具有垂直性孔道的薄片狀SBA-15的形成機制研究

Abstract

利用三界面活性界面活性劑C16TMAB/SDS/P123(十六烷基三甲基銨/十二烷基磺酸鈉/三區塊共聚高分子Pluronic 123)做為模版，與矽酸鈉共組裝形成具有開放式、垂直性奈米孔道的薄片狀SBA-15(簡稱SBA(⊥))，本研究主題為探討SBA(⊥)的形成機制，目的在於協助SBA(⊥)的開發與應用。 本研究藉由穿隧式與掃描式電子顯微鏡(TEM、SEM)、氮氣吸脫附等溫儀(N2 sorption isotherm)、熱重分析儀(TGA)、動態光散射(DLS)、以及同步輻射研究中心的粉末式X-ray繞射儀(BL 17A, powder XRD)與小角散射儀(BL23A, SAXS)的鑑定探討SBA(⊥)的形成機制。本文分為七章節，緒論、實驗、結果與討論四章、和結論。 第一部分，改變材料合成條件(SDS/C16TMAB莫耳比例、溫度、pH值)，鑑定材料的型態與孔洞結構，歸納SBA(⊥)的形成趨勢(孔道方向性、片狀厚度、孔道壁厚)與溫度、pH值的相互關聯性，並提出一個囊泡式限制空間效應的模型(氧化矽沈積囊泡)來解釋SBA(⊥)的形成，最佳 SBA(⊥) 合成條件是SDS/C16TMAB=1.5, 溫度大於40oC，pH值在3-6範圍之間；第二部分，研究C16TMAB/SDS/P123的微胞行為，探討此模版對於SBA(⊥)的片狀型態與開放式、垂直性奈米孔道的影響；第三部分，研究C16TMAB/SDS/P123/silicates的共組裝行為，考察隨時間變化的形態與結構；第四部分，藉由SBA(⊥)的特徵圖案，旋轉型與位移型莫爾條紋、區域邊界和截面結構，了解片狀SBA(⊥)間方向性結合的組裝行為。 根據研究上述結果， C16TMAB/SDS/P123形成的特殊盤狀囊泡型微胞模版促使SBA(⊥)的薄片狀型態和開放式孔洞特徵，在後期形成的囊泡式限制空間，可有效引導垂直性奈米孔道的構成。

A ternary surfactant system C16TMAB/SDS/P123 was empolyed to template the condensation of sodium silicates for SBA(⊥) formation. The study on the formation mechanism is helpful to control direct it for application. SBA(⊥) is characterized as thin sheet with 2D hexagonally arrayed perpendicular nanochannels with open-ends. We have investigated the formation mechanism by using TEM, SEM, N2 sortion isotherm, powder XRD (X-ray Diffraction), TGA (Thermogravimetric Analysis), DLS (Dynamic Light Scattering), and SAXS (solution SAXS and in-situ SAXS). This studies is organized as four section. In SectionⅠ, we have summarized the results and correlate channel orientation, sheet thickness, and wall thickness to pH and temperature by proposing a vesicle confinement effect. The best recipe for SBA(⊥) synthesis is SDS/C16TMAB=1.5, T≧40oC. In SectionⅡ, the self-assembly process of C16TMAB/SDS/P123 reveals the correlation between the appearance of disk micelles and the silica sheet formation. In SectionⅢ, the co-assembly process of surfactant/silicate hybrids has been investigated. In SectionⅣ, it is found that the assembly behaviors in the late stage of SBA(⊥) formation follow the oriented attachment mechanism. It is confirmed that the sheet form and the perpendicular nanochannels of SBA(⊥) should derive from disk micelle template.