Silver-Coated\nPoly(dimethylsiloxane) Beads for Soft,\nStretchable, and Thermally Stable Conductive Elastomer Composites

Abstract

We introduce an elastomer\ncomposite filled with silver (Ag)\nflakes and Ag-coated poly­(dimethylsiloxane) (PDMS) beads that exhibits\nelectrical conductivity that is 2 orders of magnitude greater than\nthat of elastomers in which the same concentration of Ag filler is\nuniformly dispersed. In addition to the dramatic enhancement in conductivity,\nthese composites exhibit high mechanical compliance (strain limit,\n>100%) and robust thermal stability (conductivity change, <10%\nat 150 °C). The incorporation of Ag-coated PDMS beads introduces\nan effective phase segregation in which Ag flakes are confined to\nthe “grain boundaries” between the embedded beads. This\nmorphological control aids in the percolation of the Ag flakes and\nthe formation of conductive bridges between neighboring Ag shells.\nThe confinement of Ag flakes also suppresses thermal expansion and\nchanges in electrical conductivity of the percolating networks when\nthe composite is heated. We demonstrate potential applications of\nthermally stable elastic conductors in wearable devices and soft robotics\nby fabricating a highly stretchable antenna for a “smart”\nfurnace glove and a strain sensor for soft gripper operation in hot\nwater.