Tailoring physicochemical properties of collagen-based composites with ionic liquids and wool for advanced applications

Wool, choline dihydrogen phosphate ([Ch][DHP]) or choline serinate ([Ch][Seri) ionic liquids (ILs) were incorporated into native collagen formulations and films were prepared by compression molding. Scanning electron microscopy (SEM) images showed no agglomeration, indicating good dispersion of additives within films. The denaturation peak observed by differential scanning calorimetry (DSC), along with infrared spectroscopy (FTIR) results, showed that collagen fibrillary structure was preserved in all samples. These outcomes were correlated with X-ray diffraction (XRD) patterns. Wool or ILs addition increased tensile strength and improved electrical conductivity and all films showed antistatic behaviour. The samples showed a high dielectric constant, mainly determined by mobile charge contributions. This work shows the potential of native collagen films with tuneable physical-chemical characteristics for a new generation of sustainable materials for a wide variety of applications.This research was funded by MCI/AEI/FEDER, UE, grant number RTI2018-097100-B-C22. This work was also supported by the Portuguese Foundation for Science and Technology (FCT) under strategic funding UIDB/04650/2020, UID/FIS/04650/2021, project PTDC/FIS-MAC/28157/2017, grant SFRH/BPD/121526/2016 (D.M.C) and Investigator FCT Contract 2020.04028.CEECIND (C.M.C.) funded by national funds through FCT and by the ERDF through the COMPETE2020-Programa Operacional Competitividade e Internacionalização (POCI). The authors also acknowledge funding from the Basque Government (KK-2021/00131). Mireia Andonegi also thanks the Basque Government for her fellowship (PRE_2017_1_0025). Thanks are also due to the Advanced Research Facilities (SGIker) from the UPV/EHU. Finally, the authors would like to thank Paula Menoyo for the wool provided