Binary Diamondoid Building Blocks for Molecular Gels

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• 作者：Mengwen Zhang ; Charles F. Zukoski
• 刊名：Langmuir
• 出版年：2014
• 出版时间：July 1, 2014
• 年：2014
• 卷：30
• 期：25
• 页码：7540-7546
• 全文大小：353K
• ISSN：1520-5827

文摘

Adamantane is a type of diamondoid molecules that has a cage or globular shape with a diameter of 6.34 卤 0.04 脜.8 Anisotropic interactions between these truly nanoscopic particles can be induced through the derivatization of the diamondoid cage. Here we explore the gelation of paired systems of adamantane where attractions are introduced through van der Waals forces and hydrogen bonding. Gels are produced through the mixing of 1-adamantanecarboxylic acid (A1C) and 1-adamantylamine (A1N). Upon mixing dimethyl sulfoxide solutions of these molecules at vanishing concentrations, these diamondoid molecules rapidly precipitate. A space-filling gel of the resulting aggregates is observed at approximately 3% by weight. These resulting gels have elastic moduli of 10²鈥?0⁴ Pa in the 3鈥? wt % concentration range. At a 1:1 mol ratio of 1-adamantanecarboxylic acid (A1C) and 1-adamantylamine (A1N), the gel鈥檚 elastic modulus and yield stress increase as volume fractions ^x and ^y with x 鈮?4.2 and y 鈮?3.5. The dependencies of moduli and yield stress on the volume fraction display characteristics of colloidal gels. Transmission electron microscope (TEM) images indicate that the gels are formed from a network of interwoven and branched fibers which are composed of 30 nm crystallites that have undergone oriented aggregation to form fibers.