Phosphorus and nitrogen supramolecule for fabricating flame-retardant, transparent and robust polyvinyl alcohol film.

Supramolecular flame retardants have attracted increasing attention recently due to their simple and eco-friendly preparation process. In this study, a novel flame retardant HEPFR was prepared using supramolecular self-assembly technology between piperazine and 1-hydroxy ethylidene-1,1-diphosphonic acid (HEDP). It was introduced into polyvinyl alcohol (PVA) matrix to form PVA/HEPFR composite film.

Overcoming the barrier: designing novel thermally robust shape memory vitrimers by establishing a new machine learning framework.

Shape memory vitrimers (SMVs) are an emerging class of advanced materials that have garnered significant interest from researchers in the past five to six years. These materials can return to their original shape when exposed to a stimulus, while also healing damage they have sustained. However, achieving both high healing/recycling efficiency and a high glass transition temperature () in SMVs has been challenging, due to the conflicting requirements between molecular chain mobility and the formation and reaction of dynamic covalent bond exchange.

Eco-Friendly One-Pot Supramolecular-Assembly of P-N Flame Retardant for Fire-Safe Epoxy Resin.

Flame retardant treatment of epoxy resins (EP) to reduce their flammability for extending their range of applications attracts considerable attention. However, the synthesis process of conventional flame retardants is complicated and involves organic hazardous solvents. Meanwhile, how to ensure both the flame-retardant and mechanical properties is a long-standing and actual difficult problem.

Synthesis and Applications of Supramolecular Flame Retardants: A Review.

The development of different efficient flame retardants (FRs) to improve the fire safety of polymers has been a hot research topic. As the concept of green sustainability has gradually been raised to the attention of the whole world, it has even dominated the research direction of all walks of life. Therefore, there is an urgent calling to explore the green and simple preparation methods of FRs.

Facile Ball Milling Preparation of Flame-Retardant Polymer Materials: An Overview.

To meet the growing needs of public safety and sustainable development, it is highly desirable to develop flame-retardant polymer materials using a facile and low-cost method. Although conventional solution chemical synthesis has proven to be an efficient way of developing flame retardants, it often requires organic solvents and a complicated separation process. In this review, we summarize the progress made in utilizing simple ball milling (an important type of mechanochemical approach) to fabricate flame retardants and flame-retardant polymer composites.

Research Progress in Preparation, Properties and Applications of Biomimetic Organic-Inorganic Composites with "Brick-and-Mortar" Structure.

Inspired by nature, materials scientists have been exploring and designing various biomimetic materials. Among them, composite materials with brick-and-mortar-like structure synthesized from organic and inorganic materials (BMOIs) have attracted increasing attention from scholars. These materials have the advantages of high strength, excellent flame retardancy, and good designability, which can meet the requirements of various fields for materials and have extremely high research value.

Konjac Glucomannan Aerogels Modified by Hydrophilic Isocyanate and Expandable Graphite with Excellent Hydrolysis Resistance, Mechanical Strength, and Flame Retardancy.

At present, biomass foamlike materials are a hot research topic, but they need to be improved urgently due to their defects such as large size shrinkage rate, poor mechanical strength, and easy hydrolysis. In this study, the novel konjac glucomannan (KGM) composite aerogels modified with hydrophilic isocyanate and expandable graphite were prepared by a facile vacuum freeze-drying method. Compared with the unmodified KGM aerogel, the volume shrinkage of the KGM composite aerogel (KPU-EG) decreased from 36.

Surface Flame-Retardant Systems of Rigid Polyurethane Foams: An Overview.

Rigid polyurethane foam (RPUF) is one of the best thermal insulation materials available, but its flammability makes it a potential fire hazard. Due to its porous nature, the large specific surface area is the key factor for easy ignition and rapid fires spread when exposed to heat sources. The burning process of RPUF mainly takes place on the surface.

A novel approach simultaneously imparting well-hydrophobicity and photothermal conversion effect to polymer materials: solar-promoted absorption of organic solvents and oils.

