Mussel‐Inspired, Self‐Healing, Highly Effective Fully Polymeric Fire‐Retardant Coatings Enabled by Group Synergy

Abstract Fire‐retardant coatings represent a universal cost‐effective approach to providing fire protection for various substrates without compromising substrates’ bulk properties. However, it has been attractive yet highly challenging to create waterborne polymeric fire‐retardant coatings combining high‐efficiency, generally strong adhesion, and self‐repairability due to a lack of rational design principles. Inspired by mussel's unique adhesive, self‐healing, and char‐forming mechanisms, herein, a “group synergy” design strategy is proposed to realize the combination of self‐healing, strong adhesion, and high efficiency in a fully polymeric fire‐retardant coating via multiple synergies between catechol, phosphonic, and hydroxyethyl groups. As‐created fire‐retardant coating exhibits a rapid room‐temperature self‐healing ability and strong adhesion to (non)polar substrates due to multiple dynamic non‐covalent interactions enabled by these groups. Because these functional groups enable the formation of a robust structurally intact yet slightly expanded char layer upon exposure to flame, a 200 µm‐thick such coating can make extremely flammable polystyrene foam very difficult to ignite and self‐extinguishing, which far outperforms previous strategies. Moreover, this coating can provide universal exceptional fire protection for a variety of substrates from polymer foams, and timber, to fabric and steel. This work presents a promising material design principle to create next‐generation sustainable high‐performance fire‐retardant coatings for general fire protection.