Versatile Epoxidized Soybean Oil-Based Resin with Excellent Adhesion and Film-Forming Property

Abstract

Deriving environmentally friendly and renewable polymers from epoxidized plant oils (EPOs) is one of the promising strategies for realizing the sustainable development of materials industry. Direct crosslinking EPOs without pre-modifications is a straightforward, efficient, and cost-effective way for the utilization of EPOs. Herein, a facile and green strategy that crosslinks epoxidized soybean oil with highly branched and flexible polyamine via ring-opening and amidation polymerizations successfully produced a novel resin with exceptional properties and versatile potential applications. After completely cured, the resin appeared to be super strong structural adhesive as it provided a room-temperature bonding strength of 12–24 MPa for metal and non-metal substrates, as well as a steel bonding strength of 11.6 MPa at cryogenic temperature (−196 °C), which is far superior to the previously reported oil-based adhesives. Meanwhile, the resin exhibited excellent film-forming ability. Particularly, by controlling the curing temperature, the films with tunable mechanical properties were obtained with a tensile strength of 3–40 MPa and an elongation at break of 17–230%. The features of uncured resin, including liquid viscoelasticity, good wettability, and high molecular weight, make it a qualified pressure-sensitive adhesive which demonstrated satisfied peel strength for various substrates.