Multifunctional Single Component Epoxy System and MXene/Epoxy Composite with Polymeric Imidazole Latent Curing Agent

A single-component epoxy system is necessary for industrial applications because of the convenience, productivity, and cost. Thus, there is a need for a latent curing agent that secures storage stability, while simultaneously triggering an immediate curing reaction above a certain temperature. Herein, we synthesize copolymers consisted of imidazole and furan groups in different ratios using controlled radical polymerization. Then, a microbead-type latent curing agent for epoxy resin is fabricated in an oil-in-water emulsion followed by Diels-Alder (DA) reaction between furan groups of copolymer and maleimide groups of bismaleimide (BMI) molecule at 40 °C. Compared to bare imidazole, the fabricated microbeads are able to effectively suppress reactivity due to the simultaneous operation of chemical modification and physical protection effect by DA network for 3 months at 60 °C. In addition, compared to epoxies made with imidazole, flame retardancy is secured by blocking heat and oxygen due to the high char residue formed by polymerization of BMI. Also, the increase in stiffness of specimen due to the rigid segment in the DA network results in the improvement of tensile, shear and impact strength. Lastly, as a proof-of-concept application, we incorporate fuctionalized-Ti₃C₂T_x MXene into epoxy to fabricate composite since MXene has received much consideration as a filler in polymer systems due to its remarkable electrical, electromagnetic interference shielding and flame-retardant properties. This proof-of-concept study demonstrate that MXene successfully endows the developed composites with high electrical conductivity and electromagnetic interference shielding and flame-retardant properties.