Rapidly Deformable Vitrimer Epoxy System with Supreme Stress‐Relaxation Capabilities via Coordination of Solvate Ionic Liquids
Jaeho Shin, Mo‐Beom Yi, Tae‐Hyung Lee, Hyun‐Joong Kim
Abstract
Abstract Vitrimer epoxy, capable of stress‐relaxation, has gathered attention for its ability to counter the brittleness and rigidity of thermosets. However, to date, only two strategies are proposed to address the high enthalpic barrier of a dynamic exchange reaction using high dosages of external catalysts or niche moieties as internal catalysts. Herein, solvate ionic liquids (SILs) are incorporated into commercial epoxy‐based vinylogous urethane (VU) vitrimers. During curing, the SILs facilitate epoxy ring‐opening and amine‐addition reactions, significantly reducing gel times. Furthermore, after network formation, the SILs accelerate transamination reaction within the VU networks at a dosage of only 0.5–2 mol%. This can be attributed to their high miscibilities and Lewis acidic characters, which significantly reduce the activation energy of transamination (24 kJ mol −1 ) in the SIL‐incorporated vitrimer. Thus, a high‐performing vitrimer epoxy is prepared, featuring a glassy modulus (>10 9 Pa) at room temperature and an extremely short stress‐relaxation time (≈19 s) at 160 °C. Moreover, a soft encapsulation approach is demonstrated using the vitrimer epoxy, proving the possibility of a simultaneous deformable (bent) encapsulation, reduced warpage of a flexible printed circuit board, and selective removal of encapsulants.