Long-Range, Entangled Carbon Nanotube Networks in Polycarbonate

A method is presented for dispersing ropes or bundles of single‐walled carbon nanotubes (RCNTs) in a polycarbonate (PC) matrix. Films of PC/RCNT composites are produced, with thicknesses ranging from 10 to 60 μm, and containing small concentrations (0.06–0.25 wt.‐%) of RCNT. Our process is based on a unique method of hot casting, annealing, and drying from dichlorobenzene solution. A wet annealing prior to complete drying yields a uniform and transparent film. Despite the low RCNT loading, scanning electron microscopy (SEM) analysis of the films after fracture reveals that the RCNTs form an entangled network throughout the film, which is a key requirement for enhanced properties. An increase of up to 30 % in the Young's modulus, as compared to PC, results with this method of composite fabrication. The natural entanglement properties of carbon nanotubes (CNTs) enable the formation of a widespread network of CNTs (see Figure) within a polycarbonate matrix using simple solution mixing. The Young's modulus of this uniformly transparent binary composite is shown to reach a maximum at a CNT concentration approaching the theoretically estimated percolation limit. (See also cover.)