Sustainable, Fully Biobased Triblock Copolymers with Poly(vinylcatechol) Segments for Tough Adhesives

In this study, fully biobased triblock copolymers (PVC-b-PDL-b-PVC) were synthesized using poly(vinylcatechol) (PVC) and poly(δ-decalactone) (PDL) to create sustainable, high-performance adhesives. Five copolymers with varying molecular weights and compositions were prepared by ring-opening and atom transfer radical polymerization, and the relationship between molecular structure and physical properties was studied. Atomic force microscopy and small-angle X-ray scattering revealed that microphase separation became more pronounced with increasing molecular weight. Tensile testing showed that mechanical properties depended on molecular weight and composition, with toughness reaching 16.1 ± 2.68 MJ/m3. Lap shear tests demonstrated improved adhesive strength and work of debonding with higher PVC content, reaching 1750 ± 228 kPa and 1240 ± 507 N/m. FeCl3 cross-linking further enhanced adhesion to 2000 ± 449 kPa and 1830 ± 1110 N/m. These findings highlight the importance of molecular weight and phase separation in optimizing adhesive performance, confirming the potential of biobased copolymers for sustainable adhesives.