(171f) Bioinspired, Conductive Polymeric Composites of End-Capped Oligopeptides

Wearable electronics are a growing field of research due to their applications in health care and advanced textiles. To ensure the success of wearable electronics, the composite device should be both biocompatible and conductive, as well as flexible, stretchable, and gas permeable so that they can be worn comfortably. One route to constructing these devices to engineer a conductive polymer composite, consisting of a polymers matrix that provides mechanical support, and a conductive filler. Even though there exist many polymers and elastomers which can be used for such composites, the same cannot be said for the conductive fillers. For example, carbon nanotubes and metallic nanowires, the two most commonly employed conductive fillers, are much stiffer than the polymeric matrix and this mechanical mismatch causes the composites to fall apart upon stretching. Moreover, the use of carbon nanotubes in implantable devices leads to cytotoxicity concerns. Therefore, a novel conductive filler that is both biocompatible and flexible is needed to fabricate wearable electronics that are comfortable and durable. In this presentation, we designed composites featuring conductive nanowires formed by the self-assembly of in-house synthesized oligopeptides that serve as our conductive, biocompatible, and flexible fillers. As these oligopeptides self-assemble in aqueous media, we have chosen polymers that are water-soluble and can be easily crosslinked to serve as our matrix. We have employed voltammetry, chronoamperometry, and rheology to characterize the composites and determined the percolation threshold, i.e., the minimum concentration of conductive filler required for the composites to be electrically conductive. The effect of pH value, temperature, and molecular weight of the polymer on the conductivity of these composites has also been systematically investigated. Among these parameters, relative humidity has the most dominating effect as the conductivity increases by the four orders of magnitude when humidity increases from 30% to 90%. These biocompatible and conductive composites have the potential to advance the field of medical science, as they hold potential for use in wearable electronics, smart implants, smart drug delivery, tissue scaffolding, and many other applications.