Self-Cross-Linking of Amine-Functionalized Polydimethylsiloxane on Metal Substrates with Humidity-Responsive Healing

Polymer coatings require durability to maintain their protective and functional properties throughout their service life. This study presents amine-functionalized polydimethylsiloxane (PDMS) coatings that cross-link through metal substrate-catalyzed imine bond formation without additional curing agents. Amine-functionalized PDMS undergoes oxidative cross-linking on metal substrates, forming imine-linked networks with viscoelastic properties that are investigated as a function of curing time and temperature. The metal-catalyzed curing results in network formation across different metal substrates with varying cross-linking kinetics. The resulting imine cross-linked PDMS exhibits reversible viscoelastic transitions triggered by humidity, enabling the healing of surface damage. Upon exposure to elevated humidity, damaged coatings flow to close the gap, while subsequent thermal treatment restores the original modulus, demonstrating controllable healing recovery cycles. These findings establish a practical route for environmentally responsive polymer coatings with applications in protective barriers and flexible electronics, where damage repair is critical for continued functionality.