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, quartz crystal microbalance with dissipation monitoring (QCM-D) and confocal microscopy were coupled to follow in situ the effect of a nanostructured fluid containing water, 2-butanone (MEK) as a good solvent for the polymer, and a nonionic surfactant (C9-11 ethoxylated alcohol, BR) on acrylic copolymer films. 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.
Probing the cleaning action of nanostructured fluids on polymeric coatings: a QCM-D study
In corso di stampa
Abstract
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, quartz crystal microbalance with dissipation monitoring (QCM-D) and confocal microscopy were coupled to follow in situ the effect of a nanostructured fluid containing water, 2-butanone (MEK) as a good solvent for the polymer, and a nonionic surfactant (C9-11 ethoxylated alcohol, BR) on acrylic copolymer films. 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.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
