Self-assembly has attracted increasing attention as an effective strategy for the fabrication of functional micro/nanostructures. Capillary force is a significant driving force for self-assembly and has become a versatile and scalable approach to building complex geometries via micro and nanoscale patterning. Traditional patterning techniques of DNA-programming, liquid-air interfaces, and external fields are not scalable due to complex manufacturing requirements. Here, we will elaborate on 3D printing as a novel patterning technique for its rapid prototyping, cost-effectiveness, and design flexibility. This work has shown a combination of 3D printing techniques to fabricate patterns and directed-assembly for the site-specific placement of one (1D) and two (2D) dimensional nanoparticles. The microns size featured pattern substrate is 3D printed by resin curing based techniques (Stereolithographic and Continuous Liquid Projection). Then, 1D (i.e., Carbon nanofibers) and 2D (i.e., MXene) dispersion were deposited on the substrates via capillary and evaporation induced self-assembly techniques. During the evaporation-drying process, the solid-liquid-air contact line is molded by the gratings' shape, and the nanoparticle experiences various fluidic forces like drag force, capillary force, and Vader wall torque, which promotes the layer-by-layer deposition of nanoparticles. The anisotropic deposition of CNF/Epoxy and MXene/Epoxy showed direction-dependent electrical conduction and mechanical sensitivity. We will also demonstrate the assembled nanoparticle/polymer composites' application for sensing toward mechanical deformation and volatile organic compounds (VOC). Our hybrid manufacturing and the polymer template effects showed enormous potential toward composite structures for directional electrical conductivity, small tensile/flexural strain sensitivity, and a wide range of VOC sensitivity, making them suitable for a multifunctional sensor.

Directed assembly of carbon nanofiber (CNF) and MXene nanoparticles on 3D printed polymer templates

ACS Spring Meeting 2021

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