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High strength and self-healing properties of hydrogels are of great interest in tissue engineering and biomedical fields. In this paper, nanocomposite hydrogels were prepared by freeze-thaw cycle method via fabricating physical cross-links into chemical-crosslinked formed polymer network. The properties of nanocomposite hydrogels were characterized by FTIR, XRD, SEM, rheological analysis, swelling analysis and mechanical test. The results showed that the electrostatic interaction between CNC and QAX and the high amount of PVA (20 wt%) were favorable to improve the mechanical properties of nanocomposite hydrogels, in which the maximum compressive strength and elongation at break of nanocomposite hydrogels were 1.56 MPa and 771 %, respectively. Prepared hydrogels achieved self-healing without any external stimuli at room temperature with the help of hydrogen bonds and the entanglement of long polymer chains, the healing efficiency was 37.03 % within 48 h. These hydrogels with high strength and self-healing properties will offer new insights for xylan application., Competing Interests: Declaration of Competing Interest The authors declare no conflict interest., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

In this study, nanocrystalline cellulose (NCC) resulting from sulfuric acid hydrolysis of wood cellulose fiber, was rendered cationic by grafting with glycidyltrimethylammonium chloride (GTMAC). An optimization of the reaction parameters, such as water content, reactant mole ratio, and reaction media was performed. The presence of cationic GTMAC on the surface of NCC was confirmed by Fourier Transform Infrared Spectroscopy (FTIR). The cationically modified NCC was characterized by surface charge density, degree of substitution, ζ potential, and particle size. It was found that the cationic surface charge density of NCC can be increased by controlling the water content of the reaction system. Surface cationization of NCC led to an increase in the surface charge density over the un-modified NCC. The cationically modified NCC was well dispersed and stable in aqueous media due to enhanced cationic surface charge density. Transmission electron microscopy (TEM) images showed the improvement in state of dispersion of cationically modified NCC over the un-modified NCC. The optimum water content was found to be 36 wt% for aqueous based media and 0.5 water to DMSO volume ratio for aqueous-organic solvent reaction media. The increased surface charge density of NCC also delayed the onset of gelation in aqueous system., (Copyright © 2012 Elsevier Ltd. All rights reserved.)