Modesto-López Luis B, Gañán-Calvo Alfonso M
Departamento de Ingeniería Aeroespacial y Mecánica de Fluidos, ETSI, Universidad de Sevilla, Camino de los Descubrimientos S/N, 41092, Seville, Spain.
ENGREEN, Laboratory of Engineering for Energy and Environmental Sustainability, Universidad de Sevilla, 41092, Seville, Spain.
Sci Rep. 2023 Aug 3;13(1):12639. doi: 10.1038/s41598-023-39801-3.
Polymer microfibers are ubiquitous structures across virtually all technological fields. Their applications include, for instance, filter media, tissue regeneration, wound healing and dressing, and reinforcement materials. The most effective methods for fabrication of fibrous micro and nanomaterials rely on electric fields to spin a liquid jet into an ultrafine thread that rapidly dries up forming a fiber. Continuous spinning and collection leads to formation of fiber mats. Here we report a robust yet simple approach for the massive production of liquid threads, which upon acquiring electrical charges in-flight are collected downstream in the form of fibers. The entire process takes place on-line in a single step. The liquid threads are produced through the fragmentation of a polymer solution bulk due to a turbulent interaction of a gas-liquid interface in the interior of an engineered device, a so-called Flow Blurring atomizer. The particularity of this approach consists precisely in such vigorous interaction, at the micrometer scale, which triggers a bubbly motion in the interior of the device, that is a "micro-mixing". Subsequently, the threads are passed through ionized air currents, at ambient conditions, and then stretched to sub-micrometer dimensions by electric fields. Polyvinylpyrrolidone (PVP) as well as carbon nanotubes (CNTs) or graphene oxide sheets (GOSs)-containing PVP fibers, with diameters in the range 100-900 nm, were synthesized via this approach. In the cases studied herein the method was operated at liquid flow rates (i.e. production rates) of 0.2 mL/min but it could be readily increased up to a few tens of mL/min. The method requires further improvement and optimization, nevertheless it is a promising alternative for mass production of polymer fibers.
聚合物微纤维是几乎所有技术领域中普遍存在的结构。它们的应用包括，例如，过滤介质、组织再生、伤口愈合与敷料以及增强材料。制造纤维状微纳米材料最有效的方法依赖于电场将液体射流纺成超细纤维，该纤维会迅速干燥形成纤维。连续纺丝和收集会形成纤维毡。在此，我们报告一种用于大规模生产液线的稳健而简单的方法，这些液线在飞行中获得电荷后会以纤维的形式在下游被收集。整个过程在一步中在线进行。液线是通过在一个工程装置（即所谓的流动模糊雾化器）内部气液界面的湍流相互作用使聚合物溶液本体破碎而产生的。这种方法的独特之处恰恰在于这种在微米尺度上的剧烈相互作用，它会在装置内部引发气泡运动，即“微混合”。随后，这些液线在环境条件下通过电离气流，然后通过电场拉伸至亚微米尺寸。通过这种方法合成了直径在100 - 900纳米范围内的聚乙烯吡咯烷酮（PVP）以及含碳纳米管（CNT）或氧化石墨烯片（GOS）的PVP纤维。在本文所研究的案例中，该方法在0.2毫升/分钟的液体流速（即生产率）下运行，但它可以很容易地提高到几十毫升/分钟。尽管该方法需要进一步改进和优化，但它是聚合物纤维大规模生产的一种有前景的替代方法。
