Study on preparation and adsorbability of dicationic LB film

研究了单阳离子烷基铵盐、双阳离子烷基铵盐和烷基胺阳离子LB膜的制备及其吸附性能。首先，研究了一系列单阳离子烷基铵盐[硬脂基三甲基氯化铵（SAC）、十二烷基三甲基氯化铵（DAC）、二硬脂基二甲基铵（DSAC）、三硬脂基甲基氯化铵（TSAC）]、双阳离子烷基铵盐（XSAC）和原十八烷基胺（ODA）]在水相上阳离子单层膜的成膜性能。由于铵基具有较强的亲水性，长链的SAC和DAC的单分子膜倾向于溶解到亚相中，而具有两条或三条硬脂基链的DSAC、TSAC和XSAC形成稳定的单分子膜。另一方面，ODA在pH大于10.1的亚相上形成稳定的单层。π- a等温线表明，TSAC、XSAC和ODA的单分子层在水相中与MO和NO有较强的相互作用。制备了保留阳离子性质的TSAC、XSAC和ODA三种LB膜，研究了不同价态和不同离子性质LB膜的吸附特性。结果表明，阳离子LB膜对带负电荷的NO、mo等染料离子具有较高的吸附性能，其吸附行为受LB膜中烃类链的排列方式和染料水溶液pH值的影响。然而，染料的吸附几乎是通过离子相互作用进行化学计量的。这些事实表明，阳离子LB膜可以吸附其他带负电荷的吸附剂，如功能化分子、分散颗粒等。此外，MO和NO在阳离子LB膜中的吸附状态明显不同，即MO在膜表面呈边向构型，而NO在XSAC LB膜中表现为平躺构型。这可能是由于MO和NO的分子结构不同，因此，通过设计吸附物的分子结构，提出了将染料分子结合到膜中的能力。该研究获得的分子排列信息有望有助于理解各种吸附剂在阳离子LB - Glms上的吸附行为。这项研究也被认为有助于LB基质中功能吸附剂的新功能的出现。如光诱导异构化、聚合等。少

This study is concerned with the preparation and adsorbability of cationic LB films of monocationic alkylammonium salts, dicationic alkylammonium salt and alkylamine.At first, the film-forming properties of the cationic monolayers on the aqueous subphase were examined for a series of monocationic alkylammonium salts [Stearyltrimethylammonium chloride (SAC), docosyltrimethylammonium chloride (DAC), Distearyldimethylammonium (DSAC), Tristearylmethylammonium chloride (TSAC)], dicationic alkylammonium salt (XSAC) and primary octadecylamine (ODA). Owing to the strong hydrophilic property of the ammonium group, the monolayers of SAC and DAC having a long-chain tended to dissolve into the subphase, while DSAC, TSAC and XSAC having two or three stearyl chains formed the stable monolayers. On the other hand, ODA formed the stable monolayer on the subphase above pH 10.1. Theπ-A isotherm showed that the monolayers of TSAC, XSAC and ODA interacted strongly with MO and NO in the aqueous subphase.Th … More e LB films of TSAC, XSAC and ODA were fabricated with preserving the cationic property, and subsequently the adsorption characteristics of these LB films, being different in their valency as well as ionic property, were investigated. It was found that the cationic LB films showed high adsorbability for the negatively-charged dye ions such as NO and MO.The adsorption behavior was influenced by the packing of the hydrocarbon chain in the LB film and the pH value of aqueous dye solutions. Nevertheless, the adsorption of dyes occurred almost stoichiometrically by the ionic interaction. These facts imply that the cationic LB film would adsorb the other negatively-charged adsorbates, e. g., functionalized molecules, dispersed particle, etc. Moreover, distinction in the adsorbing state was obviously obscrved for MO and NO in the cationic LB films, i. e., MO took the edge-on configuration with respect to the film surface, while NO exhibited the lie-flat configuration typically in the XSAC LB film. This is probably due to the differerece in the molecular structure between MO and NO, and therefore, capability of incorpolation of dye molecules in the film with desired orientation was suggested by designing the molecular structure of adsorbate.Information on the molecular arrangement obtained in tits study is expected to be helpful for understanding the adsorption behavior of various adsorbates on the cationic LB Glms. This study is also considered to contribute to the appearance of new functionality of the functional adsorbates in the LB matrix. as be exemplified by photoinduced isomerization, polymerization and so on. Less