Chemically Degradable Carbon Dioxide-Incorporated Polyurethane From Biomass-Derived Polyester Polyols as Sustainable Adhesives

Polyurethane (PU) adhesives are extensively employed in flexible packaging owing to their strong adhesion and excellent wettability. However, most conventional PU adhesives are petroleum-based, which has driven growing interest in biobased alternatives. In this article, we synthesized biobased PU adhesives for flexible packaging applications using 2,5-furandicarboxylic acid (FDCA) and carbon dioxide (CO₂). FDCA-based polyols (FPs) (2500–3500 g mol⁻¹) with processable viscosities were prepared from FDCA, succinic acid, and 1,3-propanediol. To further enhance adhesion by increasing hydrogen-bond density, the diol and triol containing urethane moieties were synthesized via CO₂-utilization technology. In T-peel tests, the adhesives crosslinked with CO₂-based triols exhibited the highest adhesion strength (986 gf/25 mm) and were compared with those crosslinked using petroleum-derived trimethylolpropane (TMP). The prepared adhesives exhibited low glass transition temperature (from −28 to −18°C), ensuring flexibility at room temperature. In addition, the synthesized adhesives could be degraded through base-catalyzed transesterification in ethanol/ethyl acetate, enabling clean substrate recovery. These sustainable FDCA/CO₂-based PU adhesives demonstrate strong potential as alternatives to petroleum-derived adhesives for flexible packaging.