Biobased Protic Ionic Liquids as Sustainable Solvents for Wool Keratin/Cellulose Simultaneous Dissolution: Solution Properties and Composited Membrane Preparation

Abstract

In this study, levulinic acid-derived protic ionic liquids (PILs) were identified to be good solvents for wool keratin fiber dissolution and the simultaneous dissolution of wool keratin and cellulose, implying a green dissolution processing platform for regenerated materials preparation derived from both cellulose and keratin. The satisfactory solubility was believed to correlate to the potential keto–enol tautomerism of the ketone group in the levulinate anion, which has particular hydrogen bonding forming ability with cellulose and wool keratin. Cellulose/wool keratin solution properties were first studied systematically, demonstrating that the apparent viscosities of cellulose/wool keratin solution were highly correlated to the mass ratio of cellulose to wool keratin, mass concentration, and test temperature. The values of overlap concentration (C*) were identified to be 0.83, 1.3, and 2.01 wt % in the cases of cellulose, cellulose/wool keratin (5/5), and pure wool keratin, respectively. The aggregation that arose by the potential interaction via hydrogen bonding among cellulose, wool keratin, as well as PILs was demonstrated by dynamic light scattering. Furthermore, the cellulose/wool keratin composite membrane was facilely cast through sol–gel transition when ethanol was used as the coagulation bath, and the membranes were systematically characterized by X-Ray diffraction, Fourier transform infrared spectroscopy (FTIR), thermo gravimetric analysis, as well as scanning electron microscopy. The findings demonstrated that cellulose and wool keratin had high compatibility in the composited membranes. Meanwhile, the composite membranes had satisfactory mechanical properties of tensile strength of up to 60 MPa and an elongation at a break of up to 6%. In addition, the composited membranes also have outstanding oxygen barrier performance and satisfactory thermostability.

Preparation of high‐strength, high‐modulus PVA fiber by synthesis of syndiotacticity‐rich high molecular weight PVA polymers with VAc and VBz via emulsifier‐free emulsion polymerization

“…There was a significant vibrational peak associated with OH stretching in the 3491–3442 cm −1 range and absorption bands associated with CH 2 and CO stretching vibrations at around 2975 and 1062 cm −1 , respectively 29,30 . If the intermolecular hydrogen bonding is larger than the strength of the intramolecular hydrogen bonding, and vice versa, the associated hydroxyl band will shift toward a lower wavenumber 31,32 . With increasing VBz ratios, it was revealed that the peak of the OH stretching vibration absorption shifted from 3491 cm −1 to a lower wavenumber of 3442 cm −1 .…”

“…29,30 If the intermolecular hydrogen bonding is larger than the strength of the intramolecular hydrogen bonding, and vice versa, the associated hydroxyl band will shift toward a lower wavenumber. 31,32 With increasing VBz ratios, it was revealed that the peak of the OH stretching vibration absorption shifted from 3491 cm À1 to a lower wavenumber of 3442 cm À1 . This is mainly due to the special structure of the benzene ring on the side group of VBz has a great steric hindrance effect, 27 during the polymerization, the arrangement structure of the side groups of the original prepolymer was changed, and more hydrogen bonds were formed between the OH groups after alcoholysis.…”

Preparation Methods and Functional Characteristics of Regenerated Keratin-Based Biofilms

“…The disadvantages of this method are that it is time consuming and can easily introduce impurities. In order to improve the properties of keratin-based biofilms, many natural polymers as modifiers, such as sodium alginate, gelatine, chitosan, cellulose, pullulan, and silk fibroin may be introduced into the casting solution [ 102 , 103 , 104 , 105 , 106 , 107 , 108 ].…”

Regulations of hydrophilicity of cellulosic nanosheets by polarity of coagulation bath

“…But using cellulous entirely "naturally" limits its usefulness (He et al 2022), it is worth noting that the high value utilization of cellulose requires dissolution and regeneration processes (Acharya et al 2021). Usually, the solution processing route includes structural dissociation (Deng et al 2022) and regeneration (Sirviö 2019), and the regenerated structures decide the properties and applications of the cellulosic materials (Qiu et al 2022).…”