gamma-APTES modified silica gels: The structure of the surface layer
gamma-APTES modified silica gels: The structure of the surface layer
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DOI：
10.1006/jcis.1996.0241
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发表时间：
1996-05-10
影响因子：
9.9
通讯作者：
Zhmud, BV
中科院分区：
文献类型：
--
作者：
Golub, AA;Zubenko, AI;Zhmud, BV
利用分子力学的MM2方法和量子化学的AM1方法（在簇近似中），研究了γ - aptes修饰二氧化硅表面的各种化学结构，以及该表面氨基和其他极性基团之间是否存在氢键。只有在少数情况下，几何因素似乎对氢键有利。氨基和残余硅烷醇之间的氢键可以在表面上伸展的氨基丙基尾部产生，或者在硅烷球偶联的地方。相邻氨基之间的氢键是通过锚定硅烷醇的烧结实现的，这使得氨基靠近在一起。无定形二氧化硅表面的分子粗糙度促进了氢键的形成，在吸附水的情况下，质子从硅醇向氨基转移，特别是在与水环境接触时，表面具有宏观两性离子的特征，电荷滴定实验证实了这一结论。在处理电荷滴定的实验数据时，考虑到了二氧化硅的溶解度。(C) 1996学术出版社，Inc.
Making use of the MM2 method of molecular mechanics and the AM1 method of quantum chemistry (in the cluster approximation), various chemical structures at the surface of gamma-APTES-modified silicas have been examined with respect to the existence of hydrogen bonding between amino groups and other polar groups at that surface. Only in few cases the geometrical factors appear to be auspicious for hydrogen bonding. Hydrogen bonds between amino groups and residual silanols can arise for sprawling aminopropyl tails on the surface, or in places of coupling of silica globules, Hydrogen bonds between neighboring aminogroups are enabled by the sintering of anchor silanols, which makes the amino groups come close together. Hydrogen bonding is facilitated by the molecular roughness of the amorphous silica surface, In the presence of adsorbed water, which promotes the transferring of protons from silanols to amino groups, and especially in contact with an aquatic environment, the surface acquires the character of a macroscopic zwitterion, This conclusion has been confirmed by the charge titration experiment. In treatment of the experimental data from charge titration, allowance has been made for the solubility of silica. (C) 1996 Academic Press, Inc.