Gopinadhan Manesh, Ivanova Oxana, Ahrens Heiko, Günther Jens-Uwe, Steitz Roland, Helm Christiane A
Institut für Physik, Ernst-Moritz-Arndt Universität, Felix-Hausdorff-Strasse 6, 17487 Greifswald, Germany.
J Phys Chem B. 2007 Jul 26;111(29):8426-34. doi: 10.1021/jp067402z. Epub 2007 Apr 27.
With X-ray and neutron reflectivity, the structure and composition of polyelectrolyte multilayers from poly(allyl amine) (PAH) and poly(styrene sulfonate) (PSS) are studied as function of preparation conditions (salt concentration and solution temperature, T). The onset of a temperature effect occurs at 0.05 M NaCl (Debye length approximately 1 nm). At 1 M salt, the film thickness increases by a factor of 3 on heating the deposition solution from 5 to 60 degrees C. The PAH/PSS bilayer thickness is independent of the kind of salt (NaCl or KCl), yet its composition is different (more bound water for NaCl). At low T, the internal roughness is 33% of the bilayer thickness; it increases to 60% at high T. The roughening is accompanied by a total loss of bound water. At which temperature the roughening starts is a function of the kind of salt (50 degrees C for NaCl and 35 degrees C for KCl). The strong temperature dependence and the eventual loss of bound water molecules may be attributed to the hydrophobic force; however, there is an isotope effect, since the loss of bound water is less pronounced in the deuterated layers.
利用X射线和中子反射率，研究了聚烯丙胺（PAH）和聚苯乙烯磺酸盐（PSS）形成的聚电解质多层膜的结构和组成与制备条件（盐浓度和溶液温度T）的关系。温度效应在0.05 M NaCl（德拜长度约为1 nm）时开始出现。在1 M盐的情况下，将沉积溶液从5℃加热到60℃时，膜厚度增加了2倍。PAH/PSS双层膜的厚度与盐的种类（NaCl或KCl）无关，但其组成不同（NaCl的结合水更多）。在低温下，内部粗糙度为双层膜厚度的33%；在高温下增加到60%。粗糙度增加的同时结合水会全部丧失。粗糙度开始出现的温度取决于盐的种类（NaCl为50℃，KCl为35℃）。强烈的温度依赖性以及最终结合水分子的丧失可能归因于疏水作用力；然而，存在同位素效应，因为在氘代层中结合水的丧失不太明显。
