A Sub-Micron-Thick stretchable adhesive layer for the lamination of arbitrary elastomeric substrates with enhanced adhesion stability

Abstract

Binding two separate elastomeric substrates is of great importance for the fabrication of next generation stretchable devices including epidermal electronics and soft robotics. However, it is still extremely challenging to find an adhesive to bind arbitrary elastomers with excellent adhesion strength and reliability without compromising the stretchability of the laminated elastomeric substrates. In this study, a sub-micron-thick (∼500 nm) stretchable adhesive was synthesized by using a vapor-phase deposition method. The stretchable adhesive consists of a copolymer film containing curable epoxy and hydroxyl functionalities with sufficiently low glass transition temperature (Tg) in order to render the adhesive elastomeric. Moreover, depositing the adhesive layer in vapor phase induced an interpenetrating polymer network (IPN) at the interface between the elastomeric substrate and stretchable adhesive layer, which enabled strong binding between arbitrary elastomeric substrates such as polydimethylsiloxane (PDMS), Silbione™, 3 M VHB™, and Ecoflex™, with substantially enhanced adhesion stability and high transparency. The adhesion strength was fully retained even after more than 105 times of repeated stretch-release cycles of 50% strain. The IPN-induced stretchable but ultrathin adhesive layer developed in this study will serve as a platform bonding technology for the wide range of soft matter engineering applications.