Controlling the Polymer Ink’s Rheological Properties to Form Single and Stable Droplet

The formation of single and stable ink droplets is crucial for producing high-quality functional films in drop-on-demand (DOD) inkjet printing. The stability and singularity of droplet formation are significantly influenced by filament breakup behavior, governed by the rheological parameters of the ink formula. This study explores the droplet formation behavior of Poly3-hexylthiophene (P3HT) ink across various Weber numbers (We) and assesses the impact of the Z value on the formation of single ink droplets. Observations reveal that as the We number increases, droplet morphology transitions from single to double, and eventually to sputtered droplets. Results demonstrate that stable, single droplets form when the We number ≤ 13 and 12 < Z < 34, with a pulse duration of approximately 340 μs. When the We number exceeds 13, the molecular chains of P3HT stretch due to high hydrodynamic forces, resulting in the formation of unwanted satellite droplets.