藉由靜電紡絲技術與相分離法製備多孔纖維

Abstract

本研究使用高分子苯乙烯-丙烯腈共聚物（SAN）與雙溶劑系統，在電紡過程中利用不同的相分離法，製備多樣形貌的微米級纖維，雙溶劑的選擇與比例皆會影響主導的相分離機制，進而產生表面巨孔或是內部小孔結構的電紡纖維。除了溶劑組合與溶劑比例外，高分子溶液、環境參數、加工參數也皆會影響纖維形貌，故實驗中改變參數的項目為：溶劑組合、溶劑比例、高分子濃度、環境相對濕度、進料流速、電壓及鹽類添加劑等。 實驗結果顯示，不同於以往製作表面多孔纖維大多使用良溶劑與非溶劑組合，本研究使用雙良溶劑系統，當較低沸點之不溶水溶劑及較高沸點之溶水溶劑，於特定溶劑比時，亦能製備出具表面孔洞的纖維，關鍵在選擇的較高沸點親水性溶劑與空氣中水氣的結合，水為高分子的非溶劑，當其凝結於電紡射流表面，會與親水性溶劑結合，促使相分離發生，形成更大的表面孔洞，親水性溶劑與水皆為相當重要的變數，因此我們歸納出一個新的相分離機制－親水性溶劑輔助之呼吸圖法（Hydrophilic Solvent Assitant Breath Figure, HSABF）。其中最佳溶劑組合時，能形成性質優異的表面巨孔纖維，纖維接觸角可達151°，具備超疏水的特性。在油的吸附實驗中，於高分子溶液加入少量鹽類，並調整流速所電紡的纖維，製備出直徑1 µm且表面為多孔結構的纖維，對於吸油有最好的效果，在矽油中的吸附能力可達228 g/g，較相同材料直徑3 µm無孔纖維之吸附能力高出4倍。

In this study, poly(styrene-co-acrylonitrile) (SAN) and dual solvents system was used to produce micron-sized fibers with different morphologies by different phase separation methods during electrospinning. The selection and ratio of the solvents affect the dominant phase separation mechanism, resulting in electrospun fibers with surface macroporous or internal small pore structures. In addition to solvent pair and solvent ratio, polymer solution, environmental parameters and processing parameters also affect the fiber morphology. Therefore, the following parameters were manipulated in the experiment: solvent pair, solvent ratio, polymer concentration, ambient relative humidity, feed flow rate, voltage, and salt additives. In the past, the pre-mixed polymer/good solvent/nonsolvent ternary solution was mostly used for fabricating surface porous fibers. In this study, however, we found that in the dual good solvent system, when the lower boiling point solvent is immiscible with water and the higher boiling point solvent is soluble with water, the fibers with surface pores can also be produced at specific solvent ratio. Water is a non-solvent for the polymer. The key point is that water from the surrounding air condenses on the fiber jets surface, the higher boiling point hydrophilic solvent can diffuse into the condensed water droplets to induce phase separation and cause larger surface pores. Both hydrophilic solvent and water are very important experimental variables, so we proposed a new phase separation mechanism - Hydrophilic Solvent Assistant Breath Figure (HSABF). The best solvent pair can form surface macroporous fibers with excellent properties, with the fiber contact angle reaching 151° and demonstrating superhydrophobic properties. In the oil adsorption experiment, we prepared porous fibers with 1 µm diameter, which show the best performance on oil adsorption. The adsorption capacity in silicone oil could reach 228 g/g, which was 4 times higher than the adsorption capacity of non-porous fibers with 3 µm diameter.