A novel technique of producing freestanding carbon nanotube films (buckypapers) using electrophoretic deposition (EPD) and post-EPD electrochemical separation (PEPDECS) is introduced. Multiwalled carbon nanotubes (CNTs) were deposited from an aqueous suspension onto stainless steel substrates using a direct current EPD procedure. Following drying and reinsertion of the electrodes into deionized water, a reversal in the direction of the current between the electrodes and an increase in the electric field facilitated an intact separation of the film from the substrate. The surface morphology was studied using scanning electron microscopy; surface groups on the CNTs on both sides of the buckypaper were identified using Fourier transform infrared spectroscopy. PEPDECS yielded films with no appreciable degradation of the surface morphology or film integrity and with mechanical properties similar to those of buckypapers produced using other assembly techniques. FTIR analysis revealed that the likely mechanism that facilitates PEPDECS for the CNTs involves the metal-catalyzed electrochemical reduction of double bonds present in surfactant molecules that coat the CNTs. This suggests the potential for wider applications involving CNT films as well as applications involving similar chemical systems.

Scalable fabrication of freestanding carbon nanotube films (buckypapers) is of notable interest in nanotechnology due to emerging, real world applications for these lightweight and flexible materials. Post-electrophoretic deposition electrochemical separation (PEPDECS), a recently developed method for the scalable production of buckypapers, involves the electrophoretic deposition (EPD) of charged carbon nanotubes onto a flat substrate in a parallel-plate capacitor configuration, followed by a reversal of the direction of the electric field to detach the film. This study explored the characteristics of the deposition and liberation of the delaminated film, such as the applied voltage and the electrode size, in search of the optimum conditions for high quality buckypaper fabrication. Bubble formation on the film, due to the electrolysis of the suspension, increased as a function of the current density. The time required to delaminate a film completely from its underlying substrate was higher at higher initial current densities. Additionally, only when the applied EPD voltage was ≥2.8 V was the integrity of the buckypaper sufficient for them to be handled. The mechanical properties of the resulting films were examined to quantify their integrity. These experiments demonstrate the dependency of successful film fabrication on variable conditions during the initial EPD and provide a means to control the properties of the final films.