In this work, a series of polymer materials including pomelo peel, cotton fabric, polyurethane foam, and so on, are treated by heated CHSiCl, presenting desirable photo-thermal conversion function and hydrophobicity. As a representative material, the surface element and skeleton morphology of pomelo peel foam treated by CHSiCl are analyzed detailedly. It is found that well-hydrophobicity (water contact angle of ~147°) and photo-thermal conversion performance (~91.

A Thermoset Shape Memory Polymer-Based Syntactic Foam with Flame Retardancy and 3D Printability.

Here we report a thermoset shape memory polymer-based syntactic foam inherently integrated with flame retardancy, good mechanical properties, excellent shape memory effect, and 3D printability. The syntactic foam is fabricated by incorporating a high-temperature shape memory polymer (HTSMP) as the matrix, with 40 vol % hollow glass microspheres (HGM) K20, K15, and K1 as fillers. Compressive behavior, strain-controlled programming followed by free recovery, stress recovery, and flame retardancy of these three syntactic foams were studied.

From Drug Molecules to Thermoset Shape Memory Polymers: A Machine Learning Approach.

Ultraviolet (UV)-curable thermoset shape memory polymers (TSMPs) with high recovery stress but mild glass transition temperature () are highly desired for 3D/4D printing lightweight load-bearing structures and devices. However, a bottleneck is that high recovery stress usually means high . For a few TSMPs with high recovery stress, their values are close to the decomposition temperature, and thus, the shape memory effect cannot be triggered safely and effectively.

Room-Temperature Self-Healable and Mechanically Robust Thermoset Polymers for Healing Delamination and Recycling Carbon Fibers.

The advocacy of carbon neutrality and circular economy encourages people to pursue self-healing and recycling of glassy thermoset polymers in a more realistic and energy-saving manner, the best being intrinsic healing under room temperature. However, the high mechanical robustness and healing ability are mutually exclusive because of their completely opposite requirements for the mobility of the polymer networks. Here, we report a dual-cross-linked network by slightly coupling the low-molecular-weight branched polyethylenimine with an ester-containing epoxy monomer in a nonstoichiometric proportion.

Versatile Phosphate Diester-Based Flame Retardant Vitrimers via Catalyst-Free Mixed Transesterification.

We herein report a new vitrimer system integrated with UV curability, recyclability, and flame retardancy. Energy-efficiency, sustainability, and safety have been required features for next-generation polymer materials. Various attempts have been made to endow thermoset polymers with rapid prototyping capacity, recyclability, and flame retardancy.

Multireusable Thermoset with Anomalous Flame-Triggered Shape Memory Effect.

While thermosets with high mechanical properties and shape memory capabilities have been developed in recent years, two main bottlenecks persist in their intrinsic nonreusability and flammability, especially for those shape memory thermosets used in recycling-required field with high glass transition temperatures ( T) and thus risky high temperatures to trigger shape recovery. Here, we report a new shape memory epoxy thermoset integrated with excellent fire retardancy, recyclability, high mechanical performance, and 100% shape recovery ratio. The shape memory effect of this new thermoset was directly triggered by high-temperature flame for the first time.

Mussel-inspired functionalization of electrochemically exfoliated graphene: Based on self-polymerization of dopamine and its suppression effect on the fire hazards and smoke toxicity of thermoplastic polyurethane.

The suppression effect of graphene in the fire hazards and smoke toxicity of polymer composites has been seriously limited by both mass production and weak interfacial interaction. Though the electrochemical preparation provides an available approach for mass production, exfoliated graphene could not strongly bond with polar polymer chains. Herein, mussel-inspired functionalization of electrochemically exfoliated graphene was successfully processed and added into polar thermoplastic polyurethane matrix (TPU).

Melamine-containing polyphosphazene wrapped ammonium polyphosphate: A novel multifunctional organic-inorganic hybrid flame retardant.

To achieve superior fire safety epoxy resins (EP), a novel multifunctional organic-inorganic hybrid, melamine-containing polyphosphazene wrapped ammonium polyphosphate (PZMA@APP) with rich amino groups was prepared and used as an efficient flame retardant. Thanks to the cross-linked polyphosphazene part, PZMA@APP exhibited high flame retardant efficiency and smoke suppression to the EP composites. Thermogravimetric analysis indicated that PZMA@APP significantly enhanced the thermal stability of EP composites.

