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

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

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

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

Flame-retardant and smoke-suppressant expanded polystyrene (EPS) foams were prepared by coating a mixture of thermoplastic phenolic resin (PF) and aluminum hypophosphite (AP) or expandable graphene (EG) onto EPS spheres. The PF reacting with AP by hydrogen-bond interaction formed a facile flame-retardant coating PF/AP, which not only greatly reduced flammability and smoke release, but also remained the thermal conductivities of EPS foams at low level. Compared with those of EPS/PF/EG, EPS/PF/AP could pass the UL-94 test and showed better flame-retardant performances with lower heat release rates and fire growth rates. Especially, the time to ignition (TTI) of EPS/PF/AP achieved 52 s, much higher than those of EPS/PF/EG (9 s) and neat EPS (2 s). Also, the peak of smoke production rate (PSPR) and the total smoke production (TSP) of both composites were significantly reduced, showing an excellent smoke-suppressant performance. The mechanism analysis suggested that the PF/AP coating could form a compact P–O–C cross-linked char layer and effectively protect the matrix from further combusting. Particularly, the EPS/PF/AP had a higher compressive strength and lower thermal conductivity in comparison with EPS/PF/EG. These above results show that the EPS/PF/AP composite has enormous potential in building thermal insulation field. Image 1 • A flame-retardant and smoke-suppressant cell coating was successfully designed and fabricated. • The resultant composites exhibited great flame retardancy and smoke suppression. • The flame-retardant and smoke-suppressant mechanism of the composites was proposed. [ABSTRACT FROM AUTHOR]

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

With the increasing public awareness of safety and the ongoing global legislation on the use of flame retardants, the development of eco-friendly flame-retardant methods has become an urgent issue. In this study, we utilized the room-temperature hydrogen-bonding effect and the high-temperature rearrangement inherent in the functional hydroxyl-containing phenylimide structure to engineer a flame-retardant, high-performance aliphatic polyamide. Remarkably, the obtained polyamide copolymer was exclusively composed of the elemental constituents inherent to polyamide itself, i.e., carbon, hydrogen, oxygen, and nitrogen. As expected, the high-temperature rearrangement along with the corresponding char-forming and end-group-capturing effect significantly improved the flame retardancy of the copolymer, characterized by an UL-94 V-0 rating with great anti-dripping performance, 41% reduction in peak heat release rate and 50% reduction in total heat release. The room-temperature hydrogen bonding largely mitigated the deterioration of the chain symmetry and regularity caused by the incorporation of the monomer, thus resulting in substantial preservation of mechanical properties. Furthermore, the copolymer exhibited low dielectric properties and high heat resistance, thereby broadening its potential application domains. This work presented a novel flame-retardant-free strategy for achieving both flame retardancy and high performance in polymeric materials, meeting the increasingly stringent demands for environmental protection and safety. [Display omitted] • A flame-retardant aliphatic polyamide with high performances was successfully obtained. • Favorable mechanical performance was achieved through the room-temperature hydrogen-bonding effect. • The high-temperature rearrangement contributed to a significant enhancement in flame retardancy. • The resultant polyamide exhibited low dielectric properties and high heat resistance. • The condensed-phase char-forming flame-retardant mechanism were confirmed by both experimental and simulation results. [ABSTRACT FROM AUTHOR]

• Novel SiO 2 /PUF composites were designed and fabricated. • The composites with hierarchical pores showed excellent thermal insulation. • The composites exhibited great flame-retardancy and smoke-suppression. • The flame-retardant mechanism of the composites was proposed. Polyurethane foam (PUF) is widely used in building insulation field but highly flammable. In an effort to develop an efficient way to reduce flammability and smoke release of PUF without sacrificing its inherent merits, a novel strategy has been proposed to decorate silica aerogels onto the surface of PUF to fabricate hierarchically porous SiO 2 /PUF composites. Due to the unique hierarchically porous structure, the resultant composites showed superior thermal insulation with a lower thermal conductivity of 0.0282 W/(m K). The introduction of silica aerogels also effectively improved the compressive strength, almost 220% of that of neat PUF. Notably, the SiO 2 /PUF composites were rendered self-extinguishing in vertical burning tests and had a high limiting oxygen index (LOI) value of 32.5%. Cone calorimetry (CC) tests revealed that the peak heat release rate (PHRR) and peak smoke production release (PSPR) of the SiO 2 /PUF composites were reduced by 40.4% and 45.6%, respectively. Particularly, the specific optical density (Ds) of the composites displayed as 55.7% reduction in the smoke density chamber tests, showing excellent smoke-suppression. The mechanism analysis suggested that a compact silica-rich hybrid barrier formed, preventing thermal degradation products and energy transfer during combustion. These results indicate SiO 2 /PUF composites have enormous potential as building insulation materials. [ABSTRACT FROM AUTHOR]

