • Ba ion cross-linking helped to obtain superior wash durability to developed coatings. [ABSTRACT FROM AUTHOR]

• A syringaldehyde derived epoxy resin monomer (SA-TAG-EP) was developed. • The bio-based epoxy system showed a record T g of 224 °C, high strength and modulus. • The bio-based epoxy system showed satisfactory intrinsic flame retardancy. Due to increasing environmental concerns, global warming, and the decline of oil reservoirs, the use of bio-epoxy resins derived from sustainable resources is recommended. The development of bio-based epoxy resins with considerable thermal stability, mechanical strength, and appropriate intrinsic flame retardant potential is highly demanded. In this study, a new Schiff-based epoxy monomer, triglycidyl ether of syringaldehyde (SA-TAG-EP), was synthesized from renewable syringaldehyde. After the 4,4′-diaminodiphenylmethane (DDM)-based curing process, an intrinsically flame-retardant resin (SA-TAG-EP/DDM) with C, H, N, and O elements was achieved. SA-TAG-EP/DDM showed higher glass transition temperature (224.9°C) and greater mechanical strength, including a tensile strength of 66.8 MPa and an elongation at break of 3.91%, compared to petroleum-based bisphenol A epoxy thermoset. It also passed the V-0 flammability rating in the UL-94 test and exhibited a 38.5% limiting oxygen index, 48.9% char yield under N 2 , and a lower peak heat release rate than that of petroleum-based bisphenol A epoxy thermoset. We proposed a simple and sustainable route for the synthesis of Schiff base epoxy compounds from biomass-derived resources, which demonstrates significant mechanical properties and increased flame retardant potential. [ABSTRACT FROM AUTHOR]

[Display omitted] • FPUF composites was formed after the introduction of Ti 3 C 2 T x @BPA@PCL and DH-DOPO. • Compression strength of FPUF-DH-Ti 3 C 2 T x @BPA@PCL are increased by 253% and is highly fatigue-resistance. • 36.1% and 44.0% reductions in pHRR and THR of FPUF-DH-Ti 3 C 2 T x @BPA@PCL are achieved. • FPUF-DH-Ti 3 C 2 T x @BPA@PCL is self-extinguished and passes the vertical burning test. It is of great importance to fabricate flexible polyurethane foam (FPUF) with superior mechanical properties and flame retardancy for practical applications. Herein, organosilicon and phenyl phosphorus compounds were synthesized and grafted on the surface of Ti 3 C 2 T x (Ti 3 C 2 T x @BPA@PCL) via in-situ polymerization. Then, the FPUF composites were fabricated, combining intrinsic flame retardancy (9,10-dihydro-9-oxa-10-phosphaphenanthrene 10-oxide-diethanolamine: DH-DOPO) (addition amount: 20 wt%) and Ti 3 C 2 T x @BPA@PCL (addition amount: 4 wt%). Attributed to the rigid structure of Ti 3 C 2 T x @BPA@PCL, the tensile strength and compression strength of FPUF showed 24.0% and 253% increase, respectively. In addition, anti-fatigue properties of FPUF composites during the cyclical test were dramatically enhanced. In contrast to pure FPUF, 36.1% and 44.0% reductions in peak heat release rate (pHRR) and total heat release (THR) were achieved for the FPUF containing Ti 3 C 2 T x @BPA@PCL and DH-DOPO, the production rate of carbon dioxide (CO 2) and carbon oxide (CO) also decreased by 40.3% and 52.1%, respectively. FPUF4 showed self-extinguishing behavior, and passed the vertical burning test (VBT). This work provides a facile approach to preparing high-performance FPUF with enhanced mechanical property and flame retardancy. [ABSTRACT FROM AUTHOR]

