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首页> 外文期刊>The journal of physical chemistry, B. Condensed matter, materials, surfaces, interfaces & biophysical >Uniaxial Stress and Sol Concentration Dependence of the Structure of a Dressed Macroion in a Dilute Electrolyte Solution
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Uniaxial Stress and Sol Concentration Dependence of the Structure of a Dressed Macroion in a Dilute Electrolyte Solution

机译：稀电解质溶液中修整过的小分子的结构的单轴应力和溶胶浓度依赖性

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摘要

Vermiculite clay gels in 0.03 M butylammonium chloride solution were studied by neutron diffraction in the Q range 0.02-2.2 A~(-1), permitting a determination of both the distance between the clay platelets (the d spacing) and the intermediate-range structure of the interlayer solution. The structure was investigated as a function of the fraction of the clay in the condensed matter system (r) and the applied uniaxial pressure along the swelling axis (p). The d spacing of about 170 A at zero pressure and r ～ 0.01 reduces dramatically with both increasing pressure and increasing r value without changing the interlayer structure significantly. For r = 0.39 a remarkably low d value of about 50 A was obtained for a gel in equilibrium with a crystalline phase. The existence of such an equilibrium is a counterexample to DLVO theory but well accounted for by Sogami theory. Independent of the pressure, r value, and salt concentration, the clay surfaces are covered by an about 6 A thick layer of water molecules, and the majority of the butylammonium chains sit outside this water layer and form an approximately 4-5 A thick layer located 12-16 A from the center of the clay platelets, giving us a picture of a dressed macroion. Continuum electrical theories of clay swelling can thus only be valid at distances greater than the 35-40 A thickness of the clay platelet plus adsorbed layers of water molecules and counterions. Further, the results suggest that 35 A is about the lowest possible d spacing that can be achieved for the gel phase by either increasing the uniaxial pressure toward infinity or using a sufficiently high sol concentration.
机译：通过中子衍射在Q范围0.02-2.2 A〜（-1）中研究了0.03 M丁基氯化铵溶液中的石粘土凝胶，从而可以确定粘土薄片之间的距离（d间距）和中间范围结构中间层解决方案。研究了该结构与粘土在冷凝物系统中的比例（r）和沿溶胀轴（p）施加的单轴压力的函数关系。在零压力和r〜0.01时，大约170 A的d间距随着压力的增加和r值的增加而显着减小，而不会显着改变层间结构。对于r ＝ 0.39，对于与结晶相平衡的凝胶，获得约50A的非常低的d值。这种平衡的存在是DLVO理论的反例，但被Sogami理论很好地解释了。与压力，r值和盐浓度无关，粘土表面覆盖着约6 A厚的水分子层，大多数丁基铵链位于该水层的外面并形成约4-5 A的厚层位于粘土血小板中心12-16 A处，这给了我们一张打扮得很饱满的小巨人的照片。因此，粘土溶胀的连续电学理论仅在大于粘土薄片厚度加上水分子和抗衡离子吸附层的35-40 A的距离时才有效。此外，结果表明35 A约为凝胶相的最低可能d间距，这可以通过增加单向无穷大的单轴压力或使用足够高的溶胶浓度来实现。

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