• Single component phosphamide-based intumescent flame retardant with reactivity to epoxy group was synthesized. • Fire safety of epoxy resin with phosphamide-based intumescent flame retardant was greatly enhanced. • The release of smoke and toxic gases such as CO/CO 2 was remarkably inhibited. • The mechanical property of flame-retardant epoxy resin was maintained to some extent. • The mechanism of phosphamide-based intumescent flame retardant was well investigated. To develop a low flammability and smoke epoxy resin, benzothiazole-based phosphamide (DOP-ABZ) was prepared through the reaction of 2-chloro-5,5-dimethyl-1,3,2-dioxaphosphinane-2-oxide (DOP) and 2-aminobenzothiazole (ABZ). Intumescent flame-retardant (IFR) epoxy thermosets (EP) with different loadings of DOP-ABZ were prepared according to the assigned curing procedure. The thermal stability of IFR-EP decreased as compared to that of EP, but the flame retardancy of IFR-EP were greatly improved. EP/20 wt% DOP-ABZ passed UL-94 V-0 rating and got a high LOI value of 28.3%. Meanwhile, cone calorimeter tests showed that the heat release rate greatly decreased from 1139.7 kW/m2 of EP to 238.9 kW/m2, and the productions of smoke/toxic gases including CO and CO 2 were also remarkably reduced. Furthermore, the mechanical strength of EP/17.5 wt% DOP-ABZ was enhanced to some extent, i.e. tensile strength increased from 71 MPa of EP to 81 MPa, flexural strength from 98 to 119 MPa, and impact strength from 22 to 32 kJ/m2. Finally, the flame-retardant mechanism was disclosed that DOP-ABZ produced phosphorus-containing acids so as to dehydrate and carbonize epoxy macromolecules leading to the formation of graphitized chars. Meanwhile, the nitrogen/sulfur-containing intermediates simultaneously released noncombustible gases to expand the as-formed char, and then interrupt the combustion reaction. [ABSTRACT FROM AUTHOR]

Cellulose-based paper is widely used in cultural communication, art appreciation, and cultural relic protection, but is susceptible to fire and mildew. Traditional protective materials have negative impacts on the appearance, flexibility, and writability of paper, resulting in severely limited applications. Herein, we demonstrate a quick and effective approach for enhancing the flame retardancy, antibacterial, and antifungal properties of cellulose papers by assembling polyhexamethylene biguanide (PHMB) and sodium polyphosphate (PSP). By exploiting hydrogen bonding and electrostatic interactions, PHMB and PSP can assemble into micro-nano protuberances that are deposited on the surface of the paper through a 30 s dip-treating technology. The PHMB/PSP layers promote the formation of char layer when exposed to flame, providing the paper with self-extinguishing property with a limiting oxygen index value of 34.5 % and an 84.0 % reduction in peak heat release rate. Meanwhile, the treated papers exhibit excellent antibacterial activity against S. aureus (>99.99 %) and appreciable fungal resistance against T. viride (Grade 1). Importantly, the treatment does not alter the appearance, mechanical stability, and writability of the paper. Owing to the mild conditions and fast processability, this study promotes the wide development of advanced high-performance cellulose paper with combined fire-safety, antibacterial, and antifungal properties for diverse applications. [Display omitted] • A flame retardant, antibacterial and antifungal cellulose paper is prepared. • Micro-nano protuberances are formed by a quick 30 s dip-treating technology. • The performance improvements come from the phosphorus‑nitrogen synergism. • The treatment does not alter the appearance and flexibility of the cellulose paper. [ABSTRACT FROM AUTHOR]

