Reusable and Interface-Confined Photothermal Electrospun Nonwovens for the Selective Removal of Polymeric Coatings

The selective removal of polymeric coatings from multilayer films can be challenging when the outer layer is highly insoluble and chemically similar to the underlying layers. In this context, photothermal materials represent a promising strategy for locally activating polymer softening. In this paper, we studied heat delivery at solid-solid interfaces in a bioderived electrospun nonwoven incorporating melanin nanoparticles as a photothermal agent for the selective removal of polymeric coatings applied to a multilayer system. Through controlled solvent loading and light-induced photothermal heating, a localized temperature modulation at the material-substrate interface can be achieved. A dedicated experimental setup integrating thermal imaging and thermocouple measurements enables direct quantification of interface temperatures under operational conditions. As a proof of concept, the method has been applied to remove a highly insoluble cross-linked alkidic layer applied on an underlying acrylic or alkyd polymer coatings. The efficacy and selectivity of the proposed method have been assessed using a multianalytical protocol that combines imaging techniques with chemometric analysis, HPLC-DAD, and Brillouin microspectroscopy. The synergistic action of photothermally generated heat and the solvent allowed reducing both the amount of solvent used and the application time, while preserving the chemical composition and viscoelastic properties of the underlying layers. Additionally, the electrospun nonwovens remained effective after three cleaning cycles. These results demonstrate that photothermal electrospun nonwovens provide a versatile platform for interface-confined thermal activation, offering new opportunities for selectively removing organic coatings from multilayer systems.