- 學位論文
有機-無機混成中空纖維膜及奈米銀複合平板膜材料之製備與性質研究
Preparation and Property Studies of Organic-Inorganic Hybrid Hollow Fiber Membranes and Nano-silver Composite Plate Membranes
摘要
中文摘要 本論文分為兩部份，一、製備奈米中空纖維膜，固定高分子基材為聚醯亞胺(PI)，添加兩種奈米添加劑 (nano-filler)，其一為片狀的黏土，其二為球狀的二氧化矽；二、製備奈米銀複合材平板膜，使用之兩種高分子基材為親水性聚乙烯醇及較疏水性聚丙烯腈，添加的奈米粒子為以光化學還原及化學還原法製備之奈米銀。這一系列所合成的有機/無機混成材料 (高分子奈米複合材料)，將進行結構及性質的分析。 第一部份，製備非對稱性聚醯亞胺 (PI) 中空纖維膜，先將PI溶於N-甲基2-四氫吡咯酮 (NMP) 紡絲液中，以插層法及溶膠凝膠法添加不同重量百分率的奈米添加劑 (包括黏土或二氧化矽)，研究主軸在探討添加劑對薄膜的結構形態、成膜機制、機械性質與分離效能的影響。 由研究結果顯示：在PI/NMP/H2O的成膜系統中，隨著增加添加黏土或二氧化矽的量，會促進中空纖維膜膜壁巨型孔洞之形成，在成膜的過程中，會促使中空纖維膜具有較厚管壁，將其應用在滲透蒸發 (pervaporation) 分離90%異丙醇水溶液時，其總通量下降但對水選擇比增加 (clay & silica ﹤1%)。添加黏土或二氧化矽會使中空纖維膜，之熱性質及機械性質方面有所提升，膜材之破壞功 (work of rupture) 亦同時增加，且聚醯亞胺奈米複合平板膜之接觸角隨著奈米添加劑劑量的增加而增加。 第二部份，將硝酸銀分別添加到聚乙烯醇 (PVA)及聚丙烯腈 (PAN)中，製備成奈米銀複合材平板膜，PVA/H2O中添加不同重量百分率的硝酸銀，使得PVA-Ag+螯合 (chelate)，經紫外線照射之後，將Ag+離子以光化學還原法還原為Ag0金屬粒子。另一方面，PAN溶於二甲基甲醯胺 (DMF) 中添加硝酸銀，直接將銀離子以化學還原法還原為Ag0金屬。這一系列奈米銀複合材經紫外線 (UV/Vis) 吸收光譜、傅立葉紅外線光譜 (FTIR)、元素分佈地圖 (SEM-mapping) 及廣角X-ray繞射 (XRD) 的鑑定可得到證實己將Ag+還原為Ag0的奈米金屬顆粒。奈米銀複合膜的表面形態，藉由掃描式電子顯微鏡 (SEM) 觀察其結構形態，結果PVA-Ag+螯合膜隨著硝酸銀的添加量的變化其表面形態產生很大的變化，然而，PVA-Ag0和PAN-Ag0的平板膜的形態是相似的，僅在複合膜材表面有金屬銀的粒子。原子力顯微鏡 (AFM) 觀察PVA-Ag0複合材表面，隨著硝酸銀的添加量使得表面變得更粗糙。但PAN-Ag0複合材表面，粗糙度反而下降。另穿透式顯微鏡 (TEM) 證實奈米複合材成功被製造；另外，利用微差掃描式熱分析儀 (DSC) 測試，結果奈米銀金屬複合材其熱性質下降，利用表面接觸角分析儀這些奈米複材皆具疏水性。在添加0.5wt%硝酸銀的量下，PVA-Ag+對大腸桿菌和金黄色葡萄球菌且具有抗菌性，但是PVA-Ag0和PAN-Ag0僅對大腸桿菌有效。
並列摘要
Abstract This dissertation divided into two parts. The preparation of polyimide nanocomposite hollow fiber includes two kinds of additive, plate clay or spherical silica, is the first part. The preparation of polyvinyl alcohol and polyacrylonitrile plate nanocomposite membrane contain silver nanoparticle is the second part. Silver nitrite converts into silver nanoparticle by using in-situ photochemical reduction and direct chemical reduction. In this research, the structure and performance of a series of organic-inorganic hybrid materials will be investigated. In the first part, casting solution contains polyimide, NMP, and nanoparticle (flat clay or spherical silica) was used to prepare asymmetric polyimide nanocomposite hollow fiber membrane. The effect of additives on the morphology, membrane formation mechanisum, mechanical properties, and pervaporation performance of the asymmetric polyimide nanocomposite hollow fiber membrane was investigated. The results revealed that the addition of nano-filler in the spinning solution and increasing the filler amount can promote the formation of macrovoids in nonocomposite hollow fiber membrane. Otherwise, the exchange rate between the solvent and nonsolvent during the membrane formation process increases resulting in an asymmetric PI hollow fiber membrane with a wider wall thickness. The material composition will affect the thermal stability, mechanical strength and the separation performance of vapor permeation of aqueous ethanol solution. The elongation at break, strength at break, and work of rupture increase with nano-filler is a unique phenomenum different than general polymer. Moreover, water contact angle increasing presents self-clearing performance. The second part, a series of nano-scale silver polymer composite films were prepared from polyvinyl alcohol silver ions chelate aqueous solution. Silver ions transfer to silver by in-situ photochemical reduction using UV-irradiation. Other way, polyacrylonitrile silver ions chelate in N,N-dimethylformamide (DMF) will change into silver by direct chemical reduction. The reduction of silver ion in nano-composite films were confirmed by UV/vis optical absorption, Fourier-transformation infrared spectroscopy (FTIR), SEM-mapping, and X-ray diffraction (XRD). The surface morphology of nano-scale silver polymer composite films were investigated by atomic force microscopy (AFM), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The amount of nano-scale silver in polymer composite films will affect the thermal stability, contact angle and antibacterial activities. In this study, we found that the structural morphology of PVA-Ag+ chelate films change vastly due to the changes in loading amount. However, silver nano-particles produced by in situ reduction UV-irradiation shown particles on the surface of PVA films. The surface morphology of PVA-Ag0 and PAN-Ag0 membrane is similar. PVA-Ag+ is effective prohibite the growth of Escherichia coli and Staphylococus aureus in 0.5 wt% silver nitrite loading. PVA-Ag0 and PAN-Ag0 films are effective in prohibiting the growth of Escherichia col. Furthermore, we demonstrated that the hybrid composite films have good hydrophobic characterization owing to the presence of nano-scale silver. From DSC experimental results, the glass transition (Tg) and melting temperatures decreases with increasing AgNO3 loading owing to destroy of the crystalline.