Intumescent multilayer nanocoating, made with renewable polyelectrolytes, for flame-retardant cotton

Area of Science:

• Materials Science
• Polymer Chemistry
• Textile Engineering

Background:

• Traditional flame retardants pose environmental and health risks.
• Developing sustainable and effective flame-retardant treatments for textiles is crucial.

Purpose of the Study:

• To create a fully renewable and environmentally benign flame-retardant nanocoating for cotton fabric.
• To investigate the effect of pH on the composition and flame-retardant performance of chitosan-phytic acid (CH-PA) coatings.
• To evaluate the efficacy of CH-PA nanocoatings using vertical flame tests and microcombustion calorimetry.

Main Methods:

• Layer-by-layer (LbL) assembly of cationic chitosan (CH) and anionic phytic acid (PA) onto cotton fabric.
• Modification of coating composition by altering the pH of deposition solutions (pH 6 and pH 4).
• Evaluation of flame retardancy using vertical flame testing and microcombustion calorimetry to measure peak heat release rate (pkHRR) and total heat release.

Main Results:

• CH-PA nanocoatings significantly reduced fabric flammability compared to uncoated cotton.
• Fabrics coated with high phytic acid (PA) content multilayers (pH 4) completely extinguished flames.
• Microcombustion calorimetry showed a reduction in peak heat release rate (pkHRR) by at least 50% for all coated fabrics, with the pH 4 coating achieving 60% reduction.
• The pH 4 coating also demonstrated a 76% reduction in total heat release, attributed to high phosphorus content enhancing intumescent behavior.

Conclusions:

• A completely renewable intumescent layer-by-layer (LbL) assembly was successfully developed for cotton fabric.
• The CH-PA nanocoatings provide an effective and environmentally benign alternative to conventional flame retardant treatments.
• The study highlights the potential of renewable materials in creating high-performance flame-retardant textiles.