Crosslinking site sharing-driven interface engineering to enhance adhesion between PDMS substrates and Ag–PDMS conductors

Abstract

Elastomeric silicon polymers have gained attention as promising stretchable substrate materials owing to their outstanding chemical stability and mechanical and optical properties. However, their low surface energy and chemical inertness hinder reliable adhesion with stretchable conductors, which leads to permanent device failures. To address this issue, this study proposes an interfacial engineering strategy to enhance the adhesion between polydimethylsiloxane (PDMS) substrates and stretchable conductors via crosslinking site sharing. Using an Ag–PDMS composite as a stretchable conductor material, spontaneous crosslinking could be induced at the interface with the PDMS substrate during the thermal curing process. Moreover, tailoring the polymer chain composition of the PDMS substrate allowed the investigation of the factors influencing interfacial crosslinking and the determination of conditions favourable for enhanced adhesion. Additionally, we developed a selective surface modification technique that enhances interfacial adhesion by locally infiltrating vaporised crosslinkers into predefined conductor regions while preserving the bulk modulus of the predesigned substrate. This localised reinforcement also improves the surface modulus of the PDMS substrate at the adhesion interface, promoting effective stress dissipation during mechanical deformation. Consequently, it suppresses crack initiation and propagation in the conductor regions, offering a promising strategy for enhancing the reliability of stretchable electronic devices.