Correlation between the rheology of 2D-inks precursors and the droplet size generated from a capillary nozzle in dripping regime

TL;DR

This paper investigates how the rheological properties of 2D nanomaterial dispersions influence droplet size during inkjet printing, providing correlations that can optimize printed electronics applications.

Contribution

It offers a comprehensive rheological analysis of 2D-inks with different nanomaterials and establishes a correlation between rheology and droplet size in dripping regime.

Findings

Nanoparticles do not alter shear rheology of the carrier fluid.

Elasticity introduced by ethyl cellulose affects extensional behavior.

A correlation between rheological properties and droplet size is established.

Abstract

This study provides a complete rheological characterization of 2D nanomaterial dispersions, employed as 2D-inks precursors in printed electronics. Three different 2D nanomaterials (molybdenum disulfide (MoS2), graphene, and hexagonal boron nitride(hBN)) were dispersed in a Newtonian fluid (toluene) and a viscoelastic fluid (toluene + ethyl cellulose) with different polymer concentrations. The presence of nanoparticles does not change the shear rheology of the carrier fluid. Regarding the extensional rheology, the results showed that the pinch-off phenomenon is present in all Toluene suspensions; however, the presence of the ethyl cellulose introduces elasticity in the system, even leading to the formation of beads-on-a-string, and the relaxation times of the suspensions depends on the kind of nanoparticles present in the fluid. As controlling the droplet size when dispensing 2D-inks is of paramount importance for printed electronics, as well as for many other applications, here it is presented a correlation between the rheological properties of these 2D-inks precursors and their droplet size when generated from a capillary nozzle in dripping regime.