• A series of coatings with high transparency and excellent pencil hardness levels were prepared on polycarbonate (PC) substrates via a two-step UV-curing process with TAEP and MAAR. • The coupling effect of the combustion behaviours of the UV-cured coatings and the PC substrates was particularly investigated to give insight into a holistic picture of the combustion of the coated PC composites. • The composite UV-cured coatings successfully suppressed the heat release and improved the flame retardancy of the PC samples thanks to the phosphorus-nitrogen synergistic flame-retardant effect in the condensed phase. • A potential strategy to further enhance the flame-retardant ability of the UV-cured coatings lies in improving the thermal and mechanical stabilities of the intumescent char layers. There is an urgent demand for flame retardant treatment of polycarbonate (PC) with as little adverse impact on the inherent advantages of PC as possible, especially the high transparency. Herein, a flame-retardant coating with high transparency was successfully prepared on PC via a two-step ultraviolet-curing (UV-curing) process with tri(acryloyloxyethyl) phosphate and melamine acrylate resin. All the coated PC composites showed high transparency and excellent pencil hardness levels (6H). The coupling effect of the combustion behaviours of the UV-cured coatings and the PC substrates was particularly investigated to give insight into a holistic picture of the combustion of the coated composite systems. Specifically, all the composite UV-cured coating samples (T2M1, T1M1 and T1M2) formed highly expanded char with honeycomb-like inner structure due to the phosphorus-nitrogen synergistic effects, which could efficiently suppress mass and heat transfer, thereby protecting the PC substrates from the harsh conditions of high temperature and realizing significantly enhanced flame retardancy of the PC samples. Improving the thermal and mechanical stabilities of the intumescent carbon layers may be a practical strategy to achieve further improved flame retardant capabilities of the PC samples. Additionally, the PC-T2M1 composite exhibited the optimal flame retardant effect, realizing significantly suppressed heat release in the cone calorimeter tests, reaching UL94 V-0 rating and showing long fire resistance time thanks to the intumescent char. The UV-cured coating method introduced in this work had great potential in spawning new strategies for designing advanced flame retardant coatings for polymer substrates. [Display omitted] [ABSTRACT FROM AUTHOR]

• An organic-inorganic hybrid flame retardant (THPSU-MMT) was synthesized. • EP-MMT composites have good flame retardancy and comprehensive properties. • The thermal decomposition of EP-MMT composites was studied. • It provides a green and efficient method for exfoliation of montmorillonite. Traditional additive flame retardants pose issues including high dosage, easy precipitation, and poor compatibility with the matrix. Designing efficient organic-inorganic synergistic flame retardants can enhance the flame retardancy and mechanical properties of epoxy (EP) composites while reducing their smoke toxicity. In our study, we initially employed Tetrakis(hydroxymethyl)phosphonium sulfate (THPS) for intercalation modification of montmorillonite (MMT). Subsequently, we achieved a green and efficient exfoliation of MMT by reacting urea with hydroxyl groups, resulting in the simultaneous preparation of efficient organic/inorganic synergistic flame retardants (THPSU-MMT). EP composites containing 5wt% THPSU-MMT can attain UL-94 V0 classification. Furthermore, the peak heat release rate (PHRR), total heat release (THR), and peak release rates of CO can be reduced by up to 78.42 %, 62.26 %, and 72.50 %, respectively. Simultaneously, we systematically investigated the synergistic flame retardant mechanism of the EP composite. The findings reveal that THPSU-MMT exhibits a dual flame retardant effect in both the gaseous and condensed phases. Moreover, the combination of MMT and THPSU substantially enhances the presence of phosphorus-containing pyrolysis products in the condensed phase. The fire performance index (FPI) of the flame retardant EP increased from 0.05 m2/s/W in pure EP to 0.36 m2/s/W, attributed to the enhanced catalytic carbonization and assisted gas-phase free radical capture. Additionally, the flame spread index (FGI) decreased from 11.55 kW/m/s in pure EP to 1.18 kW/m/s, signifying a substantial enhancement in fire safety. Furthermore, the THPSU-MMT synergistic flame retardants improved the tensile strength of EP composites. This study offers an environmentally friendly and efficient approach for the effective exfoliation of MMT, while also presenting novel concepts for the design of efficient organic-inorganic synergistic flame retardants. [Display omitted] [ABSTRACT FROM AUTHOR]

Epoxy resin (EP) is quite flammable, which limits its application in areas such as coatings and electronic and electrical materials. In this study, 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) (or diphenylphosphine oxide (DPO)) 3-cyclohexene-1-formaldehyde (CC) and 4,4'diaminodiphenylmethane (DDM) were selected for the synthesis of two rich aromatic and phosphorus-containing compounds (DOPO-CC and DPO-CC). DOPO-CC and DPO-CC were introduced into epoxy pre-polymers to prepare epoxy thermosets with flame retardancy. When 5 wt% DOPO-CC (P content of 0.50 wt%) or DPO-CC (P content of 0.52 wt%) was added, the LOI values of the epoxy thermosets increased from 25.5% (pure EP) to 33.5% (EP added DOPO-CC) and 31.0% (EP added DPO-CC), respectively, and these epoxy thermosets also achieved the UL-94 V-0 rating. Additionally, cone calorimeter tests showed that the peak heat release rate (PHRR) and total heat release (THR) of epoxy thermoset containing 5 wt% DPO-CC reduced by 42.0% and 39.7% compared to those of pure EP, respectively. By reducing the thermal degradation rate (condensed phase) and combining and quenching free radicals (gaseous phase), the introduction of DOPO-CC or DPO-CC can efficiently improve the flame retardancy of epoxy thermosets. More importantly, the epoxy thermosets containing DOPO-CC or DPO-CC exhibited better mechanical properties than pure EP, which could be proven by the storage modulus and tensile strength. This study provided a new class of rich aromatic and phosphorus-containing compounds that can serve as co-curing agents for epoxy thermosets with outstanding comprehensive performances. [Display omitted] • Two rich aromatic and phosphorus-containing compounds (DOPO-CC and DPO-CC) were synthesized. • EP containing 5 wt% DOPO-CC or DPO-CC showed UL-94 V-0 level. • The PHRR and THR of EP containing 5 wt% DPO-CC decreased by 42.0% and 39.7%, respectively. • EP containing DOPO-CC or DPO-CC exhibited better mechanical properties than pure EP. [ABSTRACT FROM AUTHOR]

