Electrospinning of immiscible systems: The wool keratin/polyamide-6 case study

Blends of wool keratin and polyamide 6 (PA6) have shown interesting adsorbent properties in filtration. In this work, the miscibility of keratin and PA6 was studied for the first time through rheological measurements of diluted blend solutions. In particular, the immiscibility between the two polymers in different blend proportions was observed by the segregation of phases in the cast films. Nevertheless, notwithstanding the immiscibility, we demonstrate here that homogeneous keratin/PA6 blend nanofibers can be obtained by electrospinning as a result of rapid solvent evaporation, where kinetic effects prevail on thermodynamic effects, thereby avoiding phase segregation. The obtained nanofibers have diameters ranging from 100 to 250 nm, depending on the experimental conditions. We show, through a principal component analysis (PCA) that the percentage of keratin represents the most important variable to determine nanofiber diameters. Collectively, this study represents a successful case of immiscible electrospinning system for production of useful nanofibers as adsorbent material for different applications.