A Ternary Bio-Based Monomer toward the Polyesters with High UV Shielding and Water-Degradation Properties

Developing renewable monomers for preparing polyesters with high UV shielding and hydrolytic degradability is a challenging topic. Herein, a ternary cyclic monomer (denoted as FBPC) containing one furan and two pyrrolidones was prepared by an aza-Michael addition reaction using biobased furan diamine and dimethyl itaconate (DMI). FBPC was melt polymerized with various diols to prepare homopolyesters with a number-average molecular mass (M_n) in the range of 22.4–30.3 kDa. The homopolyesters based on FBPC presented excellent UV shielding properties, with a maximum shielding cutoff of 398 nm, which is significantly superior to monofuran-based polyesters, such as poly(ethylene furanoate) (PEF) and poly(methyl 5-[(2-hydroxyethyl)-sulfanyl]furan-2-carboxylate) (pMSF). The hydrophilic pyrrolidone rings in FBPC enhance the hydrolytic sensitivity of the homopolyesters, giving them complete degradation within 130 days. Then, FBPC was copolymerized with poly(butylene terephthalate) (PBT) to prepare a series of copolyesters with M_n of 23.9–42.7 kDa. The UV shielding and hydrolytic degradation of PBT were significantly improved by adding a ternary cyclic monomer. In addition, FBPC was effective in toughening PBT without changing the thermal stability, and the toughness effect far exceeded those of other sugar-derived cyclic monomers. The mechanical, UV shielding, and hydrolytic degradation properties of the copolyesters can be adjusted depending on FBPC content. Overall, FBPC is an effective biobased precursor that can offer new solutions for improving polyester properties, including UV shielding and hydrolytic degradation.