(384h) Surface-Modified Microfibrillated Cellulose to Enable Hydration and Dehydration

Rheological modifiers adjust flow behavior, control rheology and induce phase transitions in formulations. Our research aims to repurpose microfibrillated cellulose (MFC) from paper waste as a rheological modifier in personal, cosmetics, fabric and home care products formulations. MFC fibers have high aspect ratios, which alters rheology with minimal added material but can associate even at low concentrations. To maintain fiber dimensions and stability, MFC is produced and stored as an aqueous dispersion. This high-water content presents challenges for large-scale application by increasing transportation costs and environmental impact. Designing formulations that allow water removal before shipping and rehydration at the point of use is a more efficient and sustainable solution. Drying bare MFC leads to irreversible aggregation due to strong hydrogen bonding, causing loss of nanoscale structure and mechanical properties. Once fibers irreversibly aggregate, redispersion is difficult and negates the benefits of the nanoscale dimensions and high elastic moduli of a well-dispersed fiber network. To overcome these limitations, we modify MFC surface chemistry by synthesizing surface-oxidized MFC (OMFC) and grafting a thermoresponsive polymer, Jeffamine M2005 polyetheramine, onto the surface to enable dehydration and rehydration while retaining material properties. Both OMFC and thermoresponsive MFC are dried using lyophilization (freeze-drying), vacuum drying, and oven drying. We measure equilibrated rheological properties before and after a dehydration–redispersion cycle using amplitude and frequency sweeps and measure temperature-dependent rheology of thermoresponsive MFC. By modifying MFC surface chemistry and partially blocking hydroxyl groups, we can successfully redisperse MFC. We measure similar equilibrated material properties and thermal responsiveness in thermoresponsive MFC. This work provides a strategy to design MFC for cost-efficient shipping while preserving structure and properties through dehydration, transport, and rehydration.