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• A bio-based P/N-based melamine-aggregate (MPA) is prepared for use in PA6. • Combination use of MPA and ADP significantly decreases the heat release of PA6. • Synergistic effects between MPA and ADP at certain ratio are demonstrated. Engineering polyamide 6 (PA6) is preferred for its superior mechanical properties, yet the intrinsic flammability restricts its industrial applications. As one of the biomass phosphorus-containing chemicals, phytic acid (PA) is favorable for its high phosphorus content and aggregation ability, making it expected to enhance the fire retardancy of PA6. Herein, a melamine-phytate aggregate (MPA) is prepared by electrostatic interaction in aqueous solution, and applied as a synergist for aluminum diethylphosphinate (ADP) in PA6. The strong synergistic effect exists between ADP and MPA towards PA6, especially when their mass ratio is 3:1 and the total loading is 18 wt%. Compared to the neat PA6, this formula allows for remarkable decreases in peak heat release rate (PHRR), total heat release (THR), and maximum average heat release rate (MARHE) by ∼ 48 %, ∼ 27 %, and ∼ 30 %, respectively, as well as a high synergistic efficiency of ∼ 43 % in PHRR. This PA6 composite also presents a V-0 rating in the vertical burning (UL-94) test and a high limiting oxygen index (LOI) of 29.7 %. This work offers an eco-friendly strategy for developing bio-based P/N fire-retardant aggregates for fabricating PA6 materials with high fire safety. [Display omitted] [ABSTRACT FROM AUTHOR]

• Atom-economic synthetic strategy of a P/N fire retardant (APN) is developed. • 3 wt% APN significantly improves the fire safety of PLA. • The toughness of PLA increases by 85% but maintaining its tensile strength. Renewable and biodegradable polylactide (PLA) has excellent mechanical strength but is highly flammable which restricts its practical applications. Many phosphorus/nitrogen (P/N)-based flame retardants are effective in PLA, but their high addition loading usually decreases the mechanical strength of the PLA bulk. For polyphosphoramides, despite high fire-retardant efficiency, their chemical synthesis often generates chemical wastes as byproducts. Herein, we report an atom-economic and highly efficient oligomeric P/N fire retardant (APN) prepared using a mild Michael addition polymerization with no byproducts. Using only 3 wt% APN, the resulting PLA exhibits desired fire retardancy including a UL-94 V-0 rating and a limiting oxygen index of 37.6%. Furthermore, the toughness of the fire-retardant PLA increases by 85% compared to pure PLA, with both tensile strength and thermal stability preserved. This work offers an atom-economic strategy for synthesizing highly efficient P/N fire retardants for use in the creation of fire-resistant PLA with robust mechanical properties. Atom-economic synthesis was developed to synthesizing a P/N-containing fire retardant for creating fire-retardant PLA. [Display omitted] [ABSTRACT FROM AUTHOR]

In this work, the organocatalytic strategy for the ring‐opening copolymerization (ROCOP) of 3,5‐anhydro‐D‐xylose oxetane 1and various anhydrides has been demonstrated by use of phosphazene base (P1) and triethyl borane (TEB). The ROCOP proceeds efficiently to generate sugar‐derived polyesters with perfectly alternating sequence distribution, controlled molar masses, and moderate dispersity. These polyesters show good thermal stability (Tmax> 320°C) and adjustable glass transition temperatures (Tg70 ~ 110°C) with the variation of anhydrides. This work provides efficient organocatalyst for the selective copolymerization for biomass‐derived degradable polyesters.

In this work, we report the synthesis and polymerization performances of terpenoid‐derived camphoric anhydride (CA). Utilizing simple organo‐base tBuP2as the catalyst, CA can polymerize with various epoxides by efficient and controlled ring‐opening alternating copolymerization (ROAC) to afford perfectly alternating poly(CA‐alt‐epoxide). Kinetic study shows that the polymerization proceeds following zero‐order dependence on the concentration of CA. The self‐switchable terpolymerization from the mixture of CA, propylene oxide (PO) and ε‐caprolactone (CL) is conducted under the catalysis of tBuP2. First, ROAC of CA and PO is carried out exclusively with benzyl alcohol as initiator. Then, block copolymer (BCP) poly(CA‐alt‐PO)‐b‐PCL is obtained via the sequential polymerizations after the complete consumption of CA. The followed ring‐opening polymerization (ROP) of CL is initiated by the terminal hydroxyl of the ROAC‐resulted poly(CA‐alt‐PO) polyester without external stimulus. During the process, the excess PO compound remains intact. The one‐pot synthesis displays distinct living nature and perfect chemoselectivity. The as‐prepared terpenoid‐derived alternating and BCP's exhibit elevated thermal properties.

