This presentation aims to provide an overview of nanocellulose-based functional materials of detecting color change in response to pH. Methods of isolating nanocelluloses such as acid hydrolysis or ammonium persulfate (APS) oxidation, and TEMPO-oxidation are employed to obtain cellulose nanocrystals (CNCs), or cellulose nanofibrils (CNFs), respectively. The surfaces of these nanocelluloses were modified to build chemical bonds with pH-indicators such as bromocresol green (BCG), bromocresol purple (BCP) or neutral red (NR) that had been activated prior to its reaction. Chemical reactions between these nanocellulose and pH-indicator were also characterized with various methods. Composites of nanocellulose/pH-indicator were incorporated into polymer matrix to prepare pH-sensitive color-changing films. In addition, CNF-based hydrogels impregnated with anthocyanin are also tested for detecting color change. These films are tested for pH or color change to develop nanocelluose-based functional materials, including color reversibility, leaching resistance, and mechanical properties. These results suggest that the nanocellulose/pH-indictor composites have a great potential as functional indicator films of detecting color change in response to pH during the storage of food.

Nanocellulose-based functional materials of detecting color change in response to pH

ACS Spring 2022

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