Department of Chemistry, University of Incheon, 12-1 Songdo-dong Yeonsu-gu, Incheon 406-772, Korea.
Langmuir. 2010 Jul 6;26(13):11349-54. doi: 10.1021/la1007044.
This paper describes a pH-responsive multilayer film composed of two layered components, namely poly(allylamine hydrochloride) (PAH) and a copolymer of acrylic acid and [1,3]oxazine-modified acrylate (POA). The oxazine ring is an acidochromic chromophore and opens to form either cationic 3H-indolium or anionic hemiaminal in a pH-dependent manner. This structural transition was used to generate a net positive or negative charge on the membrane for selective ion permeation. Interestingly, the reversible oxazine ring opening and closing proceeded smoothly without significant steric hindrance in the multilayer film comprising 10 PAH/POA bilayers. The pH-responsive permselectivity for cationic and anionic probe molecules was demonstrated using a POA monolayer film adsorbed electrostatically onto an amino-functionalized ITO electrode. The origin of the excellent ion-transport selectivity in the 1 nm ultrathin POA membrane is discussed in terms of alternating charges of the aromatic amphoteric group, oxazine, in the polyeletrolyte membrane.
本文描述了一种由两种层状组分组成的 pH 响应多层膜，即聚烯丙基氯化铵（PAH）和丙烯酸与[1,3]恶嗪改性丙烯酸酯（POA）的共聚物。恶嗪环是一种酸致变色生色团，在 pH 依赖性下开环形成阳离子 3H-吲哚鎓或阴离子半缩醛。这种结构转变用于在膜上产生净正电荷或负电荷，以实现选择性离子渗透。有趣的是，在包含 10 个 PAH/POA 双层的多层膜中，恶嗪环的开环和闭环反应平稳进行，没有明显的空间位阻。通过静电吸附在氨基功能化 ITO 电极上的 POA 单层膜，展示了对阳离子和阴离子探针分子的 pH 响应选择透过性。根据聚电解质膜中芳香两性基团恶嗪的交替电荷，讨论了超薄 1nm POA 膜中优异的离子传输选择性的起源。
