Powering up nanoparticles: versatile carbon materials for engineering and medicine

Abstract

Given carbon’s unique properties and versatility,1–4 carbon nanomaterials are being used in an increasing number of engineering and medical applications. For example, when carbon nanoparticles are dispersed in matrix materials like epoxy, polyurethane, rubber, cement, or ice, they confer unique electrical and magnetic properties, unlocking a number of new and exciting applications. When such materials are placed under strain, changes in electrical resistance (piezoresistive) and magnetic properties (piezomagnetic) emerge. In an electrolyte, the materials can expand due to an applied voltage.3 An interdisciplinary research team5 is developing carbon materials for commercialization in products such as spray-on continuous sensors for structural health monitoring (SHM), smart nanocomposites that are self-sensing, nanoreinforced laminated composites (NRLCs) that are tough in shear, and carbon nanotube (CNT) electrical fibers. This article provides a summary of how these composites are being developed at our facility to form different prototypes for diverse applications. Carbon nanofibers (CNFs) are multiwall, highly graphitic, low-cost fibers6 with diameters ranging from 70 to 200 nm and lengths up to a few hundred microns: see Figure 1(a). The fiber walls sit at an angle of about 20 degrees to the fiber axis and terminate along the surface of the fiber in a zigzag form. Remarkably, a relatively small loading of CNFs in a polymer matrix material can improve its mechanical properties and affect its electrical conductivity, piezoresistive, electromagnetic shielding, and heat dissipation characteristics. As such, promising CNF Figure 1. Nanomaterials for engineering and medical applications: (a) carbon nanofibers (CNFs) produced by Applied Sciences Inc., (b) carbon nanosphere chains (CNSCs) produced by Clean Technologies Inc., and (c) an 11mm-long carbon nanotube (CNT) array produced by the University of Cincinnati.