Inorganic-organic hybrid coatings from tea polyphenols and laponite to improve the fire safety of flexible polyurethane foams

Inorganic-organic hybrid coatings prepared via an impregnation assembly of eco-friendly materials exhibited dramatically flame-retardant properties on flexible polyurethane foam (FPUF). A nickel-complex of tea polyphenols (TP-Ni) was synthesized, and TP-Ni and laponite (LAP) were coated on the surface of FPUF. LAP/TP-Ni can be homogeneously dispersed on the surface of FPUF. Moreover, the melt-dripping phenomenon of 1LAP/4TP-Ni/FPUF was completely inhibited during the vertical flame test (UL-94) with 41.2 wt% weight gain, and it showed self-extinguished behaviors at once and passed the UL-94 V-0 rating. Additionally, the values of peak heat release rate and peak smoke production rate of 1LAP/4TP-Ni/FPUF were reduced by 71.6% and 60.9%, compared with the control. The content of gaseous toxic substances, such as CO and NCO-containing compounds, was also decreased, indicating the effect of TP-Ni/LAP on the toxicity suppression of flame-retardant FPUF. Encouragingly, the coatings deteriorated the tensile property of FPUF inconspicuously. Interestingly, the coatings do not contain traditional flame retardant elements, which offers an innovative approach for designing flame retardants. Thus, these inorganic-organic hybrid coatings show the promising potential to decrease the fire risk of FPUF.