Effect of Anion on the Formation of Mesoporous Silica and Synthesis of Metal Modified Hollow Silica Sphere

此研究工作係由三區塊兩性聚合物[聚丙烯酸甲酯-聚乙醚-聚丙烯酸甲酯，PMA-PEO-PMA] 做為模板，在酸性條件下矽酸聚合成孔洞時，探討不同鹽類水溶液環境下所展現矽膠孔洞構形的差異。在添加較高濃度不同陰離子的鉀金屬鹽類，孔徑上大小有明顯的變化：KNO3 < KBr < KCl；而在低濃度時，則可觀察到氮氣吸脫附曲線的變化：KPF6可以利於微胞二維六角結構的排列使得吸脫附曲線類似標準的SBA-15，KCl呈現的則是兩段式的脫附曲線，而KBr和KNO3無明顯變化。說明陰離子對微胞在水溶液中的形成及在矽源水解縮合的過程有其影響力。 此外，利用此高分子聚合物為模板合成出直徑介於100-400nm之空心球，其球殼具有中孔洞結構，殼層厚度為40奈米，且能擔載氧化鐵奈米粒子，同時表面積可達：378 m2/g，孔體積：0.450 cm3/g。典型過程為 APMS (3-aminopropyl trimethoxy silane)和鐵的乙醯丙酮化合物 [ Fe(acac)3 ] 溶於乙醇水溶液，滴入已加入預水解四乙氧基矽烷 (tetraethoxysilane，TEOS) 的界面活性劑水溶液，並調整其pH值，可以一步合成出含有鐵離子的空心球，經過高溫鍛燒後，形成高度分散的氧化鐵粒子，且粒徑遠小於孔徑，所以孔洞仍維持良好的通透性。利用金屬氧化物表面缺乏電子所造成的酸性性質，可以應用在Friedel-Crafts 反應，特別是對苯酚上進行第三丁基化具有良好的催化性，另外對果糖脫水反應也有很好的回收性。Using amphiphilic triblock copolymers [poly (methyl acrylate)-b- (ethylene oxide)-b- (methyl acrylate)] as templates, we have investigated the anion effect toward the porosity of mesoporous silicas. Under high concentration of potassium salts, pore diameters of the obtained silicas increases in the following order: no salt added < KNO3 < KBr < KCl. However, different hysteresis loops of the nitrogen adsorption diagrams were observed when adopting the low concentration of these salts. Different morphology of mesoporous silica with high loading of transition metal ions can be achieved by the co-condensation method. A simple co-condensation of iron(III) acetylacetone, 3-aminopropyltrimethoxysilane, and TEOS in the presence of triblock copolymers provided the mesoporous silicas in hollow spheres (MSHs) with the diameters in the range of 100-400nm, possessing uniform shell with the thickness of 35-40nm. After removal of the surfactants, iron oxide nano-particles (< 5 nm) were well-dispersed on the surface of meso-channels. Even for the higher concentration of metal ions used, the pore channels remain unblocked. The BET surface area was about 378 m2/g and the pore volume was 0.450 cm3/g