CRUMPLED AND COLLAPSED CONFORMATIONS IN GRAPHITE OXIDE MEMBRANES
CRUMPLED AND COLLAPSED CONFORMATIONS IN GRAPHITE OXIDE MEMBRANES
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DOI：
10.1038/355426a0
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发表时间：
1992-01-30
期刊：
影响因子：
64.8
通讯作者：
TANAKA, T
中科院分区：
文献类型：
--
作者：
WEN, X;GARLAND, CW;TANAKA, T
由两亲物如磷脂的双层组成的膜通常在层内表现出二维液体状结构。当这种膜的组成分子彼此永久交联时，膜变得不那么柔韧，形成二维固体。预计固体膜表现出与它们的液体对应物1-3非常不同的行为，包括二维平坦相、分形维数为2.5的褶皱相和致密的三维相之间的转变。然而，一直缺乏关于褶皱阶段的实验证据。由于在计算机模拟4-6中没有观察到该相，因此已经提出对于自回避（并且因此所有真实的）膜4-6，它可能总是不存在。相反，我们在这里报告的实验观察氧化石墨膜的水悬浮液中的褶皱构象。静态光散射测量表明存在分形维数为2.54 +/- 0.05的膜构象。由于通过改变溶剂的组成来增强膜内亲和力，因此膜塌陷成紧凑的构型。
MEMBRANES composed of bilayers of amphiphiles such as phospholipids generally exhibit two-dimensional liquid-like structure within the layers. When the constituent molecules of such a membrane are permanently cross-linked to each other, the membrane becomes less flexible, forming a two-dimensional solid. Solid membranes are expected to exhibit very different behaviour from their liquid counterparts 1-3, including transitions between a two-dimensional flat phase, a crumpled phase of fractal dimension 2.5 and a compact, three-dimensional phase. Experimental evidence for the crumpled phase has, however, been lacking. As this phase was not observed in computer simulations 4-6, it has been suggested that it may always be absent for self-avoiding (and therefore all real) membrane 4-6. To the contrary, we report here the experimental observation of the crumpled conformation in an aqueous suspension of graphite oxide membranes. Static light scattering measurements indicate the presence of membrane conformations with a fractal dimension of 2.54 +/- 0.05. As the intra-membrane affinity is enhanced by changing the composition of the solvent, the membranes collapse to a compact configuration.