The future of soft, conformable, and robust wearable electronics will require elastomers to provide mechanical stabilization, a soft surface to interact with human wearers, and a crucial physical barrier to protect stretchable devices from the environment. It is a difficult challenge, however, for a single elastomer to fulfill each of these needs. Here, we present a new approach that fuses a membrane of poly(dimethylsiloxane) (PDMS) onto the surface of a transparent butyl rubber (T-IIR) substrate using an organosilane-based molecular glue. The resulting membrane-interface-elastomer (MINE) structures uniquely combine the surface chemistry of PDMS with the intrinsically low gas permeability of T-IIR for the fabrication of robust stretchable devices. Our most intriguing finding, however, is that the T-IIR-PDMS interface, buried microns below the PDMS surface, exerts a remarkable influence on metal films deposited on the PDMS membrane surface from below, improving stretching and conductance performance by orders of magnitude