Cellulose nanocrystals (CNC) are readily dispersible only in very hydrophilic environments, such as aqueous media and very polar solvents. Different approaches have been attempted to alter/improve the surface properties and dispersibility of CNC in organic solvents (hydrophobic media), including functionalization with small molecules and grafting of polymer chains to the CNC surface. However, when hydrophobic polymer chains are grafted on the CNC surface, CNC are irreversibly altered toward increased hydrophobicity, which can be undesirable for some applications. Grafting stimuli-responsive polymers chains to the CNC surface may offer a solution to this problem, and surface-initiated nitroxide mediated polymerization represents a very versatile and robust technique to perform grafting polymerization on the CNC surface. In this study we present stimuli-responsive CNC whose surface properties can be reversibly switched using only carbon dioxide (CO2) and nitrogen as triggers to conduct the switching process. In recent years carbon dioxide has emerged as a new and innovative “trigger” for stimuli-responsive materials. In addition to being abundant, inexpensive, nontoxic and environmentally benign, CO2 does not accumulate in a system upon repeated cycles. Among the new CO2-switchable materials that have been developed, polymer-based materials are of particular interest. The change in properties result due to a transition from a neutral to charged state (or vice versa) on functional groups within the polymer (e.g. amidines or tertiary amines). The modification of CNC surfaces was performed using different CO2-responsive polymer chains will be presented.

Graft modification of cellulose nanocrystals with carbon dioxide responsive polymers via living radical polymerization

253rd National Meeting (2017)

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