Dual Recyclable Polyimide-Esters from a Biobased Biimide Diacid

The biorenewable and high-performance polymers with recyclability are highly desired to establish a sustainable society. In this study, a biobased biimide diester (BD) was readily synthesized by the solvent-free imidization reaction between 1,2,3,4-butanetetracarboxylic acid (BTCA) and glycine, followed by esterification. Starting from BD and various diols, a series of polyimide-esters were successfully prepared by melt-polycondensation. The obtained polyimide-esters exhibited tunable glass transition temperatures (Tg) up to 136 °C and outstanding mechanical properties, thanks to the polar interactions between the imide rings in the BD units. Benefiting from the neighboring group participation effect and the high free volume imposed by BD units, dual closed-loop recycling was achieved: mechanical recycling without obvious compromise of thermal and mechanical properties after four cycles or chemical recycling by catalyst-free hydrolysis or methanolysis to the initial monomers in high yields. In addition, they demonstrated excellent storage stability in terms of retained chemical structures, intrinsic viscosity, and mechanical properties. This ground-up design of material synthesis opens avenues toward high-Tg and mechanically robust polyesters with dual recyclability, which are advantageous for the sustainable development of a circular economy.