Silylation of layered double hydroxides via an induced hydrolysis method
Silylation of layered double hydroxides via an induced hydrolysis method
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通过诱导水解法进行层状双氢氧化物的硅烷化
DOI：
10.1039/c1jm10328h
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发表时间：
2011-01-01
影响因子：
--
通讯作者：
He, Hongping
中科院分区：
文献类型：
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作者：
Tao, Qi;Zhu, Jianxi;He, Hongping
采用诱导水解硅烷化（IHS）法、表面活性剂前驱体法、原位沉淀法和直接硅烷化法合成了一系列水滑石（LDHs）基复合材料。通过改变LDHs的制备和干燥过程中的参数，可以很容易地调节其结构、形貌、成键方式和热稳定性。表征结果表明，在乙醇介质中，干燥的LDHs与3-氨丙基三乙氧基硅烷（APS）之间不能发生直接硅烷化反应。然而，缩合反应可以在吸附的APS和LDHs板之间的加热过程中进行。当使用有和没有表面活性剂和乙醇作为溶剂的湿态衬底时，硅烷化过程可以通过APS在LDHs板表面的水解来诱导。表面活性剂在成核和结晶过程中改善了LDH的疏水性，导致蓬松形状的晶体;同时，它们占据了表面-OH位置，并留下较少的“游离-OH”可用于硅烷化反应，有利于形成具有水解的二齿（T2）和三齿（T3）键合形式的较高群体的硅烷化产物。这些键合特性导致球形聚集体和紧密键合的颗粒。所有的硅烷化产物显示出比原始LDH更高的热稳定性。
A series of layered double hydroxides (LDHs) based composites were synthesized by using an induced hydrolysis silylation (IHS) method, surfactant precursor method, in situcoprecipitation method, and direct silylation method. Their structures, morphologies, bonding modes and thermal stabilities can be readily adjusted by changing the parameters during preparation and drying processing of the LDHs. The characterization results show that the direct silylation reaction cannot occur between the dried LDHs and 3-aminopropyltriethoxysilane (APS) in an ethanol medium. However, the condensation reaction can proceed with a heating process between the adsorbed APS and LDHs plates. While using wet state substrates with and without surfactant and ethanol as the solvent, the silylation process can be induced by the hydrolysis of APS on the surface of the LDHs plates. Surfactants improve the hydrophobicity of the LDHs during the process of nucleation and crystallization, resulting in fluffy shaped crystals; meanwhile, they occupy the surface –OH positions and leave less “free –OH” available for the silylation reaction, favoring the formation of silylated products with a higher population in the hydrolyzed bidentate (T2) and tridentate (T3) bonding forms. These bonding characteristics lead to spherical aggregates and tightly bonded particles. All silylated products show higher thermal stability than those of pristine LDHs.