Department of Chemistry, University of Toronto, 80 St. George Street, Toronto, Ontario M5S 3H6, Canada.
J Phys Chem B. 2010 Mar 11;114(9):3085-94. doi: 10.1021/jp9118875.
We describe fluorescence resonance energy transfer (FRET) experiments carried out to examine the effect of ethylene glycol and propylene glycol on the early stages of polymer diffusion in poly(butyl acrylate-co-methyl methacrylate) latex films. In our approach, we temporarily arrest the drying process of a wet latex film by sealing the film in a previously cooled airtight sample chamber. This arrests propagation of the drying front and suppresses polymer diffusion during the measurements. We then measure donor fluorescence decays from 0.5 mm diameter spots at various locations on the film. From our analysis, we obtain information about the earliest stages of polymer diffusion as the film is still drying. We also investigate the effect of these glycols on polymer diffusion at longer aging times on predried latex films. Ethylene glycol and propylene glycol retard polymer diffusion at early times immediately after the passing of the drying front but enhance the rate of polymer diffusion at later aging times. This behavior is described quantitatively in terms of free-volume theory and the partitioning of the glycols between the aqueous and polymer phases in the film.
我们描述了荧光共振能量转移（FRET）实验，以研究乙二醇和丙二醇对聚（丙烯酸丁酯-甲基丙烯酸甲酯）乳胶膜中聚合物扩散早期阶段的影响。在我们的方法中，通过将膜密封在预先冷却的密封样品室内，暂时阻止湿乳胶膜的干燥过程。这阻止了干燥前沿的扩展，并在测量过程中抑制了聚合物的扩散。然后，我们从膜上各个位置的 0.5 毫米直径斑点测量供体荧光衰减。通过我们的分析，我们获得了有关膜仍在干燥时聚合物扩散的最早阶段的信息。我们还研究了这些二醇在预干燥乳胶膜上更长老化时间对聚合物扩散的影响。乙二醇和丙二醇在干燥前沿通过后立即减缓聚合物的扩散，但在后期老化时间内提高聚合物扩散的速率。这种行为可以根据自由体积理论和二醇在膜中的水相和聚合物相之间的分配来定量描述。
