Structural and Morphological Properties of Wool Keratin and Cellulose Biocomposites Fabricated Using Ionic Liquids

Abstract

In this study, the structural, thermal, and morphological properties of biocomposite films composed of wool keratin mixed with cellulose and regenerated with ionic liquids and various coagulation agents were characterized and explored. These blended films exhibit different physical and thermal properties based on the polymer ratio and coagulation agent type in the fabrication process. Thus, understanding their structure and molecular interaction will enable an understanding of how the crystallinity of cellulose can be modified in order to understand the formation of protein secondary structures. The thermal, morphological, and physiochemical properties of the biocomposites were investigated by Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), thermal gravimetric analysis (TGA), differential scanning calorimetry (DSC), and X-ray scattering. Analysis of the results suggests that both the wool keratin and the cellulose structures can be manipulated during dissolution and regeneration. Specifically, the β-sheet content in wool keratin increases with the increase of the ethanol solution concentration during the coagulation process; likewise, the cellulose crystallinity increases with the increase of the hydrogen peroxide concentration via coagulation. These findings suggest that the different molecular interactions in a biocomposite can be tuned systematically. This can lead to developments in biomaterial research including advances in natural based electrolyte batteries, as well as implantable bionics for medical research.

Physico-Chemical Characterization of Keratin from Wool and Chicken Feathers Extracted Using Refined Chemical Methods

“…As regards more specifically SAXS spectra, apart from the aforementioned higher degree of lateral aggregation for feather keratin, no significant changes in the broadness of peaks are observed between the two sources. This is promising for the production of composite films with other polymers (e.g., cellulose), where the structural variability these changes may imply do represent an issue [ 43 ]. As the result, a single model has been hypothesized as sufficiently representative for both keratins.…”

Ionic-liquid-processed keratin-based biocomposite films with cellulose and chitin for sustainable dye removal

“…The samples were decomposed between 160 °C and 360 °C, with a slow degradation, divided into steps, thus indicating physical interactions, and no chemical interactions, between the biopolymers (the thermal degradation of cellulose and chitin correspond to 335 °C (ref. 40) and 253 °C, 41 respectively). The starting decomposition at 160 °C can be related to glycerol evaporation (boiling temperature = 182 °C).…”

Biodegradable Cellulose/Polycaprolactone/Keratin/Calcium Carbonate Mulch Films Prepared in Imidazolium-Based Ionic Liquid

“…Conversely, biocomposite films containing these same components, KER/GCC, show an increase in melting temperature ( Table 3 ), which is possibly due to the combination of two phenomena: mutual macromolecular interaction of the starting components ( Figure S4, Supplementary Materials ) and increased heat capacity when GCC is present, resulting in heating delay due to thermal absorption, i.e., an effect of the amount of thermal energy required to raise the temperature and so dependent on the rate of heating ( Figure S5, Supplementary Materials ). A higher melting temperature of the combination CELL/PCL/KER versus both PCL alone and in the CELL/PCL blend is mostly influenced by the presence of cellulose, while the secondary structures within the keratin contribute to the amorphous regions [ 27 ].…”

“…Conversely, biocomposite films containing these same components, KER/GCC, show an increase in melting temperature (Table 3), which is possibly due to the combination of two phenomena: mutual macromolecular interaction of the starting components (Figure S4, Supplementary Materials) and increased heat capacity when GCC is present, resulting in heating delay due to thermal absorption, i.e., an effect of the amount of thermal energy required to raise the temperature and so dependent on the rate of heating (Figure S5, Supplementary Materials). A higher melting temperature of the combination CELL/PCL/KER versus both PCL alone and in the CELL/PCL blend is mostly influenced by the presence of cellulose, while the secondary structures within the keratin contribute to the amorphous regions [27]. The following presented results revealed that the studied biocomposite films have different fine structures, which, together with the different miscibility of the three biopolymers and their inter-and intramolecular interactions, represent essential factors affecting the film mechanical properties, such as tensile strength, modulus of elasticity, and breaking strain, which are presented in Table 4 and Figure 11.…”