Design, Performance, and Mode of Action of Hyperbranched Fire Retardants: Advancement and Perspective

The fire hazard of polymers presents a remarkable threat to life and property. In response to this challenge, the pursuit of highly efficient and reliable flame retardants is of paramount significance. Hyperbranched oligomers/polymers, featuring specific and tailorable molecular architectures, demonstrate an intensive potential in imparting diverse polymer matrices with flame retardancy and other functionalities via flame-retardant-targeted structural design. Recently, numerous studies have reported the design and application of hyperbranched flame-retardant molecules, yet a progress-relevant comprehensive summary of the molecule design, fire properties, and mode of action of hyperbranched fire retardants is still lacking. In this case, this review summarizes the state-of-the-art research progress of hyperbranched fire-retardant molecules or structures, concentrating on revealing the highly efficient design principle, structure–property relationship, and multifunctional reinforcement fundamentals. The review proceeds from various flame-retardant structural units such as phosphorus-containing, phosphorus–nitrogen bond-containing borates, silicates, and triazines, accompanied by their synthesis routes, behavior, and flame-retardant mode of action in polymers. Also, the enhancement of multifunctionality such as heat resistance, transparency, and processability is specified. The review provides comprehensive guidance for a rational design of hyperbranched flame-retardant fire-fighting molecules with high efficiency, reliability, and multifunctionality.