Plasma treatment as an effective tool for crosslinking of electrospun fibers

Abstract Electrospinning is a versatile method for the preparation of polymer fiber networks. From the medical application point of view, the stability of the fibrous structure in water is crucial. The aim of this research was to explore the possibility to induce crosslinking by treatment with non-equilibrium low pressure plasma to give structural stability to fibrous meshes. Low pressure plasma treatment was studied to induce crosslinking in allylamine-modified polysuccinimide nanofibers. Polysuccinimide was first modified with allylamine (PSI-AA) to attach the reactive allyl groups to the polymer chain. Allylamine-modification degrees varied between 10 and 100%. Then PSI-AA meshes were created by electrospinning followed by low pressure plasma treatment to allow the allylamine groups to establish crosslinks in the meshes. The crosslinked structure was confirmed by immersing both the plasma-treated, and untreated PSI-AA meshes in dimethyl sulfoxide, which is a good solvent of the non-crosslinked PSI-AA. Plasma-treated meshes kept their integrity, while the untreated samples dissolved almost immediately, which proved the formation of crosslinks due to plasma treatment. Structural changes in the meshes were studied with infrared spectroscopy (IR). X-ray photoelectron spectroscopy (XPS) investigates the structural changes on the surface of the samples and proved the presence of crosslinks. PSI-AA meshes were then hydrolyzed into poly(aspartic acid) (PASP) meshes and with the right choice of synthesis parameters (allylamine grafting degree, plasma treatment duration and power) PASP hydrogel meshes retained their fibrous structure, which was observed in SEM images of PSI-AA meshes.