Properties of cellulose nanocrystals (CNCs), prepared by the sulfuric acid hydrolysis of natural cellulose fibers, depend on their dimensions, and also on their surface charge, which results primarily from sulfate half-ester groups introduced on the nanocrystal surface during acid treatment. The surface charge and surface sulfur content are key to the colloidal properties of CNC, and are usually inferred from conductometric titration. The titration requires the exhaustive removal of free acid by dialysis, and is sometimes combined with treatment with ion exchange resins. Extensive dialysis effectively removes free acid, but similar results are also achieved by membrane ultrafiltration. However, the use of ion-exchange resins can lead to inaccurate estimates of sulfur content. Sulfur contents measured by conductometric titration and by elemental analysis agree when thoroughly purified, well-dispersed samples and appropriate resin treatments are used.

Estimation of the surface sulfur content of cellulose nanocrystals prepared by sulfuric acid hydrolysis

245th National Meeting (2013)

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