Highly Efficient Dissolution of Wool Keratin by Dimethylphosphate Ionic Liquids

Ionic liquids (ILs) are eco-friendly solvents and exhibit excellent performance for dissolution and regeneration of wool keratin. In this work, a series of ILs are designed and synthesized to investigate effects of IL structures on dissolving wool keratin and properties of regenerated keratin. The results show that both cations and anions have important effects on dissolution capability for wool, while side chain lengths of imidazole cation have little effect. Structures and properties of regenerated keratin are characterized by various techniques such as Fourier transform infrared spectroscopy, nuclear magnetic resonance spectroscopy, scanning electron microscopy, thermogravimetric analysis, and X-ray diffraction. It is found that the dissolution time is shortened to 1.5 h by [Emim]DMP, the thermal stability of regenerated keratin from its solution is superior to that from the [Bmim]OAc solution, and the proportion of a-helical structure is as high as 78.7%. In addition, five cycles of [Emim]DIMP suggest that it has a good reusability, and the rheological property of DPIL solutions shows their excellent potential for fiber spinning.