• MXene/PP composites are prepared by hot-pressing PP non-woven fabric coated with functionalized MXene. • The final composite exhibits an EMI shielding performance of ∼90 dB (8–12 GHz, thickness ∼400 μm). • The resultant MXene/PP composites are mechanically robust with a superior anti-fatigue capability. • The resultant MXene/PP composites exhibit a self-extinguishing capability. Flame-retardant composites with high electromagnetic interference (EMI) shielding performance are desirable for electronic device packaging. Despite great potential of MXene for high EMI, it still remains a great challenge to develop high-performance flame-retardant polymer/MXene composites with excellent EMI shielding effectiveness because of the poor oxidative stability of MXene. Herein, phosphorylated MXene/polypropylene (PP) composites are prepared by coating phosphorylated MXene on PP fabric followed by spraying polyethylenimine (PEI) and hot-pressing. The phosphorylated MXene proves to be more durable against oxidation than pure MXene due to the protection effect of polyphosphates. Upon hot-pressing, melted PP fibers are fused together at their contact points and thus as-prepared composites are bi-continuous with two interpenetrating phases. The composites show significantly improved thermal stability and flame retardancy relative to pure PP, with a low total heat release (THR) of 3.7 kJ/g and a heat release rate (HRR) of 50.0 W/g, which are reduced by 78% and 87%, respectively. In addition, the composites exhibit a high electrical conductivity of ∼36,700 S/m and an EMI shielding performance of ∼90 dB over the whole frequency range of 8–12 GHz with a thickness of ∼400 μm. The as-developed PP/MXene composites hold great promise for reliable protection of next-generation electronic devices working in complex environments. [ABSTRACT FROM AUTHOR]

An efficient, atom‐economic, oxygen‐tolerant, and water‐tolerant strategy has been established to synthesize cyano‐rich polyesters. Four kinds of organic bases, 1,1,3,3‐tetramethylguanidine (TMG), 4‐dimethylaminopyridine, triethylamine, and 1,5,7‐triazabicyclo[4.4.0]dec‐5‐ene (TBD) were explored for accelerating Michael addition polymerization of malononitrile and 1,4‐butandiol diacrylate. TMG can promote the polymerization efficiently under mild conditions to quantitatively afford polyester with high‐molecular weight and moderate polydispersity. The comparison of the kinetic studies of TMG and TBD reveals that TMG shows better catalytic performance, while the catalysis of TBD brings about oligomers in spite of the higher efficiency at early age of the polymerization. Moreover, other diacrylate compounds could also be quantitatively polymerized to afford polyesters with high molecular weight. When dimethacrylate is chose as the monomer, the polymerization becomes sluggish. All the afforded polyesters display programmable thermal and mechanical properties that are closely related to their chemical structures.

Flame retardants are currently used in a wide range of industry sectors for saving lives and property by mitigating fire hazards. The growing fire safety requirements for materials boost an escalating demand for consumption of fire retardants. This has significantly driven both the industry and scientific community to pursue sustainable fire retardants, but what makes a sustainable flame retardant? Here an overview of recent advances in sustainable flame retardants is offered, and their renewable raw materials, green synthesis and life cycle assessments are highlighted. A discussion on key challenges that hinder the innovation of fire retardants and design principles for creating truly sustainable yet cost‐effective fire retardants are also presented. This short work is expected to help drive the development of sustainable, cost‐effective fire retardants, and expedite the creation of a more sustainable and safer society. Rethinking the pathways to sustainable fire retardants, from the perspective of sustainability, costs, and efficiency.

A graphene oxide (GO)-based smart fire alarm sensor (FAS) has gained rapidly increasing research interest in fire safety fields recently. However, it still remains a huge challenge to obtain desirable GO-based FAS materials with integrated performances of mechanical flexibility/robustness, harsh environment-tolerance, high-temperature resistance, and reliable fire warning and protection. In this work, based on bionic design, the supermolecule melamine diborate (M·2B) was combined with GO nanosheets to form supramolecular cross-linking nanosystems, and the corresponding GO-M·2B (GO/MB) hybrid papers with a nacre-like micro/nano structure were successfully fabricated viaa gel-dry method. The optimized GO/MB paper exhibits enhanced mechanical properties, e.g., tensile strength and toughness up to ∼122 MPa and ∼1.72 MJ/m3, respectively, which is ∼3.5 and ∼6.6 times higher than those of the GO paper. Besides, it also shows excellent structural stability even under acid/alkaline solution immersion and water bath ultrasonication conditions. Furthermore, due to the presence of promoting reduction effect and atom doping reactions in GO network, the resulting GO/MB network displays exceptional high-temperature resistance, sensitive fire alarm response (∼0.72 s), and ultralong alarming time (>1200 s), showing promising fire safety and protection application prospects as desirable FAS and fire shielding material with excellent comprehensive performances. Therefore, this work provides inspiration for the design and fabrication of high-performance GO-based smart materials that combine fire shielding and alarm functions.