Novel Melamine/o-Phthalaldehyde Covalent Organic Frameworks Nanosheets: Enhancement Flame Retardant and Mechanical Performances of Thermoplastic Polyurethanes.

Covalent organic frameworks (COFs) nanosheets prepared from condensation reaction between melamine and o-phthalaldehyde are first prepared through ball milling and then incorporated into thermoplastic polyurethanes (TPU) by solution mixing. Transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and Fourier transform infrared (FTIR) spectrometer are applied to characterize COFs nanosheets. It is observed apparently from TEM image that COFs nanosheets are obtained.

A 3D Nanostructure Based on Transition-Metal Phosphide Decorated Heteroatom-Doped Mesoporous Nanospheres Interconnected with Graphene: Synthesis and Applications.

A novel three-dimensional nanostructure based on cobalt phosphide nanoparticles (CoP NPs) and heteroatom-doped mesoporous carbon spheres interconnected with graphene (3D PZM@CoP@RGO) was facilely synthesized for the first time, and it was used for enhancing the flame retardancy and toxicity suppression of epoxy resins (EP) via a synergistic effect. Herein, the cross-linked polyphosphazene hollow spheres (PZM) were used as templates for the fabrication of 3D architecture. The 3D architecture based on CoP-decorated heteroatom-doped carbon sphere and reduced graphene oxide was prepared via a carbonization procedure followed by a hydrothermal self-assembly strategy.

Flame-retardant-wrapped polyphosphazene nanotubes: A novel strategy for enhancing the flame retardancy and smoke toxicity suppression of epoxy resins.

The structure of polyphosphazene nanotubes (PZS) is similar to that of carbon nanotubes (CNTs) before modification. For applications of CNTs in polymer composites, surface wrapping is an economically attractive route to achieve functionalized nanotubes. Based on this idea, functionalized polyphosphazene nanotubes (FR@PZS) wrapped with a cross-linked DOPO-based flame retardant (FR) were synthesized via one-step strategy and well characterized.

Studies on Synthesis of Electrochemically Exfoliated Functionalized Graphene and Polylactic Acid/Ferric Phytate Functionalized Graphene Nanocomposites as New Fire Hazard Suppression Materials.

Practical application of functionalized graphene in polymeric nanocomposites is hampered by the lack of cost-effective and eco-friendly methods for its production. Here, we reported a facile and green electrochemical approach for preparing ferric phytate functionalized graphene (f-GNS) by simultaneously utilizing biobased phytic acid as electrolyte and modifier for the first time. Due to the presence of phytic acid, electrochemical exfoliation leads to low oxidized graphene sheets (a C/O ratio of 14.

Integrated effect of supramolecular self-assembled sandwich-like melamine cyanurate/MoS hybrid sheets on reducing fire hazards of polyamide 6 composites.

A novel strategy of using supramolecular self-assembly for preparing sandwich-like melamine cyanurate/MoS sheets as the hybrid flame retardants for polyamide 6 (PA6) is reported for the first time. The introduction of MoS sheets function not only as a template to induce the formation of two-dimensional melamine cyanurate capping layers but also as a synergist to generate integrated flame-retarding effect of hybrid sheets, as well as a high-performance smoke suppressor to reduce fire hazards of PA6 materials. Once incorporating this well-designed structures (4wt%) into PA6 matrix, there resulted in a remarkable drop (40%) in the peak heat release rate and a 25% reduction in total heat release.

High-Performance Poly(ethylene oxide)/Molybdenum Disulfide Nanocomposite Films: Reinforcement of Properties Based on the Gradient Interface Effect.

Herein, the molybdenum disulfide (MoS2) was simultaneously exfoliated and noncovalently functionalized by ultrasonication in a Pluronic aqueous solution and then was used to prepare the poly(ethylene oxide) (PEO) based nanocomposite films. The homogeneous dispersion of MoS2 and strong nanosheets/matrix interfacial adhesion were confirmed by representative electron microscopes. The considerable barrier action of the effective MoS2 nanosheets obviously restricted the ordering of crystal lamellae and the motion of polymer chains and then resulted in the formation of the devastated spherocrystal structure and morphological alterations in the nanocomposites, which were confirmed by polarized optical microscopy and the high value of the glass transition temperature.