Additive Manufacturing of Electrically Conductive Nanocomposites Filled with Carbon Nanotubes

Herein, two photopolymers containing multi-walled carbon nanotubes (MWCNTs) are newly developed to 3D print electrically conductive structures via near-visible light (405 nm) stereolithography (SL) process. A free-radical resin and a hybrid cationic/free-radical photopolymer are used as a matrix and loaded with MWCNTs. A solution mixing method is selected to obtain an optimal MWCNTs dispersion. Rheological and photo-calorimetric analyses are performed by varying filler concentrations (0.25%, 0.50%, 0.75 wt%) as well as electrical properties of the cured nanocomposites are measured. Rheological characterization indicates the free-radical resin loaded with the 0.25 wt% of MWCNTs as the most suitable material for the 3D printing of electro-active systems because it guarantees a rapid and homogenous resin recoating in the vat during the printing of two different layers due to its fluidity. The optimal printing parameters for this photocurable MWCNTs-loaded resin are found through photosensitivity and photo-calorimetric analyses. Electrically conductive structures with a conductivity value of 0.0006 S cm(-1) are successfully printed, showing the immense potential of these conductive polymeric materials in replacing other standard silicon-based materials manufactured by conventional 2D lithographic processes for the development of electronic devices and microelectromechanical systems (MEMS).