探討非溶劑誘導巨孔電紡絲的形成機制與吸附應用

Abstract

通過在電紡絲中將非溶劑和良溶劑結合到聚合物溶液中的非溶劑誘導相分離（NIPS）方法是製造具有多孔聚合物纖維的便利方式。此方法不但創造出纖維表面上的孔洞，更使孔洞延伸至纖維的內部。靜電紡絲過程受兩個因素的影響：溶劑揮發和相分離。水蒸氣是聚合物的非溶劑，在靜電紡絲過程中也起著重要作用，其在溶劑蒸發過程中凝結並促進相分離以形成更大的孔。在本研究中，我們使用環保型聚合物 - 聚乳酸（PLA）與不同的良溶劑和非溶劑對來闡明靜電紡絲過程中巨孔纖維形成的機制。均勻的巨孔纖維只能在特定條件下獲得：首先，良溶劑必須不溶於水，非溶劑必須可溶於水，並且必須是高極性的（介電常數>35）。第二，必須選擇具有較低揮發性的良溶劑(飽和蒸汽壓在20以下)和和飽和蒸汽壓低於良溶劑的非溶劑。另外，良溶劑和非溶劑的蒸氣壓差異必須足夠大。 （蒸氣壓差須至少在6 mmHg以上） 我們使用PLA /氯苯（CB）/二甲基亞砜（DMSO）系統靜電紡絲PLA巨孔纖維，從接觸角圖中顯示出其高疏水性。在油吸附試驗中，每公克的巨孔PLA纖維可以吸附船舶廢油達到800克，並且可以有效地去除水面上的油污。此外，我們採用綠色環保的靜電紡絲技術：使用低毒性的乙酸乙酯（EA）作為良溶劑，製備具有相當的油吸附能力的PLA纖維。空氣吸附實驗表明，與光滑的高分子纖維相比，巨孔高分子纖維具有更強的捕獲懸浮粒子能力。通過使用PMMA等高極性聚合物作為電紡巨孔纖維的原料，最高可以吸附懸浮顆粒達2.5 g / g纖維。透過此方法可以輕易的選擇適合的溶劑和適當的溶液比率來電紡具有高吸附效能的巨孔纖維，以去海面油污染物和空氣中的懸浮顆粒。

Non-solvent induced phase separation (NIPS) process by combining a non-solvent and a good solvent in a polymer solution to electrospin is a convenient way to make porous polymer fibers with uniform pores extending into the interior of the fibers. The electrospun fibers are affected by two factors during electrospinning using NIPS method: solvent evaporation and phase separation. In addition, water is a non-solvent for the polymer and also plays an important role in the electrospinning process. It condenses during solvent evaporation and promotes phase separation to cause larger pores. In this study, we used an environment-friendly polymer, polylactic acid (PLA), with different pairs of good and non-solvent to clarify the formation mechanism of macroporous fibers during electrospinning. Uniform macroporous fibers can only be obtained under specific conditions: First, saturated vapor pressure of the non-solvent must be 6 mmHg lower than that of the good solvent. Second, the good solvent must be water-insoluble and the saturated vapor pressure must lower than 20 mmHg. Third, the non-solvent must be water-soluble and its dielectric constant must be higher than 35. We use PLA/chlorobenzene (CB)/dimethyl sulfoxide (DMSO) system to electrospin PLA macroporous fiber mats with a high hydrophobicity. In the oil adsorption test, the macroporous PLA fibers can effectively remove the ship waste oil on the water surface and adsorb the oil up to 800 g per gram of fibers. In addition, a green electrospinning process by using low toxicity ethyl acetate (EA) as a good solvent instead of the toxic halogenated solvents can fabricate PLA porous fibers with high oil adsorption capabilities. The smoke adsorption tests reveal that the macroporous polymer fibers are more efficient to capture the particles in the air than the smooth polymer fibers. Furthermore, the porous fibers with higher polarity, such as PMMA, show a higher efficiency of smoke adsorption up to 2.5 g/g. This work provides guidance for finding the solvents and the solution ratio for electrospinning macroporous fibers with high adsorption ability to remove oil in the leakage accidents or particles pollutants in the air.