The demand for "green" materials increases due to concerns about the effects of flame-retardant textiles. Using natural plant-base compounds such as phytic acid (PA) and the most abundant green amino polysaccharide chitosan (CS) as effective and durable flame retardants for textiles is essential for creating sustainable and ecological textile products. This study aims to develop a novel, eco-friendly, phosphorus- and nitrogen-containing flame retardant known as ammonium phytate (AP), intending to improve the flame retardant properties of polyamide 6.6 (PA6.6) textiles. UV-induced grafting with 2-acrylamide-2-methylpropane sulfonic acid (AMPS) increases the surface functional groups of PA6.6 fabrics. Later, the surface-modified fabrics were coated with phosphorus-containing heteroatom-based components, namely, sulfur, nitrogen, silicon, and boron, onto a single flame retardant system via layer-by-layer (LBL) deposition of positively charged chitosan/boron drop (3-aminopropyl) triethoxysilane/silicon dioxide (CS/BAPTES/SiO 2) sole solution and negatively charged AP solution to enhance superior hydrophilic and durable flame retardant performance. According to the data, a weight pick-up of 56.5% is attributable to only 4 BLs. However, all the flame-retardant-coated fabrics can completely stop the melting-dripping tendency and achieve B-3 to B-2 ratings after the UL-94 vertical burning test. In addition, the LOI values of treated fabrics increase from 18.5% to 23.5% compared to a pure sample. The AMPS grafted with a 4BL-deposited fabric sample exhibits a maximum decrease in peak heat release rate (PHRR) of more than 54%. Moreover, the thermogravimetric analysis (TGA) test reveals a significant increase in thermal stability and char yield. Additionally, the as-prepared phosphorus-containing heteroatom-based coatings impart a water contact angle value of approximately 0⁰ within 2 s, demonstrating that the treated fabrics exhibit superior hydrophilic performance. Moreover, using AMPS-grafted and only 2-BL-deposited treatments improves coating stability in washing and imparts durable flame retardancy that can resist up to 20 washing cycles. It is proposed that the sustainable phosphorus-containing heteroatom-based coating may be a potentially effective replacement for existing durable flame retardants routinely used in textile finishing operations. [Display omitted] • UV-induced grafting of AMPS onto the PA6.6 fabric surfaces was done. • A P-containing heteroatom-based coating was applied successfully. • A maximum reduction in PHRR of over 54% was realized in only 4BL-deposited fabric samples. • An improvement in the superior hydrophilic fabric surfaces was attained. • Only 2 BLs of finishing treatment could stop the melt-dripping tendency even after 20 washing cycles. [ABSTRACT FROM AUTHOR]

• The smart fabric cotaing was prepared using a one-step process. • A solid, fire-resistant gel serves as the host skeleton. • A solid–liquid switchable phase change functional guest. • The fabric effectively responds to changes in ambient temperature. The stability of personal thermal management are increasingly indispensable in modern society due to the growing demand for energy savings and environmental protection. Herein, inspired by solid–liquid host–guest materials, we propose a coating preparation strategy that uses a solid flame-retardant gel as the host skeleton filled by a solid–liquid switchable phase change flame-retardant functional guest, thus fabricating smart polyester fabrics for personal temperature management in one step. Both attenuated total reflectance (ATR) and scanning electron microscopy (SEM) are used to confirm the host–guest structure coating on the surface of polyester fabric. Results from simulated cold and heating environments show that the coated polyester fabric has a desirable personal temperature regulation ability. The skin wrapped by the coated polyester fabric presents a higher temperature compared with bare polyester fabric, in simulated cold conditions. Meanwhile, in heating conditions, the internal temperature of the coated polyester fabric is 5.2 oC lower than that of the bare polyester fabric. Furthermore, the coated polyester fabric exhibits excellent flame retardancy in the combustion test, with a horizontal burning rate of 85.7 mm/min and a peak of heat release rate (PHRR) reduction of 52.8 %, attributed to higher graphitization degree and suppressed pyrolysis products. For promoting the practical application, the water vapor transmission, washing resistance, and mechanical performance are also deeply studied. Hence, a phase-change flame-retardant polyester fabric constructed with a host–guest structure provides huge application potentials in various personal temperature management fields, such as snow rescue, field camping, and adventure activities. [ABSTRACT FROM AUTHOR]

