利用溶膠-凝膠法製備奈米級SiO2顆粒： 從物性鑑定到反應製程之最適化研究

Sol-gel Preparation of Nanoscaled SiO2 Particles: from Characterization to Optimization of Reaction Parameters

林千惠(Chien-Hui Lin)

指導教授 ： 蘇昭瑾

國立臺北科技大學/工程學院/有機高分子研究所/碩士(2007年)

摘要

本論文之研究目的是期望透過回應曲面法來探討溶膠-凝膠法所製備出的二氧化矽奈米顆粒，其製程參數對粒徑大小的影響。實驗過程中，我們使用四乙基矽氧烷（Tetraethoxysilane，TEOS）作為溶膠-凝膠製程的起始物、並用氨水為鹼性觸媒，乙醇為溶劑，同時進行水解及縮合反應來形成奈米級二氧化矽顆粒。在實驗數據分析時，我們使用反應組成物含量（即起始物、觸媒、溶劑）及反應條件（即時間、溫度）作為影響粒徑大小的製程因子來進行回應曲面法的探討。接著，我們將所製備出的奈米二氧化矽顆粒，透過掃描式電子顯微鏡（SEM）來觀察其顆粒大小及表面形態；也透過動態光散射分析儀（DLS）來測量其粒徑大小分佈狀況，我們發現可製備出 100 nm 以下且大小分佈均勻之奈米顆粒；當我們透過 X-射線繞射儀（XRD）來進行結晶性質分析時，其結果顯示此種顆粒為非晶型態；也利用傅立葉轉換紅外線光譜儀（FTIR）來分析此種顆粒，由介於 800-1260 ㎝-1 波段之間的吸收光譜情形可以判斷出，在 1100 和 800 ㎝-1 的吸收峯都有 Si-O 鍵、而在 950 ㎝-1 的吸收峯則出現 Si-OH 鍵。
接著，我們開始利用回應曲面法之原理，來探討製程參數對二氧化矽粒徑大小的影響，並透過數學分析軟體來實現回應曲面之原理，藉由電腦模擬的結果（即 2D RSM 圖及 3D RSM 曲面圖）來探討製程參數對二氧化矽粒徑大小之影響。由此數據分析的結果得知，反應組成物及反應條件的改變，對二氧化矽顆粒大小及其分佈有顯著影響，尤其以氨水的濃度對粒徑的影響為最大。隨著氨水濃度的增加，二氧化矽粒徑有顯著的變大。若 TEOS 及氨水的濃度減少而反應溫度增加時，二氧化矽顆粒會隨之變小，這是因為溫度上升時，成核速率會加快，核體的數量會變多，不過此時卻反而會抑制核體的成長。故今後若要合成奈米級二氧化矽粒子，需降低 TEOS 含量及氨水的濃度，並且要選擇比較高的反應溫度。詳細變化將於論文中討論。

關鍵字

奈米二氧化矽顆粒 ； 溶膠-凝膠 ； 回應曲面法

並列摘要

This study aims to explore the correlation between the preparation conditions and the size of sol-gel synthesized nanosilica (SiO2) using response surface methodology (RSM). Experimentally the SiO2 sols were prepared by the hydrolysis and condensation of Si precursor, tetraethylorthosilicate (TEOS) in ethanol with ammonia water as the catalyst. The as-obtained nano-SiO2 particles were characterized by scanning electron microscopy (SEM) for surface morphology and particle size, Dynamic Light Scattering (DLS) for particle size distribution, X-ray diffraction (XRD) for crystal phase, and Fourier transform infrared spectroscopy (FTIR) for surface group identification. Discussion of SiO2 property focused on the sol compositions (precursor：catalyst：solvent) and reaction parameters (time、temperature) as a function of particle size and used RSM to explore the optimized condition for preparation of the SiO2 with a requisite dimension. It was found that the size of nano-particles prepared was under 100 nm with uniform size distribution. No disctinct XRD pattern indicated that the particles were all amorphous. The results from Fourier transform infrared spectroscopy (FTIR) spectra of the sol–gel silica particles showed bands arising from asymmetric stretch vibration of Si-O (1100 cm−1), asymmetric stretch vibration of Si-OH (950 cm−1), and symmetric stretch vibration of Si-O (800 cm−1). The absorption band between 800 and 1260 cm−1 has been described as a superimposition of various SiO2 peaks, while Si-OH absorption is due to the residual organic groups. Finally, from RSM analysis, through mathematical software to implement RSM principles, we used the simulated results (such 2D RSM plots and 3D RSM surface figures) to explore the correlation between the processing parameters. It was found that the size of SiO2 nano-particles and size distribution change significantly with the composition of reactants and reaction conditions. The effect of ammonia concentration was mainly on the particle size. Increasing the concentration of ammonia increased the silica particle sizes. The particle size decreases with the increase of the reaction temperature as well as the decrease of initial concentration of TEOS and NH4OH. This result indicates the equilibrium under which condition the SiO2 nano-particles become homogeneous with narrow size distribution. The cause of the phenomenna is that the growth rate of nuclear is faster at higher temperature. The amount of nuclear is more at higher temperature. But this condition will inhibit the growth of nuclear. Detailed discussion of the possible interpretation is present in the thesis.

並列關鍵字

Silica ； Sol-gel ； response surface methodology

參考文獻

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