Biobased System Composed of Electrospun sc-PLA/POSS/Cyclodextrin Fibers To Remove Water Pollutants

In this work, a novel biobased system, characterized by specific features suitable for the removal of water pollutants, was developed. Indeed, the system consists of electrospun stereocomplex polylactide (sc-PLA)-based fibers, prepared from solutions containing equimolar amounts of high-molecular-weight poly(l-lactide) (PLLA) and poly(d-lactide) (PDLA), functionalized with an amino polyhedral oligomeric silsesquioxanes (POSS-NH2), which was added directly into the electrospinning solution. The sc-PLA/POSS-NH2 fibers, characterized by a submicrometric dispersion of the silsesquioxanes, underwent a grafting reaction with β-cyclodextrin molecules, activated to nucleophilic substitution via monotosylation (CD-O-Ts). The reaction was first investigated on neat POSS-NH2 and optimized conditions were then applied for sc-PLA/POSS-NH2 fibers. Indeed, IR and XPS measurements demonstrated the formation of a novel hybrid molecule, characterized by the linkage of the cyclodextrin to the silsesquioxane siliceous cage (POSS-NH-CD). Concerning the fibers, SEM measurements evidenced that the treated mats show a higher surface roughness than the neat ones, whereas by applying TGA analysis it was possible to evaluate the amount of the grafted cyclodextrin, which was found to be 3 wt %, that is a quantity correlated with the concentration of POSS-NH2 in the fibers (5 wt %). Moreover, the surface wettability of the fibers turned out to increase as a consequence of the surface grafting. Finally, UV measurements demonstrated the capacity of the novel synthesized hybrid molecule, based on POSS and cyclodextrin, to absorb water pollutants, by having chosen, as model compounds, alizarin red and 2-chlorophenol. Indeed, it was demonstrated that the grafting of CD on the surface of sc-PLA/POSS-NH2 fibers enhanced the absorption capacity of the system.