Preparation of Polyurethane Nanofibers by Emulsion Electrospinning

在静电纺丝中，通常使用有机溶剂来溶解聚合物。从环境的角度出发，需要一种不使用有机溶剂的新工艺。研究了在不使用有机溶剂的情况下，采用聚氨酯预聚物/聚乙烯醇水溶液乳液进行静电纺丝的新方法。我们从PVA-aq / PU共混物中获得了直径约为2微米的PU颗粒，其中PVA从静电纺垫子中去除。通过在乳液中加入交联剂，我们观察到乳液中PU颗粒的大聚集体。用交联剂制备的乳液制得直径约260微米的PU粗纤维。交联反应在PU颗粒表面生成尿素键。我们认为聚氨酯颗粒之间的尿素键比聚集作用更强。这种聚集体通过静电纺丝工艺得到延伸，最终形成纤维。

In an electrospinning, an organic solvent is usually used to dissolve polymer. From the viewpoint of environment a new process without organic solvent is required. We investigated the novel method of electrospinning by using an emulsion of polyurethane pre-polymer / poly (vinyl alcohol) aqueous solution without using an organic solvent. We obtained PU particles about 2 micrometer in diameter from PVA-aq / PU blend, in which PVA was removed from the electrospun mat.By incorporating cross-linking agent to the emulsion, we observed large aggregates of the PU particles in emulsion. We obtained a thick fiber (about 260 micrometer in diameter) of PU by using the emulsion with cross-linking agent. The cross-linking reaction generated the urea bond on the surface of PU particles. We considered that the urea bond was more stronger than aggregating that of interaction between the PU particles. This aggregates were extended by electrospinning process and eventually led to the fiber.