PROOF OF MULTILAYER STRUCTURAL ORGANIZATION IN SELF-ASSEMBLED POLYCATION POLYANION MOLECULAR FILMS
PROOF OF MULTILAYER STRUCTURAL ORGANIZATION IN SELF-ASSEMBLED POLYCATION POLYANION MOLECULAR FILMS
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DOI：
10.1016/0040-6090(94)90569-x
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发表时间：
1994-05-15
期刊：
影响因子：
2.1
通讯作者：
SCHMITT, J
中科院分区：
文献类型：
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作者：
DECHER, G;LVOV, Y;SCHMITT, J
采用两种方法研究了聚阳离子-聚阴离子自组装膜的多层结构。(1)以（ABCB）n方式交替使用三种不同的聚电解质制备聚离子超晶格，这引起X射线反射率的布拉格峰。间距d = 93.4埃对应于重复单元（ABCB）n。(2)定期对薄膜表面进行干燥处理。通常，通过在整个沉积循环中保持膜湿润来进行逐层吸附。或者，可以通过在每层吸附后在氮气或空气流中温和干燥膜来操纵膜表面。当在交替沉积聚阴离子和聚阳离子（AB）m的过程中以规则的间隔m干燥膜时（例如，对于每第6层沉积后的干燥，m = 3），在X射线反射率中观察到多达四个阶的布拉格峰。在聚（苯乙烯磺酸酯）与聚（烯丙基胺）交替的情况下，观察到的超晶格间距d（m）为d2 = 104埃，d3 = 150埃和d4 = 188埃。在这两种情况下，观察到的超晶格结构可能是由于电子密度沿着层法线在大于相邻层的界面宽度的长度尺度上的人为增强的变化。
Multilayer organization of ultrathin polycation-polyanion self-assembled films is demonstrated using two approaches. (1) Fabrication of polyion superlattices with alternation of three different polyelectrolytes in (ABCB)n fashion, which gives rise to a Bragg peak in X-ray reflectivity. The spacing d = 93.4 angstrom corresponds to the repeat unit (ABCB)n. (2) Drying-induced manipulation of the film surface at regular intervals. Normally the layer-by-layer adsorption is carried out by keeping the film wet throughout all deposition cycles. Alternatively the film surface can be manipulated by gently drying the film in a stream of nitrogen or air after the adsorption of every layer. When the films are dried at regular intervals m during the alternating deposition of a polyanion and a polycation (AB)m (e.g. m = 3 for drying after deposition of every 6th layer), up to four orders of Bragg peaks are observed in X-ray reflectivity. In the case of poly(styrenesulphonate) alternated with poly(allylamine) the observed superlattice spacings d(m) were d2 = 104 angstrom, d3 = 150 angstrom and d4 = 188 angstrom. In both cases the observation of a superlattice structure probably results from the artificially enhanced variation in electron density along the layer normal on a length scale larger than the interfacial width of adjacent layers.