Mussel-Inspired General Interface Modification Method and Its Application in Polymer Reinforcement and as a Flame Retardant.

Inspired by the remarkable adhesion of mussels, the mimicking of natural adhesive molecules has been widely used for surface modification. In the present study, an economical and easily available biomimic material named as tannic acid-Fe (TA-Fe) was first directly used as a surface modifier, carbonization agent, smoke inhibitor, and flame-retardant synergist. Compared with the flame-retardant magnesium hydroxide (Mg(OH)), TA-Fe-modified Mg(OH) endowed polyamide 6 (PA 6) with improved mechanical performance and flame-retardant properties. The flame-retardant and smoke-suppressant properties were tested by the limiting oxygen index and cone calorimeter tests. The flame-retardation mechanism was investigated by thermogravimetric analysis, scanning electron microscopy, and X-ray photoelectron spectroscopy. The tensile strength could increase up to 90%, and the modified flame retardant was found to have higher UL-94 grade with the same dosage of flame-retardant additives. The peak heat release rate, total heat release, peak of smoke production rate, and total smoke production were significantly reduced. The synergistic effect between TA-Fe and Mg(OH) was also discussed. This study provides new insights into the direct utilization of a biomimicking adhesive molecule, TA-Fe, to realize simultaneous composite reinforcement and flame-retardant property enhancement. Meanwhile, because of the extensive synergies of flame-retardant metal oxide with iron element and the universal growth characteristics of TA-Fe, it has potential applications in the preparation of various flame-retardant polymers.