By learning from nature and using bio-based components, we can engineer sustainable high-performance materials with improved functionality. Cellulose nanocrystals (CNCs) are biocompatible and renewable nanoparticles which have an intermediate hydrophilicity, high mechanical strength and a large aspect ratio. This work explores using responsive CNCs as flocculants, rheological modifiers and emulsion stabilizers. To impart responsive behavior, CNCs were surface-modified using polymer “grafting-from” or polymer adsorption methods; all reactions are one-step and water-based with the goal of developing industrial feasible modification routes and applications.<br/><br/>In the first example, CNCs were functionalized using “grafting-from” free radical polymerization in water with either 4-vinyl pyridine or N-isopropyl acrylamide monomers, using ceric ammonium nitrate as the initiator. The resulting pH and temperature responsive CNCs have potential as flocculants and rheological modifiers in a variety of products. Secondly, the temperature responsive polymer methylcellulose (MC) was physical adsorbed to CNCs which improve the surface activity and wettability of CNCs. MC-coated CNCs can stabilize oil-in-water emulsions and when excess MC is added, thermoresponsive “emulsion gels” arise. The emulsions are extremely stable over long time periods (&gt; 1 year) and multiple heat-cool cycles and the droplet size can be tailored by varying the ratio of polymer to cellulose. These emulsions can further be dried to give “oil powders” which are redispersible and may have applications in food, cosmetic and pharmaceutical formulations.

Responsive and “switchable” cellulose nanocrystal hybrid materials

251st National Meeting (2016)

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