MXene/chitosan nanocoating for flexible polyurethane foam towards remarkable fire hazards reductions

Area of Science:

• Materials Science
• Polymer Chemistry
• Nanotechnology

Background:

• Flexible polyurethane foam (PUF) is widely used but suffers from high flammability and smoke generation.
• Developing effective flame-retardant and smoke-suppressing coatings for PUF is crucial for safety applications.

Purpose of the Study:

• To prepare a MXene/chitosan nanocoating on flexible PUF using a layer-by-layer (LbL) approach.
• To evaluate the impact of the nanocoating on the flammability, smoke release, and char formation of PUF.

Main Methods:

• MXene (Ti3C2) ultra-thin nanosheets were synthesized via etching and exfoliation.
• PUF was coated with alternating layers of chitosan and Ti3C2 dispersion (2, 5, and 8 bilayers).
• Flammability tests (heat release rate, total heat release), smoke emission tests (total smoke release, peak smoke production rate), and gas analysis (CO, CO2) were performed.

Main Results:

• The 8-bilayer (BL) coating resulted in minimal weight gain (6.9%) on PUF.
• Significant reductions in peak heat release rate (57.2%) and total heat release (65.5%) were observed.
• Excellent smoke suppression was achieved, with total smoke release reduced by 71.1% and peak smoke production rate by 60.3%.
• CO and CO2 emissions decreased by over 68%, and char residue reached 37.2 wt.%, indicating enhanced barrier and carbonization properties.

Conclusions:

• The MXene/chitosan nanocoating effectively enhances the flame retardancy and smoke suppression of flexible PUF.
• The LbL approach provides a method to impart significant safety improvements with minimal impact on the foam's intrinsic properties.
• The hybrid nanocoating demonstrates potential for creating safer polyurethane foam materials.