A novel approach for improving the flame retardancy, smoke suppression and mechanical properties of epoxy resins (EPs) has been proposed by incorporating functionalized hollow mesoporous silica microcapsules (SHP) loaded with phosphorous silane flame retardants (SCA) and coated with polydopamine (PDA) and transition metals. The proposed approach involves a multi-level structure that combines several mechanisms to enhance the flame-retardant properties of EP. The physical barrier provided by silica serves to impede heat and mass transfer during combustion, while the catalytic carbonization effect of phosphorus and transition metals promotes the formation of a protective char layer, which acts as a barrier to further flame propagation. Incorporating a low loading amount of 3 wt% SHP into the epoxy matrix resulted in EP/SHP-3 composites with significantly improved flame retardancy, as evidenced by a limiting oxygen index of 31.5% and a V-1 rating, in contrast to the values obtained for unmodified EP, which were 23.8% and no rating, respectively. In addition, cone calorimeter test (CCT) results indicated that the total heat release, peak heat release rate and total smoke production of EP/SHP-3 decreased by 18.2%, 25.2% and 18.4%, respectively. Moreover, the improved interfacial compatibility facilitated by polydopamine assists in the dispersion and compatibility of the SHP with the epoxy matrix, leading to better mechanical properties. Herein, the addition of 1 wt% SHP to EP significantly improved its mechanical performance, with a 16.7% increase in tensile strength and a 19.2% increase in impact strength. The design of the multi-level structural approach has the potential to provide new ideas for the simultaneous improvement of fire safety as well as mechanical properties of polymers. [Display omitted] • Phosphorus-containing silane flame retardants was loaded into the cavity structure of hollow mesoporous silica (HMS) to fabricate HMS microcapsule. • The resultant HMS microcapsule showed both high flame retardancy and mechanical reinforcement for EP. • HMS simultaneously decrease release of toxic gases (such as CO) for EP. • The specific flame-retardant mechanism was analyzed. [ABSTRACT FROM AUTHOR]

• Novel flame-retardant bio-based long-chain aliphatic polyamide with great overall properties. • The copolymer exhibited high LOI value of 32.6%, and achieved an UL-94 V-0 rating. • Successful inhibition of the release of heat and toxic gasses in cone calorimetry test. • The copolymer showed largely improved t g and maintained thermal and mechanical properties. Bio-based long-chain aliphatic polyamides show remarkable potential in pursuing high-performance, sustainable bio-plastics. However, the aliphatic structure also leads to high flammability that severely restricts their applications. Herein, we demonstrate a novel flame-retardant system to fabricate high-performance, flame-retardant bio-based long-chain aliphatic polyamide. In this system, a novel reactive nitrogen-based flame-retardant monomer, PDB, was designed and synthesized. Subsequently, the corresponding bio-based long-chain polyamide copolymer was prepared through a facile polycondensation process. The nitrogen-based groups exhibited highly efficient free-radical-capturing effect, helping the copolymer achieve a high limiting oxygen index value of 32.6%, the UL-94 V-0 rating, a 33.3% lower peak heat release rate, and inhibited the release of toxic gasses at a PDB content of 6 wt%. Furthermore, the copolymer exhibited largely maintained crystallinity, thermal stability, and mechanical properties, owing to the high reactivity of PBD with polyamide monomers. At the same time, the incorporation of PBD increased the rigidity of the copolymer, resulting in a significant increase of 16.4 °C in the glass transition temperature and lower dielectric properties. This work provides a new perspective on the preparation of bio-based long-chain aliphatic polyamide with enhanced overall properties. [ABSTRACT FROM AUTHOR]

[Display omitted] • A new P/Cu-hybrid silica aerogel is developed for flame-retarding and smoke-suppressing polyurethane foam. • The aerogel-containing composite foam has greatly improved thermal insulation. • The incorporation of the aerogel realizes the improvement of compressive strength of the composite foam. • The multiple synergistic of the aerogel enables the composite foam with flame retardancy and smoke suppression. The frequent occurrence of fires caused by rigid polyurethane foam highlights the importance of its fire safety, however, the existing flame-retardant methods often seriously deteriorate the mechanical properties and thermal insulation of the foam. Here, we demonstrate a new idea for thermal insulation, flame retardancy, smoke suppression, and reinforcement of polyurethane foams only by incorporating a P/Cu-hybrid silica aerogel. This unique aerogel combines with the carbon-promoting action of P, catalytic attenuation of Cu, and the barrier effect of aerogels, thus leading to high smoke-suppressing and flame-retardant efficiency for polyurethane foam. At a low addition amount of 5 wt% aerogel, the total heat release, peak heat release rate, total smoke release, and toxic CO production of the composite foam are all significantly reduced. Interestingly, the aerogel-containing composite foam exhibits a special hierarchical porous structure, which enables lower thermal conductivity and higher thermal insulation than pure RPUF. Benefitting from the good compatibility and nano-enhancing effect of the aerogel, the compressive strength of the composite foam remarkable increase of 52.2%. This research offers an effective method for designing high-performance foam materials with high fire safety and low thermal conductivity, which has broad application prospects in the field of thermal insulation. [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]

