Electrospinning is one of the most facile and versatile techniques to prepare polymer fibers ranging from micrometers to nanometers. Although several parameters can be tuned to control the sizes and morphologies of electrospun fibers, many obstacles are still encountered as the target sizes of the fibers are getting smaller; for example, the sizes of the fibers can be effectively reduced by lowering the polymer solution concentrations but beaded or beads‐on‐string structures are usually formed. To overcome such obstacles, here a simple technique to prepare alignment‐improved and diameter‐reduced fibers without bead formation by hot‐stretching electrospun fibers at temperatures higher than the glass transition temperatures of the polymers is developed. Polystyrene and poly(methyl methacrylate) are both used in this work as model materials. The relationship between the draw ratio and diameter of the fibers is quantitatively analyzed, demonstrating the control of the fiber diameters. Moreover, higher degrees of alignment improvement at the middle part of the fibers than those at the end part is observed, which results in lower water contact angles at the middle part of the fibers. This work provides a useful post‐treatment technique to control the sizes and orientations of electrospun polymer fibers.

中文翻译：

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通过热拉伸工艺改善取向和减小直径的电纺聚合物纤维

电纺丝是制备从微米到纳米范围的聚合物纤维的最简便和通用的技术之一。尽管可以调整几个参数来控制电纺纤维的尺寸和形态，但是随着目标纤维尺寸的变小，仍然遇到许多障碍。例如，通过降低聚合物溶液的浓度可以有效地减小纤维的尺寸，但是通常会形成串珠或串珠结构。为了克服这些障碍，开发了一种简单的技术，该技术可通过在高于聚合物的玻璃化转变温度的温度下热拉伸电纺纤维来制备不产生珠子的，改善取向和直径的纤维。聚苯乙烯和聚甲基丙烯酸甲酯都用作模型材料。定量分析了拉伸比和纤维直径之间的关系，证明了纤维直径的控制。此外，观察到在纤维的中部比在端部处更高的取向度改善，这导致在纤维的中部处较低的水接触角。这项工作为控制电纺聚合物纤维的尺寸和方向提供了一种有用的后处理技术。