Developing the Surface Chemistry of Transparent Butyl Rubber for Impermeable Stretchable Electronics

Abstract

Transparent butyl rubber is a new elastomer that has the potential to revolutionize stretchable electronics due to its intrinsically low gas permeability. Encapsulating organic electronic materials and devices with transparent butyl rubber protects them from problematic degradation due to oxygen and moisture, preventing premature device failure and enabling the fabrication of stretchable organic electronic devices with practical lifetimes. Here, we report a methodology to alter the surface chemistry of transparent butyl rubber to advance this material from acting as a simple device encapsulant to functioning as a substrate primed for direct device fabrication on its surface. We demonstrate a combination of plasma and chemical treatment to deposit a hydrophilic silicate layer on the transparent butyl rubber surface to create a new layered composite that combines Si-OH surface chemistry with the favorable gas-barrier properties of bulk transparent butyl rubber. We demonstrate that these surface Si-OH groups react with organosilanes to form self-assembled monolayers necessary for the deposition of electronic materials, and furthermore demonstrate the fabrication of stretchable gold wires using nanotransfer printing of gold films onto transparent butyl rubber modified with a thiol-terminated self-assembled monolayer. The surface modification of transparent butyl rubber establishes this material as an important new elastomer for stretchable electronics and opens the way to robust, stretchable devices.

Membrane-Interface-Elastomer Structures for Stretchable Electronics

“…We deposited GPTMS on the T-IIR surface by using our previously reported method, whereby a plasma oxidation step initially produces a low density of oxidized functional groups on the surface. 24 Subsequently exposing this surface to silicon tetrachloride vapor in ambient conditions deposits a thin silicate film on the surface (T-IIR/SiO 2 ), which then supports the formation of the GPTMS layer. Bringing the APTES-modified PDMS membrane into conformal contact with the GPTMS-modified T-IIR surface enables the interfacial ring-opening reaction, adhering the PDMS membrane to the surface of T-IIR to yield the PDMS-T-IIR MINE structure, which we term MINE-30 to denote the PDMS membrane thickness ( Figure S2).…”

“…We have previously shown that T-IIR undergoes destructive bond scission reactions in air or oxygen plasma, producing a low density of oxidized functional groups on the surface. 24 Creating a hydrophilic T-IIR surface requires additional chemical treatment with silicon tetrachloride vapor, which deposits a thin, hydrophilic silicate film on the surface, similar to the surface formed by the simple one-step plasma oxidation of PDMS. 12 In the present paper, we further show that PVD of metals-the routine method used to fabricate stretchable conductors on PDMS-produces discontinuous metal films on the T-IIR surface that are inoperative as stretchable conductors.…”

Triplet transport in thin films: fundamentals and applications

“…While oxygen must be eliminated to prevent quenching of triplet excitons, it may be possible to use oxygen barriers that are already commercially available, e.g. polyisobutylene, 134,135 or the barrier layers used in the commercial production of OPV cells.…”

Wearable and Washable Conductors for Active Textiles

“…44 Recently, butyl rubbers have been used as hermetic seals for stretchable electronics. 45,46 Despite its relatively low permeability, butyl rubber is still too permeable to prevent dehydration of hydrogels at the scale of a typical textile fiber; see Table 1.…”