With the rapid development of 5G technology, functional coatings with both high-efficiency flame retardancy and electromagnetic interference shielding (EMI) are urgently needed, while traditional inefficient methods have encountered bottlenecks. Herein, we demonstrate an eco-friendly and multifunctional nano/micro coating constructed by biomass phytic acid (PA) induced polymerization and self-assembly of polyaniline (PANI) nanoparticles and dip-coating of silver microwires (AgMWs). In this design, PA with high flame-retardant efficiency is smartly doped into PANI to achieve P-N synergistic flame retardancy and improve electrical conductivity of PANI simultaneously. Consequently, under the coaction of AgMWs, P-doped PANI nanoparticles, as well as unique continuous micro-nano structures, the nano/micro coating can endow commercial polyurethane (PU) foams with outstanding EMI shielding performance (∼51 dB in X-band). Meanwhile, the coated PU foam exhibits high flame retardancy due to the P-N synergistic effect of PA/PANI, which self-extinguishes immediately after ignition during the UL-94 vertical burning test, shows a high limiting oxygen index (LOI) value of 34.8%, and exhibits a 50.7% lower peak heat release rate compared with pure PU foam. Further, the functional nano/micro coating with three-dimensional and highly porous structure makes the foam thermally insulating and infrared stealthing. The eco-friendliness and simplicity of this method and its successful application in commercial PU foam make it potentially applicable for the preparation of various kinds of multifunctional EMI shielding materials. [Display omitted] • A multifunctional coating was constructed via the PA-induced polymerization and self-assembly of polyaniline nanoparticles. • The conductive coating endowed the PU foam with an EMI SE value of 51 dB in X-band. • High flame retardancy and low heat release were realized by the phosphorus-containing coating. • The EMI shielding and flame-retardant mechanism were comprehensively investigated. [ABSTRACT FROM AUTHOR]

Biomass-derived aerogels have received extensive attention as potential thermal management materials for energy-efficient buildings. However, it remains a huge challenge to fabricate a fully bio-based aerogel with excellent mechanical property, flame retardancy, and low thermal conductivity. Herein, we demonstrate a novel and facile strategy to manufacture a fully biomass-based aerogel from naturally abundant ammonium alginate (AL) and phytic acid (PA), in which PA acting as both flame retardant and cross-linking components constructs a strong network with AL matrix. Consequently, the resultant biomass aerogel with a low density of 0.052 g/cm3 exhibits ultrahigh mechanical modulus (25.1 ± 3.1 MPa) and specific modulus (440.4 ± 54.4 MPa cm3·g−1), much superior to those of biomass aerogels ever reported. Due to the existence of the uniform three-dimensional porous network, the biomass aerogels exhibit low thermal conductivity (34–38 mW/m·K) and excellent thermal insulation performances. Further, the introduction of PA endows the aerogel with high flame retardancy (limiting oxygen index value of 57%, UL-94 V-0 rating, and extremely low heat release), while the biodegradability of the materials keeps at a high level with a biodegradation rate of 91.43%. Combining with the advantages of mechanically strong property, high flame retardancy, excellent thermal insulation, and biodegradation, the aerogel of this work provides a new strategy to fabricate thermal insulation materials with high environmental safety. [Display omitted] [ABSTRACT FROM AUTHOR]

In order to develop high-performance epoxy resins (EP), a novel phosphorus/nitrogen-containing phenylsiloxane macromolecule (DP-PPD) has been synthesized as a multi-functional additive. The DP-PPD macromolecules can simultaneously enhance the mechanical strength, flame retardancy, and smoke suppression performance for EP at low loading. Compared with unmodified EP, only by introducing 2 wt% DP-PPD, the impact strength, flexural strength and flexural modulus are greatly increased by 100%, 12.9% and 38.7%, respectively, due to flexible phenylsiloxane units and covalent interaction with EP matrix. Meanwhile, the resultant EP containing barely 3 wt% DP-PPD reaches V-0 rating in UL-94 test and shows a high limiting oxygen index of 30.1%. The cone calorimeter test results reveal that the peak of heat release rate, total heat release, and total smoke release of 9%DP-PPD/EP are decreased by 31.4%, 35.4%, and 20.0%, respectively, compared to those of unmodified EP. The mechanism analysis confirms that abundant aromatic rings, siloxane, and DOPO units in DP-PPD can synergistically promote the formation of P–Si-containing hybrid char layer for EP resins during combustion, thus leading to satisfied flame retardancy and smoke suppression. Meanwhile, the reduction of volatilized organic products and the emergence of phosphorous fragments indicates the flame inhibition effect of DP-PPD. Moreover, DP-PPD has little negative effect on the heat resistance of EP. This efficient single-component multi-functional additive provides a new strategy for the construction of high-performance macromolecular materials. Image 1 • A P/N-containing phenylsiloxane macromolecules (DP-PPD) was successfully synthesized. • DP-PPD showed highly efficient flame retardancy and smoke suppression in epoxy resins. • DP-PPD significantly improved mechanical properties of epoxy resins at an ultra-low loading. • The corresponding functional mechanism was revealed in detail. [ABSTRACT FROM AUTHOR]