Ionic Liquid Property Effects on the Natural Fiber Welding Process

Natural Fiber Welding (NFW) is a versatile biopolymer manipulation process that uses ionic liquids (ILs) to disrupt the intermolecular interactions between polymer strands, enabling structural reconfiguration. This process is thought to require ILs that have both chaotropic anions and hydrogen bond donating cations, with past work focusing on ILs that have been shown to be solvents capable of the full dissolution of biopolymer materials (e.g. cotton, silk, linen, and keratin). In the present work, we looked to expand the suite of ILs that could be used for NFW by investigating ILs that are not known to be good biopolymer solvents. We looked at how replacing the cation of 1-ethyl-3-methylimidazolium acetate (EMIAc), an IL capable of NFW, with the 1-ethyl-1-methylpyrolidinium cation would impact the welding process. Confocal fluorescence microscopy (CFM) and scanning electron microscopy (SEM) were used to evaluate the level of welding in the IL-treated cotton yarns. We show that NFW may not require the use of an IL with a hydrogen bond donating cation as long as a chaotropic anion is present.