Programmed Curing Directs Nanophase Organization in Active Ester‐Cured Epoxies for Strong Adhesion, Toughness, and Recyclability

Advanced electronic packaging requires dielectric materials that combine reliable adhesion and dielectric performance with end‐of‐life management. Practical anhydride‐cured epoxy networks generally contain polar hydroxyls, which promote hydrogen‐bond‐mediated cohesion and adhesion but degrade dielectric performance and moisture resistance. Active‐ester curing reduces hydroxyl density, yet it can weaken adhesion by diminishing these interactions. Here, we report a strategy of programmed curing to direct nanophase organization, which exploits the different apparent curing kinetics of two active‐ester curing agents bearing dodecanoyl and furoyl termini (AE‐D and AE‐F, respectively). During stepwise heating, these kinetic differences create a structural evolution window before gelation, enabling C12‐driven nanophase formation in the bulk and enrichment of oxygen‐containing groups at metal oxide interfaces. Consequently, the optimized RE‐D50F50 network achieves an aluminum lap‐shear strength of 22.96 MPa and a tensile toughness of 25.5 MJ m −3 , while maintaining a dielectric constant of 3.39 and a dielectric loss of 0.019 at 10 MHz, along with stable performance under hygrothermal aging. Mild acid‐triggered deconstruction further enables the isolation of small‐molecule products and the recovery of encapsulated components. This work establishes programmed curing as a route to improve the adhesion and toughness of low‐dielectric active‐ester‐cured epoxies while advancing sustainable epoxy materials for electronic packaging.