Department of Chemistry and CSGI, University of Florence , Via della Lastruccia 3, 50019 Sesto Fiorentino, Florence, Italy.
Department of Chemical Science, Laboratory for Molecular Surfaces and Nanotechnology (LAMSUN), University of Catania and CSGI , Viale A. Doria 6, 95129 Catania, Italy.
Langmuir. 2017 Jun 13;33(23):5675-5684. doi: 10.1021/acs.langmuir.7b00968. Epub 2017 Jun 5.
Complex fluids composed of water, an organic solvent, and a surfactant have been recently employed as cleaning systems to remove hydrophobic materials, such as polymeric coatings, from solid surfaces. The simultaneous presence of surfactants and an organic solvent with good affinity for the polymer was proven necessary for the polymer's removal, but the comprehension of the cleaning mechanism is poorly understood. In this Article, we investigated the mechanism of removal, highlighting the specific role of each component in the interaction with the polymer film. In particular, the results from quartz crystal microbalance with dissipation monitoring (QCM-D) were compared with those obtained by using confocal microscopy to follow in situ the effect of a nanostructured fluid, i.e., a ternary formulation containing water, 2-butanone (MEK) as a good solvent for the polymer, and a nonionic surfactant (C ethoxylated alcohol, BR) on acrylic copolymer films (Paraloid B72). The results indicate a two-step process: (i) the penetration of the good solvent across the film causes the swelling of the polymer, the weakening of polymer-polymer interactions, and an increase of molecular mobility, followed by (ii) the slow adsorption of amphiphilic aggregates promoting the film detachment from the solid substrate. A different behavior is observed in the presence of similar formulations containing an anionic surfactant (sodium dodecyl sulfate, SDS), where the adsorption of SDS micelles on the surface of the polymeric film hinders solvent access into the polymer layer, rather than promoting its detachment from the solid substrate.
最近，由水、有机溶剂和表面活性剂组成的复杂流体已被用作清洁系统，以去除固体表面上的疏水性材料，如聚合物涂层。事实证明，为了去除聚合物，表面活性剂和对聚合物具有良好亲和力的有机溶剂的同时存在是必要的，但对清洁机制的理解还很不完善。在本文中，我们研究了去除机制，强调了每个组分在与聚合物膜相互作用中的特定作用。特别是，我们通过石英晶体微天平耗散监测（QCM-D）获得的结果与使用共聚焦显微镜原位跟踪纳米结构化流体（即包含水、作为聚合物良溶剂的 2-丁酮（MEK）和非离子表面活性剂（C 乙氧基化醇，BR）的三元配方）对丙烯酸共聚物膜（Paraloid B72）的影响进行了比较。结果表明存在两步过程：（i）良溶剂穿透薄膜导致聚合物溶胀，聚合物-聚合物相互作用减弱，分子迁移率增加，随后（ii）两亲性聚集体的缓慢吸附促进了薄膜从固体基底上的脱落。在含有类似的含有阴离子表面活性剂（十二烷基硫酸钠，SDS）的配方中观察到不同的行为，其中 SDS 胶束在聚合物膜表面上的吸附阻碍了溶剂进入聚合物层，而不是促进其从固体基底上脱落。
