Nozzle Shape Guided Filler Orientation in 3D Printed Photo-curable Nanocomposites.

Here, we report guided orientation of silver nanowires (AgNWs) in extruded patterns with photo-curable 3D printing technology. A printable conductive composite material composed of polymer matrix and silver nanowires shows significantly varied electrical properties depending on the cross-sectional shape of printing nozzles: flat or circular. The composite is designed to have highly conductive AgNWs and a dielectric polymer matrix like photo-curable methacrylate resin. The dielectric permittivity of photo-curable composite resin with 1.6 vol. % of AgNWs printed through a circular nozzle showed 27. However, the same resin showed much lower permittivity with 20 when it is printed with a flat nozzle. The cross-sectional sample morphology shows that AgNWs printed with a circular nozzle are aligned, and AgNWs printed with a flat nozzle are randomly distributed. A computational simulation of paste extrusion with two different nozzle shapes showed clearly different fluidic velocities at the nozzle exit, which contributes to different fiber orientation in printed samples. A radio frequency identification sensor is fabricated with 3D printed composite using a flat nozzle for the demonstration of AgNW based 3D printed conductor.