Rising concerns about the toxic effects and environmental issues associated with various fireproof treatments on textiles have led to a demand for "green" materials. Chitosan (CS) is an amino polysaccharide green, recyclable, and non-toxic highly biocompatible biopolymer that consists of multiple hydroxyl groups and has a wide range of applications, including as a flame retardant additive. In this study, an eco-friendly bio-based formaldehyde-free flame retardant containing a higher level of phosphorus and nitrogen in phytic acid ammonia (PAA) was synthesized to amplify the most plentiful green chitosan (CS)-modified polyamide 66 (PA66) fabric surface through a simple pad-dry-cure technique for the improvement of durable flame retardancy with hydrophilicity. The findings revealed that each UV-grafted CS fabric could entirely stop the melt-dripping tendency during the vertical burning (UL-94) test and reached a V -1 rating. Meanwhile, limiting oxygen index (LOI) testing showed a rapid increase from 18.5 % to 24 % for the PA66 control and the PAA-treated (i.e., PA66-g-5CS-PAA) fabric samples, respectively. Moreover, compared to the PA66 control sample, a dramatic decrease in the peak heat release rate (PHRR), fire growth rate (FGR), and total heat release (THR) by approximately over 52 %, 0.63 %, and 19.7 %, respectively, was observed for the PA66-g-5CS-PAA fabric sample. Additionally, this arrangement of PAA catalyzed the charring of grafted CS and acted as a condensed phase flame retardant, resulting in a significant improvement in char yield% in both air and N 2 atmospheres for the PA66-g-5CS-PAA fabric sample in TGA. In addition, only the lower grafting ratio of CS with PAA-treated fabric sample (i.e., PA66-g-2CS-PAA) could encourage it to gain its lowest water contact angle of 00, as well as impersonating a positive effect in improving the flame retardant coating durability in washing and sustaining even after 10 home laundering cycles. This phenomenon suggests that an actual hydrophilic and durable flame retardant finishing procedure for polyamide 66 fabrics might be applied with the novel, plentiful, sustainable, and environmentally friendly bio-based green PAA ingredient. [ABSTRACT FROM AUTHOR]

• A vanillin-derived bisDOPO co-curing agent (DVD) was successfully synthesized from vanillin and DOPO. • The introduction of DVD improved the mechanical properties of epoxy thermosets. • Epoxy with an ultra-low P content of 0.42 wt% exhibited an LOI of 30.5% and reached a UL-94 V-0 rating. To prepare transparent and flame-retardant epoxy thermosets, a vanillin-derived bisDOPO co-curing agent (DVD) was synthesized from vanillin and DOPO. The influence of DVD on the curing kinetics of the epoxy systems was investigated by non-isothermal differential scanning calorimetry (DSC). The introduction of DVD increased the activation energy of the curing process. Compared with pure epoxy, the storage modulus at 30 °C and tensile strength of EP/DVD-5% increased by 35.7% and 145%, respectively. Additionally, the epoxy thermosets still maintained excellent transparency. The addition of DVD improved the flame-retardant performance of epoxy thermosets by promoting the formation of char and reducing the thermal decomposition rate. Most importantly, DVD showed high flame retardant efficiency for the resulting epoxy thermosets. Specifically, with the incorporation of 5 wt% DVD (only 0.42 wt% phosphorus loading), the resulting epoxy thermoset exhibited a limiting oxygen index (LOI) value of 30.5% and reached a UL-94 V-0 rating. The cone calorimetry results showed that the total heat release (THR), peak value of heat release rate (PHRR), and total smoke production (TSP) of EP/DVD-5% decreased by 32%, 42%, and 21%, respectively, compared with the unmodified EP. The modes of action of flame retardant analysis indicated that DVD exhibited high flame retardant efficiency by serving as a charring promotor in the condensed phase and acting as a radical scavenger in the gaseous phase. The above results demonstrate that DVD is a promising flame retardant agent to render epoxy thermosets simultaneously improved flame retardancy, mechanical strength and transparency. [ABSTRACT FROM AUTHOR]

