Despite their numerous properties such as renewability, high specific surface area (~200-300 m<sup>2</sup>/g), excellent mechanical properties (Young’s modulus ~150 GPa), liquid-crystalline self-organization ability, light weight, or non-toxicity, cellulose nanocrystals (CNCs) still require a fine tuning of their surface properties to be used as building blocks for materials with advanced functionalities. In this framework, thermosensitive polyetheramines were successfully grafted onto the surface of CNCs using a peptidic coupling reaction after TEMPO oxidation. This synthetic strategy combines several advantages since it is carried out in aqueous medium under ambient conditions and because the amide bond that form can easily be characterized by spectroscopic techniques. The properties of such thermosensitive polymer-grafted CNCs (TP-CNCs) have been characterized by dynamic light scattering (DLS), small angle neutron scattering, electron microscopy and rheology. When dilute suspensions are considered, a highly repeatable and reversible aggregation/redispersion behavior is observed. Interestingly, results show that TP-CNCs assembly upon temperature increase depends on the pH and ionic strength of the suspensions. Actually, measurements reveal that the electrosteric nature of the interaction forces make the TP-CNCs temperature-, pH and salt-sensitive. When more concentrated suspensions are used, a viscous liquid / elastic solid transition is observed when the temperature is increased beyond the polymer cloud point due to larger aggregates formation and physical crosslinking. Such a multisensitive behavior of polymer-grafted CNCs make them suitable for the development of biobased materials with advanced functional properties.<br/>

Multiresponsive polymer-grafted cellulose nanocrystals

249th National Meeting (2015)

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