區塊共聚合物之自組裝行為研究

Abstract

論文摘要 兩性區塊共聚高分子(Amphiphilic block copolymer)，如P123或F127，可溶於水中形成微胞，微胞經矽酸鹽分子固定化後即可形成具有孔洞規則性排列之氧化矽中孔洞材料。P123由EO20PO70EO20所組成之ABA區塊共聚高分子，PEO部份為親水性之區塊，PPO部分為親油性(疏水性)之區塊，PPO聚集成微胞的內部，PEO分佈於微胞表層與水分子或矽酸鹽分子形成氫鍵鍵結。當矽酸鹽分子固化後，P123與氧化矽形成有機－無機複合孔洞材料，因PEO的特性，形成之SBA-15中孔洞材料鍛燒後會於孔洞材料之孔壁上形成微孔。利用酸矽比(proton silicon ratio, H＋/Si ratio, PSR)與溫度控制SBA-15中孔洞材料中所形成之微孔含量與微孔形態，並以低角度粉末X光繞射儀(PXRD)、氮氣吸附－脫附儀(N2 adsorption-desorption)、熱重分析儀(TGA)、矽固態核磁譜儀(Si solid-state NMR)、氙核磁譜儀(Xe NMR)與高解析度穿透式顯微鏡(HRTEM)分析SBA-15材料中微孔的含量與微孔存在於孔壁上之形態。當PSR值小於1.03時，微胞之PPO與PEO共同形成SBA-15材料之中孔洞的內徑且無微孔產生，隨著PSR值增加， SBA-15材料之中孔洞的內徑會隨之縮小且微孔含量會隨之增加；當PSR值為1.05時，微胞之PPO會形成SBA-15材料之中孔洞的內徑且微孔含量達最高，隨著PSR值持續增加，SBA-15材料之中孔洞的內徑維持不變但微孔含量卻反向減少。溫度對於SBA-15材料的中孔洞內徑與微孔含量之效應卻與PSR值相反。 本實驗室已成功發展三界面活性劑系統(CTAB+SDS+P123)於水溶液中合成具有垂直奈米孔洞之SBA-15薄板。基於應用性的廣度，將三界面活性劑系統拓展至基板表面形成薄膜材料。將覆蓋100奈米氧化矽之矽基板修飾成帶正電荷之銨離子表面，利用此帶正電荷之表面，可成功將水溶液中之三界面活性劑系統吸附於矽基板表面。當矽源注入三界面活性劑所形成之模板時，即可縮合固化形成具有垂直基板之奈米孔洞的SBA-15薄膜。 利用ATRP與NMRP活性聚合之方法合成具有炔基之聚苯乙烯-b-聚苯乙烯衍生物AB區塊共聚合物，控制其分子量分佈(Mw/Mn)小於1.2。具炔基之苯乙烯衍生物(TMSESt)單體證實可以ATRP進行活性聚合，且MPESt單體在溫和的條件控制下證實可以NMRP進行活性聚合。AB區塊共聚合物(PS16-b-PMPES8， PS16-b-PEBES8，PS63-b-PMPES20與PS163-b-PMPES29)中，其聚苯乙烯-b-聚苯乙烯衍生物區塊共聚合物會產生相分離之自組裝行為。

Abstract Hexagonal ordered mesoporous silica materials SBA-15 were synthesized using triblock copolymers and tetraethoxysilane by Zhao et al, but the high cost of silicon alkoxides was undesired features of preparative chemistry. Sodium silicate is a good candidate to replace the silicon alkoxides as the silica source. Mesoporous silica materials with tunable microporosity were synthesized starting from sodium silicate solutions and a triblock copolymer surfactant Pluronic 123 (EO20PO70EO20, Mav = 5800). The ratio of microporous volume (Vmp) of porous volume (VP) in SBA-15 can be tailored by the choice of stirring temperature and the H+/Si molar ratio (PSR) controlled the pH of reaction system. SBA-15 materials with different PSR were synthesized at stirring temperatures between 30 and 50 ℃. At 30 ℃, materials synthesized with a PSR of 1.03 proved to have a bigger pore size than materials synthesized with higher PSR resulting in SBA-15 with a larger micropore volume. The PSR and the stirring temperatures proved to play an important role in the material formed. This study focuses on a thourough investigation of PSR and the stirring temperature on the material characteristics using powder X-ray diffraction (XRD), nitrogen adsorption-desorption isotherm, thermogravimetric analysis (TGA), 29Si solid-state NMR, 129Xe NMR, and TEM. Our laboratory developed ternary surfactants systems (CTAB-SDS-P123) to construct SBA-15 silica platelets with perpendicular-nanochannels. Ionic surfactants, CTAB and SDS, would alternately array to form bilayer structure then create a lamellar confined space. Nonionic surfactant, P123, would be inserted into the lamellar confined space and formed hexagonal ordered array. In this report, we transferred the ternary surfactants systems onto the wafer surface via modification of positive charge. SBA-15 silica thin films with perpendicular-nanochannels were formed as the addition of sodium silicate solution with the pH value adjusted to between 5 and 6. The physical properties of these materials were characterized using powder X-ray diffraction (XRD) and SEM. Atom transfer radical polymerization (ATRP) of the alkyne-functional monomer 4-(trimethylsilylethynyl)styrene allowed to preparation of block copolymers with narrow molecular weight distributions (1.28). After removing TMS, the ethyne-functional copolymer could be coupled with aryl iodide. Nitroxide-mediated radical polymerization (NMRP) of the alkyne-functional monomer 4-((4-methoxyphenyl)ethynyl)styrene allowed the preparation of block copolymers with narrow molecular weight distributions (1.15). At higher conversions, side reactions, including addition of mediating nitroxides to alkyne groups, led to broader molecular weight distributions. While poly((4-(4-methoxyphenyl)ethynyl)styrene) blocks of moderate molecular weight had a fair degree of miscibility with polystyrene, the pendant alkyne groups of these copolymers led to microphase-segregated materials.