Gigantic Stretchability of Conductive Elastomers with 3D Nanostructures

Abstract

Flexible electornics requires highly stretchable conductive components. To meet the requirement people suggest elastomers loaded with functional fillers such as carbon black, metal nanoparticles, and carbon nanotubes (CNT). Still, these methods fall short of improving conductivity of composite materials under large strain. Recently, by mechanically perforating with two-dimensional (2D) net-shaped structures, uniaxial stretchability of elastomers is increased up to 35 % from its intrinsic stretchability. The shape of 2D holes in the perforated films effectively deconcentrate tensile stratins during stretching. In this work, we demonstrate the improvement of stretchability by using three-dimensionally (3D) perforated elastomers. 3D patterned nanostructures, by using special positive-tone resists during proximity field nanopatterning (PnP), work as a template for conductive elastomers because of its easy dissolution after the infiltration of the elastomer. Through this template, thick (~10 μm), net-shaped 3D elastomers are successfully fabricated; procedures inclduing infiltration of PDMS and removal of polymer templates by water-based solution yield 3D nanostructured PDMS films. 3D PDMS shows gigantic stretchability compared to normal PDMS by effective deconcentration of tensile strains during elongation. Some basic stress-strain analysis proves the stable conductivity of elastomers after elongation. The ultimate elongation of 3D nanostructures is investigated with numericla calculations.