High-Yield, Environmentally-Friendly, and Sustainable Synthesis of Silver Nanowires Using Tannic Acid and Their Application in Conductive Ink Preparation: Economic Analysis and Rheological Investigation

Article High-Yield, Environmentally-Friendly, and Sustainable Synthesis of Silver Nanowires Using Tannic Acid and Their Application in Conductive Ink Preparation: Economic Analysis and Rheological Investigation Sina Kaabipour 1, Finley Neal 2, and Shohreh Hemmati 2,* 1 School of Chemical Engineering, Oklahoma State University, Stillwater, OK 74078, USA 2 School of Mathematics and Natural Sciences, The University of Southern Mississippi, Hattiesburg, MS 39406, USA * Correspondence: [email protected] Received: 25 November 2024; Revised: 15 January 2025; Accepted: 11 February 2025; Published: 20 February 2025 Abstract: Silver nanowires (AgNWs) have garnered significant attention during the past decade thanks to their applications in conductive inks used for electronic applications. The polyol process, widely used for AgNW synthesis, is known for its effectiveness in producing high aspect ratio and high yield nanowires. However, this process suffers from drawbacks such as high energy consumption and use of unsustainable reagents derived from nonrenewable resources, which makes its large-scale utilization and economic feasibility challenging. In contrast, green synthesis methods offer potential solutions by employing environmentally friendly and cost-effective approaches. In this study, we offer a high-yield (90%) approach for the inexpensive, environmentally friendly, and sustainable synthesis of AgNWs, and show that the production cost per gram of AgNWs can be reduced by 31.72% compared to the polyol process. In addition, we investigate the rheological behavior of the synthesized AgNW-based conductive ink under screen printing and direct writing conditions using flow sweep, peak hold, and frequency sweep tests. The rheological behavior of the AgNWbased conductive ink provides valuable information regarding its use for various printing applications. The conductive ink demonstrated a shear-thinning thixotropic behavior for all silver nanostructure contents (2, 5, 10, and 20 wt.%), and all temperatures (25, 30, and 40 °C). It was observed that direct writing is better suited for printing inks with low colloidal content due to its lower shear rate, whereas screen printing is more effective for high-content, high-viscosity inks because it utilizes higher shear rates. The proposed cheaper and more sustainable method can serve as a promising alternative for industrial conductive ink manufacturing for printed electronic appliances such as printed circuit boards (PCBs) and flexible transparent conductive films (TCFs).