School of Materials Science and Engineering , Georgia Institute of Technology, Atlanta, Georgia 30332, USA.
Langmuir. 2010 May 18;26(10):7138-47. doi: 10.1021/la9042099.
We report on multilayer layer-by-layer (LbL) films of the conjugated polymer sodium poly[2-(3-thienyl)ethyloxy-4-butylsulfonate] (PTH) assembled with polycations: poly(diallyldimethylammonium chloride) (PDDA), 20% quaternized poly(N-ethyl-4-vinylpyridinium bromide) (Q20), poly(ethylene imine) (PEI), and poly(allylamine hydrochloride) (PAH). These films were prepared through spin-assisted LbL assembly under various pH conditions. We demonstrated a crucial role of the deposition pH in formation of PTH/polycation films and showed that decrease in the deposition pH from 7.5 to 2.5 limits the PTH multilayer formation to Q20/PTH and PDDA/PTH films due to reduced charge density in the poly(thiophene) chains. We show that optical and surface properties of the resulting PTH/polycation films can be tuned by varying a polycation component and/or by varying the deposition pH. The fluorescence properties of the Q20/PTH, PEI/PTH, and PDDA/PTH films are pH-dependent, and the films exhibit the drastic changes in photoluminescent intensity when transferred into solutions with different pH values, which may find useful in optical sensing applications.
我们报告了通过逐层（LbL）组装方法制备的共轭聚合物聚[2-(3-噻吩基)乙氧基-4-丁基磺酸酯]钠盐（PTH）与聚阳离子：聚二烯丙基二甲基氯化铵（PDDA）、20%季铵化聚（N-乙基-4-乙烯基溴化吡啶）（Q20）、聚乙烯亚胺（PEI）和聚（烯丙基胺盐酸盐）（PAH）的多层膜。这些薄膜是在不同 pH 值条件下通过旋转辅助 LbL 组装制备的。我们证明了沉积 pH 值在 PTH/聚阳离子薄膜形成中的关键作用，并表明沉积 pH 值从 7.5 降低至 2.5 会由于聚（噻吩）链中的电荷密度降低，限制了 PTH 多层结构的形成仅限于 Q20/PTH 和 PDDA/PTH 薄膜。我们表明，可以通过改变聚阳离子组分和/或改变沉积 pH 值来调节所得 PTH/聚阳离子薄膜的光学和表面性质。Q20/PTH、PEI/PTH 和 PDDA/PTH 薄膜的荧光性质是 pH 值依赖性的，当将这些薄膜转移到具有不同 pH 值的溶液中时，其荧光强度会发生剧烈变化，这在光学传感应用中可能很有用。
