Structure of hexagonal boron nitride (h-BN) is similar to that of graphite before functionalization and exfoliation.

Functionalized reduced graphene oxide (FRGO) wrapped with a phosphorus and nitrogen-containing flame retardant (FR) was successfully prepared via a simple one-pot method and well characterized.

Similar to graphene, few‐layer black phosphorus (BP) features thermal stability, mechanical properties, and characteristic dimension effects, which has potential as a new member of nanofillers for fabricating polymer nanocomposites. Herein, a cross‐linked polyphosphazene‐functionalized BP (BP‐PZN) is developed with abundant –NH2 groups via a one‐pot polycondensation of 4,4′‐diaminodiphenyl ether and hexachlorocyclotriphosphazene on the surface of BP nanosheets. Whereafter, the resulting BP‐PZN is incorporated into epoxy resin (EP) to study the flame‐retardant property and smoke suppression performance. Cone results show that the introduction of 2 wt% BP‐PZN distinctly improves the flame‐retardant property of EP, for instance, 59.4% decrease in peak heat release rate and 63.6% reduction in total heat release. The diffusion of pyrolysis products from EP during combustion is obviously suppressed after incorporating the BP‐PZN nanosheets. Meanwhile, the EP/BP‐PZN nanocomposites exhibit air stability after exposure to ambient conditions for four months. The air stability of the BP nanosheets in EP matrix is assigned to surface wrapping by PZN and embedded in the polymer matrix as dual protection. As a new member of the 2D nanomaterials, BP nanosheets have potential to be a new choice for fabricating high‐performance nanocomposites.

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Co-based metal-organic framework (Co-MOF) nanosheets were successfully synthesized by the organic ligands with Schiff base structure. The laminated structure gives Co-MOF nanosheets a great advantage in the application in the flame retardant field. Meanwhile, -C═N- from Schiff base potentially provides active sites for further modification. In this work, 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) was used to modify Co-MOF (DOPO@Co-MOF) to further enhance its flame retardant efficiency. It is attractive that DOPO has a synergistic effect with Co-MOF on improving fire safety of poly(lactic acid) (PLA). The obvious decrease in the values of peak heat release (27%), peak smoke production (56%), and total CO yield (20%) confirmed the enhanced fire safety of PLA composites. The possible flame retardant mechanism was proposed based on characterization results. Moreover, the addition of DOPO@Co-MOF had a positive influence on the mechanical performance, including tensile properties and impact resistance. This work designed and synthesized two-dimensional MOFs with active groups. As-prepared Co-MOF with expected structure shows a novel direction of preparing MOFs for flame retardant application.

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A novel polyphosphazene (PZS) microsphere@molybdenum disulfide nanoflower (MoS) hierarchical hybrid architecture was first synthesized and applied for enhancing the mechanical performance and flame retardancy of epoxy (EP) resin via a cooperative effect. Herein, using PZS microsphere as the template, a layer of MoS nanoflowers were anchored to PZS spheres via a hydrothermal strategy. The well-designed PZS@MoS exhibits excellent fire retardancy and a reinforcing effect. The obtained PZS@MoS significantly enhanced the flame-retardant performance of EP composites, which can be proved by thermogravimetric and cone calorimeter results. For instance, the incorporation of 3 wt % PZS@MoS brought about a 41.3% maximum reduction in the peak heat-release rate and decreased by 30.3% maximum in the total heat release, accompanying the higher graphitized char layer. With regard to mechanical property, the storage modulus of EP/PZS@MoS3.0 in the glassy state was dramatically increased to 22.4 GPa in comparison with that of pure EP (11.15 GPa). It is sensible to know that the improved flame-retardant performance for EP composites is primarily assigned to a physical barrier effect of the MoS nanoflowers and the polyphosphazene structure has an positive impact on promoting char formation in the condensed phase.