Structure–fire-retardant property correlations in biodegradable polymers

Because of widespread public concern about plastic waste treatment and recycling, there is a global trend toward replacing non-biodegradable polymers with biodegradable polymers. However, the inherent flammability of most biodegradable polymers presents a significant barrier to their potential application, necessitating the rapid development of fire-retardant biodegradable polymers. Herein, three major categories of fire retardants (FRs), including intrinsic FRs, additive FRs, and fire-retardant coatings, especially widely studied additive FRs in the categories of organic, inorganic, and inorganic–organic, are reviewed, revealing how the physical and chemical structures of FRs affect the fire-retardant efficiency of biodegradable polymers and concluding the influencing factors of their fire retardance from the perspective of the physical and chemical structures of FRs. This work provides fundamental data and mechanistic analyses for the fire-retardant parameters of biodegradable polymers by integrating/adding diverse types of FRs, to provide guidance for fabricating highly efficient fire-retardant biodegradable polymer materials and inspiring the development of future research and application of functional biodegradable polymers toward circular economy and greater sustainability.