[Display omitted] • Phthalocyanine-zirconium polyphosphazene functionalized BP was obtained by crosslinking reaction. • BP-ZrPZN effectively reduced the total smoke release decreased by an impressive 62.7 %. • BP-ZrPZN can comprehensively improve the fire safety and mechanical properties of EP. The existence of lone pair electrons on the surface of black phosphorus (BP) is a good electron acceptor, which has good structural stability when it forms new electron donor-electron acceptor pairs when combined with electron donators such as phthalocyanine. In order to bond functional groups available for reaction on the surface of BP, the lamellae group density was increased by functionalizing BP with benzoic acid diazonium salt, and then the carboxylated BP was covalently grafted with phthalocyanine zirconium, and finally the phthalocyanine-zirconium polyphosphazene functionalized BP (BP-ZrPZN) was obtained by crosslinking reaction. Subsequently, BP-ZrPZN was added into the EP matrix as nano filler to form the reinforced system. The results showed that the thermal stability and fire safety of EP composites containing 2 wt% BP-ZrPZN were significantly improved. The peak heat release rate and total heat release rate were reduced by 56.8 % and 54.1 %, respectively, and the limited oxygen index was up to 33 % and UL94 value was V-0. In addition, the presence of BP-ZrPZN greatly improved the ability of BP to inhibit toxic smoke. The total smoke yield of EP composites decreased by 62.7 %. The tensile strength and impact strength increased by 36.1 % and 50.6 % respectively. Therefore, the functional strategy of phthalocyanine in this work will provide a reasonable and feasible way to optimize the flame retardancy and smoke suppression effect of BP. [ABSTRACT FROM AUTHOR]

As one of the most widely used polymers, the intrinsic brittleness and high flammability bring about a stringent requirement for the practical application of epoxy resins (EPs). It is difficult to toughen EP without compromising its mechanical and thermal properties for many conventional toughening agents. Here, a novel furan-derived bio-based polyphosphazene (PFMP) with a flexible backbone and rigid side groups was prepared by the nucleophilic substitution reaction between polydichlorophosphazene (PDCP) and furfuralcohol. The resultant PFMP was incorporated into EP to realize exceptional toughening, strengthening, and flame retardant function. By adding 15% of PFMP, the limit oxygen index value is from 25% (EP) to 33% (EP/PFMP-15) and reaches the UL-94 V-0 rating. According to the cone calorimeter results, EP/PFMP-15 exhibits exceedingly reduced peak heat release rate (pHRR) (50.2%) and total heat release (THR) (49.6%). The significantly increased fire performance index (FPI) and decreased fire growth rate index (FIGRA) of EP/PFMP-15 demonstrate an improvement in its flame retardancy. The catalytic carbonization effect (condensed phase) and radical quenching effect (gas phase) of PFMP account for the greatly improved flame retardancy. Moreover, the impact and tensile tests indicate that PFMP can ameliorate the mechanical performance of EP with a maximum increase of impact strength (111.8%) and elongation at break (35.2%) for EP/PFMP-5. With 15% PFMP added, the tensile strength of EP/PFMP-15 increases by 40.4%. This work demonstrates that PFMP is expected to overcome shortcomings (flammability, toughness, and strength) of EP and spread its applied fields. [Display omitted] • Bio-based polyphosphazene with furfuralcohol side groups (PFMP) was synthesized. • PFMP exhibits evident flame retardant and mechanical enhancement effect on epoxy resins (EP). • The peak heat release rate of EP/PFMP-15 was 50.2% lower than pure EP. • The impact strength of EP/PFMP-5 was 111.8% higher than pure EP. [ABSTRACT FROM AUTHOR]

