Surface-Localized Chemically Modified Reduced Graphene Oxide Nanocomposites as Flexible Conductive Surfaces for Space Applications

Thermoplastic polymers are a compelling class of materialsforemerging space exploration applications due to their wide range ofmechanical properties and compatibility with a variety of processingmethods, including additive manufacturing. However, despite thesebenefits, the use of thermoplastic polymers in a set of critical spaceapplications is limited by their low electrical conductivity, whichmakes them susceptible to static charging and limits their abilityto be used as active and passive components in electronic devices,including materials for static charge dissipation, resistive heaters,and electrodynamic dust shielding devices. Herein, we explore themicrostructural evolution of electrically conductive, surface-localizednanocomposites (SLNCs) of chemically modified reduced graphene oxideand a set of thermoplastic polymers as a function of critical thermalproperties of the substrate (melting temperature for semi-crystallinematerials or glass transition temperature for amorphous materials).Selected offsets from critical substrate temperatures were used toproduce SLNCs with conductivities between 0.6-3 S/cm and surfacestructures, which ranged from particle-rich, porous surfaces to polymer-rich,non-porous surfaces. We then demonstrate the physical durability ofthese electrically conductive SLNCs to expected stress conditionsfor flexible conductive materials in lunar applications includingtension, flexion, and abrasion with lunar simulant. Small changesin resistance (R/R (0) <2) were measured under uniaxial tension up to 20% strain in high densitypolyethylene and up to 500 abrasion cycles in polysulfone, demonstratingthe applicability of these materials as active and passive flexibleconductors in exterior lunar applications. The tough, electricallyconductive SLNCs developed here could greatly expand the use of polymericmaterials in space applications, including lunar exploration, micro-and nano-satellites, and other orbital structures.