本研究以10 wt.% PNIPAM水溶液做為芯部溶液，而5 wt.% PVA水溶液為鞘部溶液，利用循環水浴槽與自製玻璃套管將芯部溶液溫度控制在低溫以確保其為一相狀態，而鞘部溶液則保持在室溫(~19 oC)。在芯部與鞘部溶液均為一相狀態下進行同軸電紡絲，製備PNIPAM/PVA芯鞘型奈米纖維。固定鞘部溶液流量為0.5 mL/h，芯部流量(Qc)由0.05上升至2 mL/h，探討PNIPAM水溶液流量上升對電紡所得纖維結構、形態的影響。

利用玻片收集中段的液柱，在顯微鏡下可觀察到液柱內部存在因芯部與鞘部液體對比度不同而產生的邊界，證明液柱為芯鞘型結構。並以氦-氖雷射光源打擊電紡液柱，並沿著赤道方向掃描後方幕上收集所得距針底(z=0)不同距離處的散射圖案，發現掃描所得強度分佈圖中第一個強度最大值對應的散射向量數值(qm,1)隨z上升而往高q處移動，代表液柱直徑逐漸縮減。受限於芯鞘型液柱的複雜性，目前難以使用一關係式由qm,1快速估算液柱的內、外直徑數值。而當Qc逐漸上升時，在液柱長度一半處掃描散射圖案所得強度分佈中，qm,1往低q處移動，意味著芯鞘型液柱的直徑隨Qc上升而變大。

最後，以穿透式電子顯微鏡觀察不同Qc下電紡所得纖維內部的結構，發現均有因電子雲密度不同而產生的邊界存在，代表所得均為芯鞘型纖維。以掃描式電子顯微鏡觀察電紡纖維形態，發現當Qc=0.05 mL/h時，大部分纖維具有barb結構。隨著Qc上升，電紡纖維外觀逐漸改善為beaded-free纖維形態，代表導入芯部溶液有助於改善纖維形態。量測所得纖維外直徑(Df)與Qc間存在關係式Df~Qc0.35。

In this study, 10 wt.% PNIPAM and 5 wt.% PVA aqueous solutions were used as core- and shell- fluids in the co-axial electrospinning to prepare PNIPAM/PVA core/shell fibers. We used a circulator with cold water bath to cool down the temperature of PNIPAM solution inside the home-made glass jacket, to maintain the homogenous solution state. Air condition was used to control the room temperature to be ~19 oC, same as the temperature of PVA solution. At a fixed flow-rate of shell fluid (0.5 mL/h), the flow-rate of core fluid (Qc) was changed from 0.05 to 2 mL/h to reveal the effects of Qc on the electrospinning jet and the structure inside the as-spun fibers.
Cover glasses were used to collect the liquid jet at the middle part. From OM images, the boundary of the two different aqueous solutions could be observed, it prove that the electrospinning jet is core/shell jet. He-Ne laser beam was targeted on the core/shell jet with different Qc, and the scattering patterns on the screen behind the jet were scanned along the equator direction to obtain the intensity profiles. From the results, the magnitude of the scattering vector of the first intensity maximum (qm,1) was determined. The value of qm,1 increased with the increasing z, it means that electrospinning jet diameter became thinner. At the middle of electrospinning jet, the qm,1 moved toward the low q value, it means that diameter of core/shell jet increased with the increasing Qc.
At last, TEM was used to prove that the as-spun fiber is core/shell fibers. In the SEM images, it was found that the existence of core fluid is benefit to improve the morphology of as-spun core/shell fibers. The morphologies of core/shell fiber become beaded-free with the increasing Qc. The measured outer diameter of as-spun fiber (Df) increased with the increasing Qc.

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