Current climate change concerns involve reconciling technological advancements with the need for sustainable solutions. The unique morphology and colloidal stability of cellulose nanocrystals (CNCs) allows for their use as an eco-friendly component in conductive inks for flexible electronics. CNCs are rod-shaped nanoparticles extracted from renewable cellulose sources and are considered emerging nanomaterials with potential applications spanning coatings, adhesives, cosmetics, food, biomedicine and energy storage devices, to name just a few. CNC and carbon nanotube (CNT) inks were formulated and printed using inkjet printing. The role of CNCs was to stabilize the CNTs and improve their “printability”. The coffee ring effect was exploited to create conductive circuits composed of grid patterns using minimal amounts of ink. Different printing substrates, substrate cleaning methods, printing temperatures, and ink concentrations were explored. The coffee ring patterns and dimensions were optimized and found to be transparent and conductive. For patterns printed at 60°C on ethanol-cleaned polyethylene terephthalate using a 1 wt.% ink composed of a 50:50 ratio of CNCs and CNTs, the rings were &lt;10 μm thick with diameters ranging from 20 to 55 μm depending on printing temperature. The sheet resistance of the printed pattern was measured to be 106 Ω/square compared to 102 Ω/square for thick films of the same ink. Optical microscopy and atomic force microscopy demonstrated the overlapping and continuous nature of the patterns and SEM confirmed that they were conductive. This work supports the future application of CNCs in flexible conductive circuits for electronic devices.

Inkjet printing of conductive nanocellulose inks for flexible electronics

2019 Spring National Meeting

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