Electrospun polyampholyte nanofibers with different hydrophobic and ionic chain densities

We have successfully electrospun highly-tunable neutral, positively charged, and negatively charged polyampholyte copolymers into fibrous membranes, with an emphasis on understanding the entanglement, solubility, fiber morphology, and fiber diameter characteristics of these copolymers. These polyampholyte copolymer variants contain hydrophobic, anionic, and cationic side chains of different molar concentrations that alter material properties, in part due to the differences in monomeric unit charge and chain-entanglement mechanisms. The hydrophobicity of nanofibrous mats was investigated using sessile drop water contact angle measurements, for their targeted application as filtration membranes. For producing nanofibers, a horizontal electrospinning set-up with a rotating collector plate was utilized. Using specific solvent mixtures for each copolymer variant, repeatable electrospinning methods for producing polyampholyte nanofibers were achieved. Electrospun fibers of the neutral charged copolymer have diameters ranging from 0.2 µm to 8.0 µm, with distinct morphologies under different experimental and solvent conditions, such as circular cross-section, flat, and beaded fibers. In this study, the solubilities of the polyampholyte copolymer variants were studied closely in various solvent mixtures for the purpose of creating ideal solutions for electrospinning through an evaluation of viscosity, surface tension, and perceived electrohydrodynamic behavior.