Fire-Safe Polyesters Enabled by End-Group Capturing Chemistry

Upon heating, polyesters decompose to small molecules and release flammable volatiles and toxic gases, primarily through chain scission of their ester linkages, and therefore exhibit poor fire-safety properties, thus restricting their applications. Reported herein is an end-group-capturing effect of (bis)oxazoline groups, generated from the thermal rearrangement of the N-(2-hydroxyphenyl)phthalimide (HPI) moiety which was incorporated into the polyester chain by copolymerization. These copolyesters, as a result, exhibit high efficiency in retarding decomposition by capturing the decomposed products, particularly for the carbonyl-terminated fragments, thus increasing the fire-safety properties, such as self-extinguishing, anti-dripping, and inhibiting heat release and smoke production. The successful application of this method in both semi-aromatic and aliphatic polyesters provide promising perspectives to designing versatile fire-safe polymers.