[Display omitted] • A new flame retardant DOPONH 2 -S was synthesized. • It solved the problems of epoxy resin (EP) including flammability and brittleness. • DOPONH 2 -S achieved high efficiency in reducing THR, P -HRR and EHC of EP. • DOPONH 2 -S increased the impact strength and thermal stability of EP. Epoxy resin (EP) has two shortcomings: flammability and brittleness. Previous studies have improved brittleness or flame retardancy but they will compromise the glass transition temperature (T g) and thermal stability. Herein, a novel DOPO based phosphorus-, nitrogen- and sulfur-co-contained macromolecular flame retardant (DOPONH 2 -S) was synthesized and incorporated into EP to improve its flame retardancy and toughness with not damaging T g and thermal stability. After curing, both T g and the tensile strength of EP-2 improved at the addition of DOPONH 2 -S is 6.75 wt%. Simultaneously, the thermogravimetric analysis (TGA) results showed DOPONH 2 -S is helpful increasing the thermal stability of EP composites and protecting the polymer from further decomposition. In the fire safety test, EP-2 achieved V-0 rating in the vertical burning test and obtained a limiting oxygen index value of 30.5%. In comparison with pure EP, the peak heat release rate, total heat release and effective heat of combustion of EP-4 incorporated with 10.0 wt% DOPONH 2 -S were reduced by 59.1%, 58.5% and 46.3%, respectively. A two-phase mechanism was discussed to explain the combination effect in DOPONH 2 -S. In condensed-phase, rich char residue prevents the exchange of mass and heat during combustion. It also obstructs the release of combustible gases into the combustion zone. In gas-phase, the produced phosphorus- and sulfur-containing free radicals can capture active free radicals (H· and OH·), thus ending the chain reaction of combustion. Moreover, the addition of DOPONH 2 -S apparently improved the impact strength (62.5%). This work provided ideas for the development of multifunctional EP. [ABSTRACT FROM AUTHOR]

[Display omitted] • Utilizing the flame retardancy advantages of polyphosphazene and melamine, PPM was firstly designed and synthesized. • PPM has a positive effect on enhancing the fire safety and mechanical properties of BMI. • PPM is an integrated intumescent flame retardant and the cooperation effect of polyphosphazene and melamine in PPM is revealed. In view of the problems of poor toughness and high fire risk of bismaleimide (BMI), a novel maleimide-functionalized triazine-rich polyphosphazene microsphere (PPM) was designed and prepared in this work by combining the flame retardant advantages of polyphosphazene and melamine. The functionalization of organic maleimide in PPM can improve the interfacial compatibility between PPM and BMI. With addition of 2.0 wt% PPM, the peak value of heat release rate (PHRR) and total smoke production (TSP) of BMI/PPM-2.0 decrease by 52.8 % and 30.8 %, respectively, while its impact strength increases by 97.5 %, which means that the fire safety and toughness of BMI/PPM are much better. The study on flame retardant mechanism of PPM reveals that PPM has obvious condensed-phase intumescent flame-retardant effect, which may be due to the similar composition of PPM and intumescent flame retardant. In addition, PPM has the phosphorus-oxygen radical flame-retardant effect in gas phase and also has the toughening effect of inorganic rigid particles on BMI performance. [ABSTRACT FROM AUTHOR]

• Cardanol-derived anhydride cross-linked epoxy thermosets achieved UL-94 V-0 grade. • A remarkable reduction in the PHRR value of 47.7% was observed. • Cardanol-derived anhydride imparted excellent toughness to the cured epoxy. • Cardanol-derived anhydride cross-linked epoxy showed high shape recovery efficiency of more than 96% With the increasing awareness of environmental protection, the development of high-performance bio-based epoxy resins has attracted more and more attention to reduce the dependence on the petroleum-based 4,4′-diaminodiphenylmethane (DDM). In this work, we synthesized two kinds of cardanol-based curing agents (Car-DCP-MAH and Car-DPC-MAH) as alternatives for petroleum-based DDM. The chemical structures of Car-DCP-MAH and Car-DPC-MAH were confirmed by 1H and 31P NMR. Compared with the traditional DGEBA/DDM thermoset, the cured DGEBA/Car-DCP-MAH and DGEBA/Car-DPC-MAH thermosets both displayed good intrinsic fire resistance in terms of higher LOI values (29% and 28%, respectively, versus 24.5%) and V-0 rating in the UL-94 test. Furthermore, the results of the cone calorimeter test showed a significant reduction in the peak heat release rate (PHRR) values of the cured DGEBA/Car-DCP-MAH and DGEBA/Car-DPC-MAH which were 42.3% and 47.7%. The flame retardancy of these two systems was mainly due to the great carbonization ability and the formation of the intact and compact char layer. Owning to the flexible long alkyl chain in the crosslinking network, the toughness of the cured DGEBA/Car-DCP-MAH and DGEBA/Car-DPC-MAH products was greatly improved with the higher elongation at break and impact strength. Additionally, the cured DGEBA/Car-DCP-MAH and DGEBA/Car-DPC-MAH thermosets both showed preferable shape memory properties with a high shape recovery efficiency of 98.6% and 96.3%. This study provides a novel strategy to achieve bio-based epoxy thermosets with intrinsic anti-flammability, toughness and shape memory effect. [ABSTRACT FROM AUTHOR]

