Highly stretchable, transparent, and colorless electrodes from a diblock copolymer electrolyte

Abstract

Herein, highly stretchable, transparent, and colorless, electrodes free of liquid and non-volatile components were fabricated for the first time. Crosslinkable diblock copolymers of poly[(ethylene glycol)₉ methyl ether acrylate-b-n-butyl acrylate] with preset molecular weights and compositions were synthesized via reversible addition–fragmentation chain transfer polymerization in solution. The electrodes were made of diblock copolymer/LiClO₄ composites. It was found that the dielectric elastomer actuators (DEAs) made of an acrylic dielectric elastomer (VHB^TM4910) and the electrodes of the crosslinked poly[(ethylene glycol)₉ methyl ether acrylate₁₄₀-b-n-butyl acrylate₈₀]/LiClO₄ could exhibit actuation area strains over 100% when driven by voltage. The DEAs showed over 90% light transmittance in the entire range of the visible wavelengths. The block architecture and composition were crucial for the electrode performance although only the block of poly[(ethylene glycol)₉ methyl ether acrylate] contributed to ionic conductivity. The presence of poly(butyl acrylate) blocks avoided dewetting during electrode fabrication such that a transparent electrode was achieved.