Structural and sorption properties of bio-nanocomposite films based on κ-carrageenan and cellulose nanocrystals

There is an increased interest on changing the synthetic based materials to biodegradable ones, especially with natural polymers, polysaccharides or proteins. In this research we prepared bio-nanocomposite formulations with different component concentrations and investigated their structural features, with focus on the interactions, sorption properties, and how the combination between them influences these properties. By infrared spectroscopy, principal component analysis (PCA) and two-dimensional correlation spectroscopy (2DCOS) was identified that in the blending process are involved the -SO4 and C(4)-O-S groups of beta-d-galactose, C-O groups, (O=S=O) of carrageenan and -OH and C-O groups from CNCs. The water uptake and water sorption properties decrease with increasing the CNCs content in the formulations from about 15% for kappa to 10% for kappa C15 and from about 128% for kappa to 115% for kappa C15, respectively. The increase of the CNCs content induced an increase of the water contact angle from 47 for kappa to 90 for kappa C15, indicating once again the involvement of the free hydroxyl groups in the hydrogen bonded interactions. (C) 2019 Elsevier B.V. All rights reserved.