[Display omitted] • The polyaniline (PANI) is deposited on the surface of two-dimensional Ti 3 C 2 to obtain the Ti 3 C 2 @PANI hybrid for constructing waterborne polyurethane (WPU) composite. • Due to the existence of conductive fillers and the isolated structure, the electromagnetic shielding effectiveness of Q-FBP-WPU/Ti 3 C 2 @PANI composite is still higher than 20 dB after hundreds of stretching and bending. • The cone test results show that the peak heat release rate of Q-FBP-WPU/Ti 3 C 2 @PANI is decreased by 46.2%. To solve the increasing serious electromagnetic radiation pollution and limitations of metal-based electromagnetic shielding materials in flexible devices, the polyaniline (PANI) is deposited on the surface of two-dimensional Ti 3 C 2 to obtain the Ti 3 C 2 @PANI hybrid for constructing waterborne polyurethane (WPU) composite. Meanwhile, to address the flame risk of WPU composite, the two-dimensional black phosphorous (BP) is incorporated as a flame retardant to prepare isolated flame-retardant black phosphorous-waterborne polyurethane/Ti 3 C 2 @polyaniline(Q-FBP-WPU/Ti 3 C 2 @PANI) composite with isolated structure. Due to the existence of conductive fillers and the isolated structure, the Q-FBP-WPU/Ti 3 C 2 @PANI composite exhibited the highest electrical conductivity (2.23 S/m) and the electromagnetic shielding effectiveness (EMI SE) of 27.3 dB in the frequency range of 8.2–12.4 GHz (X-band) and retains higher than 20 dB after hundreds of stretching and bending, which completely satisfies the commercial demands. Compared with the composite with a disordered structure, the thermal conductivity of Q-FBP-WPU/Ti 3 C 2 @PANI is increased by 93.3%. The cone test results show that the peak heat release rate, total heat release, total smoke production and total CO production of Q-FBP-WPU/Ti 3 C 2 @PANI is decreased by 46.2%, 16.3%, 21.2% and 15.5% than that of pure WPU, certifying the fire safety of WPU are greatly improved. This work supports a novel and applicable idea for constructing functional electromagnetic shielding materials. [ABSTRACT FROM AUTHOR]

• A vanillin-derived cyclotriphosphazene-cored triazole compound (HHCTP) was synthesized. • The HHCTP-modified epoxy achieved a UL-94 V-0 classification and an LOI of 31.5%. • The addition of HHCTP preserved the thermo-mechanical properties of epoxy resins. A vanillin-derived cyclotriphosphazene-cored triazole compound (HHCTP) was successfully synthesized as a flame retardant for epoxy thermosets with high efficiency while preserving their thermomechanical properties. 1H- and 31P nuclear magnetic resonance (NMR), as well as Fourier Transform infrared (FT-IR), were applied to confirm the molecular structure of HHCTP. The dynamic mechanical analysis (DMA) measurements demonstrated that the introduction of HHCTP improved the storage modulus of the epoxy composites but decreased the glass transition temperature. The epoxy thermoset containing 7.5 wt% HHCTP (EP/HHCTP-7.5) achieved a UL-94 V-0 classification and an LOI of 31.5%, manifesting its outstanding flame-retardant efficiency. In addition, the cone calorimeter results showed that the total heat release (THR) and the peak value of the heat release rate (PHRR) of EP/HHCTP-7.5 were decreased by 35.6% and 50.0%, respectively, in comparison with those of the unmodified epoxy. To further study the flame retardant mechanism of HHCTP, pyrolytic gas species were detected utilizing thermogravimetric-infrared spectroscopy (TG-FTIR). In addition, the microstructure of the char residues was analyzed via X-ray photoelectron spectroscopy (XPS) and scanning electron microscope (SEM) techniques. The phosphazene groups in HHTCP clearly stimulated the production of an intumescent, compact, and strong char layer, which improved the flame retardancy of the DGEBA matrix during burning, according to the SEM data. As a result, the underlying components were protected from further degradation and combustion, resulting in effective flame retardancy of the DGEBA thermoset. [ABSTRACT FROM AUTHOR]

