Electrospinning formaldehyde-crosslinked zein solutions

Abstract

In order to develop zein fibers with improved physical properties and solvent resistance, formaldehyde was used as a crosslinking reagent before spinning. The crosslinking reaction was carried out in either acetic acid or ethanolic HCl where the amount of crosslinking reagent was between 1 and 6%. Reactions were carried out at various times and temperatures. When carried out in acetic acid, the maximum amount of formaldehyde that could be used was 1.5% as gelation occurred at higher levels. In ethanolic HCl, 6% formaldehyde could be incorporated into zein. All solutions were successfully electrospun, producing predominantly ribbon and round fibers; the morphology was strongly dependent on solvent and spinning solids. The formaldehyde-crosslinked zein fabrics had double the tensile strength of control fabrics. SDS-PAGE analysis clearly showed crosslinking had occurred. Electrospun fabrics from all formaldehyde-treated zein solutions required an additional heating step in order to be resistant to dissolution in acetic acid, a known very good solvent for zein. © 2011 Society of Chemical Industry.