Biobased materials, in particular cellulose nanocrystals (CNCs), show promise in applications such as oil and gas extraction fluids, cosmetics, pharmaceuticals and nanocomposites in which synthetic components are traditionally used. However, due to their incompatibility with non-polar environments, surface modification methods to tailor CNC properties are often required to maximize their potential in functional materials. Modification methods to tune the hydrophobicity, colloidal stability, thermal stability, or rheological properties of CNCs have been developed. Nevertheless, many require the use of harsh chemicals, complex chemistries and tedious clean up. Presented here, is an in-situ modification method to tune CNC properties through the precipitation of oligosaccharides. Oligosaccharides are small chain sugars formed as by-products during the production of CNCs. Within a specific range of degree of polymerization, oligosaccharides are selectively soluble in highly acidic environments but precipitate in more neutral conditions. Utilizing this selective solubility, we demonstrate a modification method to alter the surface charge, colloidal stability, and rheological properties of CNCs. Elemental analysis, conductometric titrations, zeta potential and gel permeation chromatography were used confirm successful CNC modification. Whereas thermogravimetric analysis, rheology and quartz crystal microgravimetry were used to assess the effects of surface oligosaccharides on CNC performance and processability. The in-situ nature of this modification method would allow it to be easily implemented in CNC manufacturing facilities, without alterations to existing production lines. As such, it provides a simple and green alternative for CNC surface modification as it requires only those processes already available in their industrial production.

Developing an in-situ oligosaccharide surface modification of cellulose nanocrystals

ACS Spring Meeting 2021

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