Truxillate polyesters derived from dimethoxycinnamic acid: Melt-polycondensation, properties, and hydrolytic and enzymatic degradation

We report on the synthesis and characterization of polyesters and copolyesters derived from a rigid aromatic cyclobutane diester monomer, 3,4-dimethoxytruxillic acid dimethyl ester (DMDMTr), prepared via [2+2] photodimerization of 3,4-dimethoxycinnamic acid. Using an optimized two-step melt transesterification–polycondensation method, DMDMTr was polymerized with various aliphatic diols to yield polyesters with glass transition temperatures ( T g ) ranging from 52 to 94 °C, depending on the diol structure. Copolyesters obtained by incorporating DMDMTr into poly(butylene furanoate) (PBF) showed a linear increase in T g with the DMDMTr content, and transitioned from semi-crystalline to fully amorphous materials at ∼5 mol% DMDMTr. The polyesters showed stable melt processability and formed colorless transparent films with a thermal stability up to 360 °C. Hydrolytic and enzymatic degradation studies revealed an enhanced degradability of the DMDMTr-containing polyesters compared to PBF. General sustainability aspects such as the E factor and atom economy of the monomer were also evaluated. These findings demonstrate the promise of DMDMTr as a biobased monomer for rigid high- T g polyester materials. • 3,4-Dimethoxycinnamic acid is efficiently converted into a rigid diester monomer via a [2+2] photocycloaddition • Melt-polycondensation with various diols afforded thermoplastic polyesters with M n up to 45 kg mol -1 • Polyesters are transparent and show tunable T g -s up to 94 °C and T d -s up to 366 °C • Polyesters are degradable both enzymatically and hydrolytically under mild conditions