Sorrell Courtney D, Lyon L Andrew
School of Chemistry and Biochemistry & Petit Institute for Bioengineering and Bioscience, Georgia Institute of Technology, Atlanta, Georgia 30332-0400, USA.
J Phys Chem B. 2007 Apr 26;111(16):4060-6. doi: 10.1021/jp069057j. Epub 2007 Apr 4.
A series of studies on microgel thin films is described, wherein quartz crystal microgravimetry (QCM), surface plasmon resonance (SPR), and atomic force microscopy (AFM) have been used to probe the properties of microstructured polymer thin films as a function of film architecture and solution pH. Thin films composed of pNIPAm-co-AAc microgels were constructed by using spin-coating layer-by-layer (scLbL) assembly with poly(allylamine hydrochloride) (PAH) as a polycationic "glue". Our findings suggest that the interaction between the negatively charged microgels and the positively charged PAH has a significant impact on the pH responsivity of the film. These effects are observable in both the optical and mechanical behaviors of the films. The most significant changes in behavior are observed when the motional resistance of a quartz oscillator is monitored via QCM experiments. Slight changes to the film architecture and alternating the pH of the environment significantly changes the QCM and SPR responses, suggesting a pH-dependent swelling that is dependent on both particle swelling and polyelectrolyte de-complexation. Together, these studies allow for a deeper understanding of the morphological changes that take place in environmentally responsive microgel-based thin films.
本文描述了一系列关于微凝胶薄膜的研究，其中石英晶体微天平（QCM）、表面等离子体共振（SPR）和原子力显微镜（AFM）被用于探究微结构聚合物薄膜的性质与薄膜结构及溶液pH值的关系。由聚（N-异丙基丙烯酰胺-co-丙烯酸）（pNIPAm-co-AAc）微凝胶组成的薄膜通过旋涂逐层（scLbL）组装法制备，使用聚（烯丙胺盐酸盐）（PAH）作为聚阳离子“粘合剂”。我们的研究结果表明，带负电荷的微凝胶与带正电荷的PAH之间的相互作用对薄膜的pH响应性有显著影响。这些影响在薄膜的光学和力学行为中都可观察到。当通过QCM实验监测石英振荡器的运动阻力时，观察到行为上最显著的变化。薄膜结构的微小变化以及环境pH值的改变会显著改变QCM和SPR响应，表明存在一种依赖于颗粒溶胀和聚电解质解络合的pH依赖性溶胀。总之，这些研究有助于更深入地理解基于环境响应性微凝胶的薄膜中发生的形态变化。
