Résumé
Although quite abundant, feruloylated arabinoxylans are poorly valued today. They are water soluble and lead to covalent hydrogels simply by oxidation of the ferulic moieties 1. These macroporous hydrogels, with mesh sizes ranging from 40 to 400 nm, are stable whatever the pH and ionic strength, and can absorb up to 150 grams of water per gram of polymer. While their structure and swelling capacity make them good candidates as encapsulation matrices 2, their mechanical strength (elastic modulus of the order of 100 Pa) needs to be improved to extend their use as materials.The study investigates the enhancement of viscoelastic properties in feruloylated arabinoxylan (F-WEAX) hydrogels by incorporating cellulose nanocrystals (CNC). F-WEAX, a cereal cell wall polysaccharide, was crosslinked using laccase in the presence of CNC, with CNC/F-WEAX weight ratios ranging from 0 to 1.5. The addition of CNC significantly increased gel stiffness, with the elastic modulus scaling as [CNC]³. CNC also influenced relaxation behavior, enhancing the loss factor at low frequencies.Quartz crystal microbalance with dissipation (QCM-D) measurements showed that F-WEAX adsorbed irreversibly onto CNC, similar to non-feruloylated arabinoxylans. In the presence of CNC, laccase action led to twice as many elastically active oxidation products, namely dimer and trimer forms of ferulic acid (FA). Consequently, the swelling capacity of F-WEAX-CNC gels decreased but less than expected from the increase in shear modulus. This synergistic enhancement of elasticity while maintaining swelling capacity is attributed to the formation of high-functionality junctions through the irreversible adsorption of F-WEAX onto CNC.The study concludes that the introduction of CNC prior to F-WEAX gelation significantly improves elastic properties more effectively than increasing F-WEAX concentration alone. This is due to the high affinity of F-WEAX for CNC, increased cross-link density, and the formation of multi-armed junctions. The findings highlight the potential of CNC in enhancing the mechanical properties of biopolymer hydrogels, which can be achieved through simple mixing. (1) Izydorczyk, M.; Biliaderis, C.; Bushuk, W. Journal of Cereal Science 1990, 11 (2), 153-169.(2) Paz‐Samaniego, R.; Rascón‐Chu, A.; Brown‐Bojorquez, F.; Carvajal‐Millan, E.; Pedroza‐Montero, M.; Silva‐Campa, E.; Sotelo‐Cruz, N.; López‐Franco, Y. L.; Lizardi‐Mendoza, J. Journal of Applied Polymer Science 2018, 135 (26).