Ewaldz Elena, Randrup Joshua, Brettmann Blair
Materials Science and Engineering, Georgia Institute of Technology, 711 Ferst Drive, Atlanta, Georgia 30332, United States.
Chemical and Biomolecular Engineering, Georgia Institute of Technology, 311 Ferst Drive, Atlanta, Georgia 30332, United States.
ACS Polym Au. 2021 Dec 28;2(2):108-117. doi: 10.1021/acspolymersau.1c00041. eCollection 2022 Apr 13.
Ultrafine fibers manufactured through electrospinning are a frontrunner for advanced fiber applications, but transitioning from potential to commercial applications for ultrafine fibers requires a better understanding of the behavior of polymer solutions in electrospinning to enable the design of more complex spinning dopes. In complex fluids, there are viscoelastic stresses and microstructural transitions that alter free surface flows. These may not be seen in shear rheology; therefore, an in-depth analysis of the extensional rheological behavior must be performed. In this work, we use dripping-onto-substrate rheometry to characterize the extensional viscosities of electrospinning dopes from four polymer solutions commonly used in electrospinning (low- and high-molecular-weight polyvinylpyrrolidone in methanol and water as well as poly(ethylene oxide) and poly(vinyl alcohol) in water). We link the electrospinnability, characterized through fiber morphology, to the extensional rheological properties for semidilute and entangled polymer solutions and show that high-surface-tension solvents require higher extensional viscosities and relaxation times to form smooth fibers and that the Deborah and Ohnesorge numbers are a promising method of determining electrospinnability. Through this tie between solvent characteristics, viscoelasticity, and electrospinnability, we will enable the design of more complex spinning dopes amenable to applications in wearable electronics, pharmaceuticals, and more.
通过静电纺丝制造的超细纤维是先进纤维应用的领跑者，但要将超细纤维从潜在应用转变为商业应用，需要更好地理解聚合物溶液在静电纺丝中的行为，以便设计更复杂的纺丝原液。在复杂流体中，存在改变自由表面流动的粘弹性应力和微观结构转变。这些在剪切流变学中可能看不到；因此，必须对拉伸流变行为进行深入分析。在这项工作中，我们使用液滴落于基底流变学方法来表征四种静电纺丝常用聚合物溶液（甲醇和水中的低分子量和高分子量聚乙烯吡咯烷酮以及水中的聚环氧乙烷和聚乙烯醇）静电纺丝原液的拉伸粘度。我们将通过纤维形态表征的可纺性与半稀溶液和缠结聚合物溶液的拉伸流变性质联系起来，表明高表面张力溶剂需要更高的拉伸粘度和松弛时间来形成光滑纤维，并且德博拉数和奥内佐格数是确定可纺性的一种有前景的方法。通过溶剂特性、粘弹性和可纺性之间的这种联系，我们将能够设计出更复杂的纺丝原液，适用于可穿戴电子产品、制药等领域的应用。
