Plant components are an inexhaustible source for the construction of bio-based materials. Here we report, for the first time, the elaboration of biobased cellulose nanocrystals (CNC)/xyloglucan (XG) hydrogels. XG is a hemicellulose displaying a great affinity for cellulose surface and can be thus irreversibly adsorbed on CNC. Properties of the hydrogels were investigated by varying the molar mass of XG either by enzymatic treatment with Endoglucanase (EG2) or physical fractionation by ultrasound (US). Fractions were characterised by high-performance size exclusion chromatography (HPSEC) and their monosacchari decompositions were determined. Three fractions with high, average and small molar mass, (800, 300 and 100 103 g/mol respectively), were selected in order to tune the properties of the hydrogel. Sol-gel transition conditions were determined for each fraction by achieving phase diagram using the inverted tube method. Mechanical properties, assessed by rheology, are improved by increasing XG molar mass since elastic modulus is higher for hydrogels formed with higher molar mass fractions as well as the strain at break. Gel formation is likely due to the adsorption of XG fractions on CNC which increases the effective hydrodynamic volume of CNC leading to steric stabilization and interactions between loops and tails of XG adsorbed.

Cellulose nanocrystals; xyloglucan fractions; rheology; hydrogels