A Superior Two-Dimensional Phosphorus Flame Retardant: Few-Layer Black Phosphorus

Area of Science:

• Materials Science
• Polymer Chemistry
• Fire Safety Engineering

Background:

• Flame retardants are crucial for protecting lives and property from fires.
• Phosphorus-based flame retardants are promising alternatives to halogenated compounds due to their lower toxicity and higher efficiency.
• Two-dimensional black phosphorus is an emerging material with potential flame-retardant applications.

Purpose of the Study:

• To compare the flame-retardant performance of few-layer black phosphorus (FLBP) with traditional phosphorus flame retardants.
• To evaluate FLBP as an additive in cellulose and polyacrylonitrile model materials.
• To elucidate the mechanism behind the superior flame retardancy of FLBP.

Main Methods:

• Comparative analysis of FLBP, red phosphorus nanoparticles, and triphenyl phosphate as flame retardants.
• Testing flame-retardant efficiency in cellulose and polyacrylonitrile model systems.
• Characterization of combustion behavior using thermogravimetric analysis (TGA) and combustion enthalpy measurements.
• Analysis of char layer morphology and chemical composition.

Main Results:

• FLBP exhibited significantly superior flame-retardant efficiency in cellulose, achieving self-extinguishing properties approximately 1.8 to 4.4 times better than red phosphorus nanoparticles and triphenyl phosphate.
• Cellulose treated with FLBP formed a more continuous and smoother char layer, with increased residue amounts (10-14 wt%) compared to other additives.
• FLBP showed a lower combustion enthalpy change (-127.1 kJ mol⁻¹) compared to red phosphorus nanoparticles (-381.3 kJ mol⁻¹).

Conclusions:

• Few-layer black phosphorus demonstrates exceptional flame-retardant capabilities, particularly in cellulose-based materials.
• The superior performance of FLBP is attributed to its two-dimensional structure and inherent thermal properties, which effectively suppress combustion reactions.
• FLBP represents a highly promising next-generation flame retardant with potential for widespread application in fire safety.