Fully Bio-Based Pressure-Sensitive Adhesives with High Adhesivity Derived from Epoxidized Soybean Oil and Rosin Acid

In this paper, as a possible alternative to conventional petroleum-based pressure-sensitive adhesives (PSAs), a fully bio-based PSA with tunable adhesivity was designed and prepared, and the structure–property relationship of the product was investigated in detail. Rosin acid with rigid tetradecahydrophenanthrene structure was first introduced into the carboxyl-terminated copolyester through Diels–Alder addition with acrylic acid and then melt polycondensation with sebacic acid and 1,2-propanediol, and finally cured with epoxidized soybean oil to prepare fully bio-based PSAs. The tetradecahydrophenanthrene structure considerably increased the rigidity and cross-linking density of the aliphatic polyester curing network, therefore significantly improved the cohesive energy of the PSA, making it a typical removable PSA. The bio-based PSAs exhibited a similar dynamic mechanical response to their petroleum-based PSA counterparts. The adhesive properties of the bio-based PSA were comprehensively investigated by the rolling ball method, vertical debonding method, and 180° peel test, showing largely improved initial tack, static shear adhesion, and peeling force after the introduction of acrylic rosin acid (ARA). The adhesive properties could be further tailored by adjusting the ARA content and the curing time of PSA. Taking these features, this bio-based PSA provides a new opportunity for preparing environmentally friendly adhesives and other polymeric materials.