Organic Molecule-Modulated Phase Evolution of Inorganic Mesostructures

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• 作者：Junming Sun ; Ding Ma ; He Zhang ; Feng Jiang ; Yi Cui ; Rong Guo ; Xinhe Bao
• 刊名：Langmuir
• 出版年：2008
• 出版时间：March 18, 2008
• 年：2008
• 卷：24
• 期：6
• 页码：2372 - 2380
• 全文大小：1347K
• 年卷期：v.24,no.6(March 18, 2008)
• ISSN：1520-5827

文摘

The involvement of alkane in the P123-TEOS-NH₄F-H₃O⁺ synthesis system alters the phase behavior of thecomplex emulsion system dramatically. Changing one of the reaction parameters (such as the initial reaction temperature,IRT) will result in diverse solution mesostructures. With subsequent condensation of silicate species, interestinginorganic materials with various mesostructures are obtained. The present work is aimed at understanding the phaseevolution behavior of this complex alkane (C₆-C₁₂)-P123-TEOS-NH₄F-H₃O⁺ emulsion system, with emphasison the influence of alkane chain number (ACN) and IRT. HREM (high-resolution electron microscopy), XRD (X-raydiffraction), nitrogen sorption, FFEM (freeze-fracture electron microscope), and interfacial tension techniques havebeen used to investigate the phase behavior of the emulsion system and the structure of the inorganic products. Alinear relationship between the phase-transformation temperature (PTT) and ACN has been established, which couldbe attributed to the modification of alkane with respect to the hydrophobic-hydrophilic properties of the complexemulsion system. Moreover, the right combination of reaction temperature, ACNs, and thus-induced swelling ofhydrophobic PPO blocks as well as the modification of hydrophilicity of PEO brushes by silicate oligmers is the drivingforce in altering the packing parameter/geometry of the copolymers surfactant (P123) aggregates. This leads to thediverse structures of the obtained mesoporous silicas. A temperature-induced phase-transformation mechanism hasalso been proposed and discussed.