Stable and single droplet generation is essential in drop-on-demand (DOD) inkjet printing process to deposit homogeneous and flat film. However, polymer's rheological properties and viscoelasticity can influence filament break up and droplet formation, which may lead to the formation of satellite droplets. Controlling the Z constant (related to fluid viscosity, and surface tension) and Weissenberg (Wi) number can suppress the satellite droplets and get stable and single droplet. Here, mixed solvents (chloride benzene (CB) and high viscosity cyclohexylbenzene (ChB)), different molecular weight and concentration were employed to tune the polyfluorene (PFO) viscosity, surface tension and viscoelasticity. According to the droplet ink-jetting behavior of different CB/ChB ratio, PFO molecular weight and concentration, it's found that only when the speed of the secondary droplet is faster than that of the primary droplet, a single droplet could be formed. At last, we concluded that for PFO inks 9 ≤ Z ≤ 55, Re ≥ 3 and Wi = 0.5 were adequate judgement for a stable and single droplet formation and the two factors should be controlled simultaneously to ensure a stable and single droplet.

在按需滴（DOD）喷墨打印过程中，稳定而单一的液滴生成至关重要，以沉积均匀且平坦的薄膜。但是，聚合物的流变性和粘弹性会影响长丝断裂和液滴的形成，这可能导致卫星液滴的形成。控制Z常数（与流体粘度和表面张力有关）和Weissenberg（Wi）数可以抑制卫星液滴并获得稳定的单个液滴。在这里，使用混合溶剂（氯化苯（CB）和高粘度环己基苯（ChB）），不同的分子量和浓度来调整聚芴（PFO）的粘度，表面张力和粘弹性。根据不同的CB / ChB比，PFO分子量和浓度的墨滴喷墨行为，我们发现只有当次级液滴的速度快于初级液滴的速度时，才能形成单个液滴。最后，我们得出结论，对于9≤Z≤55的PFO墨水，Re≥3和Wi = 0.5足以判断稳定和单个液滴的形成，应同时控制两个因素以确保稳定和单个液滴。