Defects in a Polyelectrolyte Multilayer: The Inside Story
Defects in a Polyelectrolyte Multilayer: The Inside Story
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DOI：
10.1021/ja808135e
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发表时间：
2008-12-10
影响因子：
15
通讯作者：
Regen, Steven L.
中科院分区：
文献类型：
--
作者：
Wang, Yao;Stedronsky, Erwin;Regen, Steven L.
已经发现，用于制造多层膜（PEM）的聚（4-苯乙烯磺酸钠）（PSS）和聚（烯丙基胺盐酸盐）（PAH）的浓度的适度变化强烈影响缺陷的形成（即，间隙），如通过气体渗透选择性测量所揭示的。因此，在“高”浓度条件（重复单元中为15.0mM）下由PSS和PAH的14个交替层制成的PEM表现出大于200的He/N-2渗透选择性。与此形成鲜明对比的是，在“低”浓度条件下（重复单元中为1.0 mM）由PSS和PAH的24个交替层制成的类似厚度的类似膜没有显示出显著的He/N-2渗透选择性，反映了缺陷的存在。类似的质子交换膜，从14个交替层的PSS和PAH，使用1.0 mM的PSS和PAH在添加的NaCl的存在下，其中降低的粘度和聚合物的构象与那些在高浓度条件下发现的相匹配，表现出相同的厚度和非常相似的阻隔性能。
Moderate changes in the concentration of poly(sodium 4-styrene sulfonate) (PSS) and poly(allylamine hydrochloride) (PAH) used in fabricating polyelectrolyte multilayers (PEMs) have been found to strongly affect the formation of defects (i.e., gaps) within these films, as revealed by gas permeation selectivity measurements. Thus, PEMs made from 14 alternating layers of PSS and PAH under "high" concentration conditions (15.0 mM in repeat units) exhibit He/N-2 permeation selectivities that are greater than 200. In sharp contrast, analogous films of similar thickness that are made from 24 alternating layers of PSS and PAH under "low" concentration conditions (1.0 mM in repeat units) showed no significant He/N-2 permeation selectivity, reflecting the presence of defects. Analogous PEMs that were fabricated from 14 alternating layers of PSS and PAH, using 1.0 mM PSS and PAH in the presence of added NaCl, where reduced viscosities and polymer conformations were matched with those found under high concentration conditions, exhibited the same thicknesses and very similar barrier properties.