Development of thin film adhesive for stretchable device via initiated chemical vapor deposition process

Abstract

To achieve stretchable devices, studies have been made on various functional layers such as stretchable substrates, electrodes, TFTs, and displays, but research on adhesives for integrating them into a single product is still insufficient. In this study, an adhesive for stretchable devices was developed in copolymer system using initiated chemical vapor deposition (iCVD). In order for the adhesive thin film to withstand repeated stretching, the polymer thin film must have uniformly distributed crosslinking point and a part that can be deformed by external stress. Two kinds of monomers, glycidyl methacrylate with an epoxy ring for crosslinking point and 2-hydroxyethyl acrylate, which is easily deformable at room temperature are used for the copolymer adhesive. For measuring the adhesion properties and stability, the copolymer film was homogeneously mixed in vapor phase and coated on Ecoflex, which is stretchable and biodegradable substrate. Peel strength of the stretchable thin film was almost 2 N/10mm, and it showed great mechanical (50 % strain, $10^4$ times stretching) and chemical (Saline solution, 38 $^\circ C$, 6 hour) stability. In addition, it was transparent regardless of strain. The stretchable thin film adhesive developed in this study is expected to be applied to the field of skin attachable healthcare device, e-skin, and stretchable device.