No abstract

No 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 premodifications 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.

Structural adhesion at high temperature has been a challenge for organic adhesives, and the commercially available adhesives that can work at a temperature above 150 °C is rather limited. Herein, two novel polymers were designed and synthesized via facile strategy, which involves polymerization between melamine (M) and M–Xylylenediamine (X), as well as copolymerization of MX and urea (U). With well-balanced rigid-flexible structures, the obtained MX and MXU resins were proved to be outstanding structural adhesives at a wide range temperature of −196~200 °C. They provided room-temperature bonding strength of 13~27 MPa for various substrates, steel bonding strength of 17~18 MPa at cryogenic temperature (−196 °C), and 15~17 MPa at 150 °C. Remarkably, high bonding strength of 10~11 MPa was retained even at 200 °C. Such superior performances were attributed to a high content of aromatic units, which leads to high glass transition temperature (Tg) up to ~179 °C, as well as the structural flexibility endowed by the dispersed rotatable methylene linkages.