High-resolution and electrically conductive three-dimensional printing of carbon nanotube-based polymer composites enabled by solution intercalation

Incorporating multi-walled carbon nanotubes (MWCNT) as conductive nanofillers is attractive for improving electrical conductivity of 3D-printed photocurable polymers. However, poor dispersion of MWCNT in the resin significantly degrades electrical conductivity and dimensional accuracy. Herein, the rational strategy for promoting dispersion employing a solution intercalation method is presented, thereby contributing to high electrical conductivity and dimensional accuracy in stereolithography process. For the mask-image-projection-based stereolithography, optimal dispersion and corresponding curing conditions (e.g., UV dose) of the MWCNT-incorporated resin were investigated with respect to various concentration. Commercial polyurethane-based resin was used as a matrix mixed with varying MWCNT concentrations of up to 0.6 wt%; an electrical conductivity of 0.071 S/m was achieved while maintaining a high dimensional accuracy verified with the International Tolerance (IT) grade. Quantitative comparison of the dimensional accuracy using standardized benchmark artifact could prove the effectiveness of the developed methods on the 3D printing quality. Complex 3D metamaterial structures and micro-to-macro sized capacitive sensors have been fabricated to demonstrate their fine quality in terms of the conductivity and physical dimension. This work can highly improve the 3D-printing qualities in the nanocomposites with high concentration fillers, thereby extending their applications to multi-functional/multi-scale structures, such as metamaterials, sensing components, and mechanical interfaces.