Naphthalene engineering of chemically recyclable polyesters with enhanced thermal and mechanical properties

The development of new chemically recyclable polymers is highly demanded for establishing a circular plastics economy. The superior aliphatic-aromatic 5H-1,4-benzodioxepin-3(2H)-one (BDPO) system combines the high reactivity of aliphatic esters with the beneficial properties of aromatic linkages, but its material properties remain to be further explored. Herein, we prepared a series of BDPO-based monomers (M1–M4) with methoxy, bromo, and naphthalene substituents to further tune the properties of this system. Notably, these monomers retained the high polymerizability and recyclability of the pristine BDPO system. The naphthalene engineering of BDPO contributed to a significant improvement of the glass transition temperature (T_g > 100 °C). More impressively, naphthalene engineering of the BDPO system via copolymerization could fine-tune the mechanical properties thoroughly from brittleness to ductility, delivering various mechanical properties.