Jiang Yan, Wu Peiyi
The Key Laboratory of Molecular Engineering of Polymers (Ministry of Education) and Department of Macromolecular Science, Fudan University, Shanghai 200433, People's Republic of China.
Appl Spectrosc. 2008 Feb;62(2):207-12. doi: 10.1366/000370208783575555.
Layer-by-layer (LBL) ultra-thin films have been assembled by alternate adsorption of poly(3-thiophene acetic acid) (PTAA) and poly(4-vinyl-pyridine) (P4VP) on planar quartz slides via hydrogen-bonding interaction. Subsequently, the multilayers can be controllably removed by changing the pH values of the aqueous solutions used for film immersion. Our present study is an attempt to reveal the mechanisms of the multilayer film with two-dimensional (2D) ultraviolet-visible (UV-vis) correlation spectroscopy. UV-vis spectroscopy is primarily employed here to monitor the buildup and removal of the ultra-thin films. 2D correlation analysis is performed on the basis of the corresponding spectra for further studies. The morphology of the multilayer film is characterized by atomic force microscopy (AFM). When eliminated in alkaline and acidic aqueous solutions, the polymers in the films show diverse phenomena mainly due to the different extents of dissociation of PTAA and protonation of P4VP at different pH values. In alkaline solution, the elimination of PTAA takes place before P4VP, while in acid solution, the removal of these two polymers adopts a reverse order.
通过聚（3-噻吩乙酸）（PTAA）和聚（4-乙烯基吡啶）（P4VP）经由氢键相互作用在平面石英载玻片上交替吸附，组装了逐层（LBL）超薄膜。随后，通过改变用于膜浸泡的水溶液的pH值，可以可控地去除多层膜。我们目前的研究旨在通过二维（2D）紫外可见（UV-vis）相关光谱揭示多层膜的机制。这里主要采用UV-vis光谱来监测超薄膜的形成和去除。基于相应光谱进行二维相关分析以作进一步研究。多层膜的形态通过原子力显微镜（AFM）表征。当在碱性和酸性水溶液中去除时，膜中的聚合物表现出不同的现象，这主要是由于PTAA在不同pH值下的解离程度和P4VP的质子化程度不同。在碱性溶液中，PTAA的去除先于P4VP，而在酸性溶液中，这两种聚合物的去除顺序相反。
