Obtaining SiO2-–fluorinated PLA bionanocomposites with application as reversible and highly-hydrophobic coatings of buildings

Nowadays, PLA is one of the most promising alternatives to the petroleum-based polymers, since it can be obtained from renewable sources. An innovative application of PLA is to protect the exterior of buildings. PLA compounds meet an important requirement of products for conservation, which is their reversibility. This paper describes a simple procedure to create highly hydrophobic and reversible coatings. We demonstrate that water droplets produces contact angles of about 140° on a typical building marble by the combined action of roughness created by silica particles and low surface energy due to fluorine integrated in the PLA. Finally, we also demonstrate that the coatings under study preserve the aesthetic properties of the stone substrate and that they do not significantly alter stone breathability. In addition, we confirm the reversibility of the coatings by using a simple procedure (removal by an organic solvent) that can be employed in a real-life situation.