Ugi five-component polymerization of CO2 and 5-hydroxymethylfurfural derivatives toward the synthesis of functional polyfurans

Abstract

Converting CO₂ and bio-based platform chemicals into functional polymer materials is currently extremely challenging. In this work, we successfully achieved Ugi five-component polymerization (Ugi-5CP) of CO₂ and 5-hydroxymethylfurfural (HMF) derivatives to prepare functional polyfurans at room temperature, without the use of metal catalysts. Furthermore, the Ugi-5CP method was extended to various diamines and dialdehydes, producing polyfurans with satisfactory molecular weights (up to 14 400 g mol⁻¹), reasonable yields, and good solubilities. The Ugi-5CP facilitated the incorporation of functional units, including furan, amide, and urethane. Theoretical calculations confirmed the formation of intramolecular hydrogen bonding between the oxygen atom in the furan ring of the main chain and the hydrogen atom in the amide of the side group. Benefiting from the regulation of inter- and intramolecular hydrogen bonding by the furan moiety, the resulting polyfurans exhibited unique nonconventional fluorescence behavior, excellent film-forming ability, and a high strength of 12.0 MPa with an elongation at break of 366.9%. Therefore, this work not only introduces a novel strategy for copolymerization using CO₂ and bio-based platform chemicals but also provides valuable insights into the regulatory mechanism of multi-component polymerization on the properties of bio-based polymers.