Taking into consideration the frigid and thunderstorms, the flame retardancy and de-icing performance are simultaneously desiderated for some open-air key equipment, such as air fuselage and wind turbine blades. Here, inspired by the anti-reflection phenomenon of moth eyes and cicada wings, a multi-functionalized and biomimetic MXene@SnO 2 hierarchical nanostructure is prepared to effectively impart flame retardancy and solar de-icing performance to thermoplastic polyurethane (TPU) resin used widely as the finishing coat of protective materials of open-air equipment. Based on the catalytic effect and barrier function, the addition of hierarchical MXene@SnO 2 nanostructures also effectively decreases the release of heat and toxic smoke from PU resin, as confirmed by reductions of 50.5% and 33.1% in the peak heat release rate and smoke production rate, respectively. Due to the appropriate refractive index, the light reflection phenomenon is effectively suppressed, thus promoting solar absorption (∼90% at 0.4 mm film) and photo-thermal conversion (∼74.2 °C with simulated solar illumination of 1.0 kW/m2) in TPU-MXene@SnO 2 nanocomposites. Within the environment of −20 °C, the surface temperature of TPU-MXene@SnO 2 nanocomposites is still up to 32.7 °C and the surface ice pellet begins to melt at ∼40s, much earlier than 600s of pure TPU resin. In addition, the practical application of functionalized TPU nanocomposites is further improved by the higher mechanical properties, attributed to the strong interfacial interaction. Inspired by moth eyes and cicada wings, flame retardancy and solar de-icing performance are first integrated into polymer materials, thus effectively promoting their application in some extreme environments. [Display omitted] [ABSTRACT FROM AUTHOR]

Towards simultaneously improving the moist ambient stability and flame retardancy efficiency of black phosphorus (BP) nanosheets, cross-linked polydimethylsiloxane (PDMS) is simultaneously synthesized and grafted onto the surface of BP nanosheets, thus obtaining hydrophobicity to shield the water molecule and synergistic flame retardant effect. Compared to badly damaged morphology of pure BP nanosheets, the well-ordered crystal structure confirms that PDMS-BP nanosheets are moist-environmentally stable. With the grafting of PDMS, BP nanosheets present higher flame retardancy efficiency to thermoplastic polyurethane (TPU). The reductions of 59.6% and 14.3% are presented in peak heat release rate (PHRR) and total heat release (THR) of TPU resin, compared with pure TPU. The CO 2 and CO produced by resin combustion are also decreased by 42.8% and 29.3%, indicating lower gas toxicity. Based on the morphology observation and element analysis of char residue, the synergistic effect between phosphorus and silicon elements is responsible for the flame retardancy improvement. Such a route simultaneously provides a valuable reference for moist-environmentally unstable nanomaterials and develops the practical application of BP nanosheets in polymer composites fields. [Display omitted] • Cross-linked PDMS bonds with BP nanosheets by noncovalent interaction. • Moist ambient stability is imparted to BP nanosheets. • Fire safety and water resistance of polymer are enhanced simultaneously. • Heat, smoke, and toxic CO during polymer combustion are greatly decreased. [ABSTRACT FROM AUTHOR]

A novel carbon fiber/MXene coalition (CF-Ar-MXene) is synthesized via a bidirectional aryl diazonium chemistry method using p-phenylenediamine as a chemical bridge, which effectively combines the two materials with different dimensions and makes full use of the advantages of both. CF-Ar-MXene coalition materials achieve high surface roughness and rich oxygen-containing active groups due to the presence of MXene on the surface of CF, which leads to the favorable interfacial interaction and compatibility between CF-Ar-MXene and epoxy resin (EP) matrix. As expected, after the incorporation of CF-Ar-MXene coalition into EP matrix, the flame retardancy and mechanical properties of EP composites are significantly improved. For example, with the addition of 3 wt% CF-Ar-MXene coalition, the peak heat release rate (PHRR), total heat release (THR) and total smoke production (TSP) of EP composites decrease by 42.6%, 48.2% and 32.1%, respectively. Meanwhile, the TG-IR results indicate that the amount of combustible volatile products and toxic gases also significantly decrease. Notably, with 2 wt% loading of CF-Ar-MXene coalition in EP composites, the tensile strength and elongation at break increase by 49.9% and 40.5%, respectively. Therefore, the efficient cooperation between CF and MXene in CF-Ar-MXene coalition and excellent interface compatibility with EP matrix are the main reasons for the excellent flame retardancy and mechanical properties of EP/CF-Ar-MXene composites. [Display omitted] • CF-Ar-MXene coalitions were prepared by a bidirectional aryl diazonium chemistry method for the first time. • The method used in this experiment is efficient and eco-friendly compared with the traditional modification method for CF. • CF-Ar-MXene coalitions achieved high filler efficiency in reducing the fire hazards and smoke production of EP. • Mechanical properties of EP/CF-Ar-MXene composites were efficiency enhanced. [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]