Deodorant Processing for Cotton Fabrics Using Cellulose Nanocrystals

In this study, cellulose nanocrystals (CNC), characterized by ultrafine natural fibers measuring several tens of nanometers in width and shorter fiber length compared to cellulose nanofibers (CNF), were incorporated into cotton fabrics through impregnation. Subsequently, functional processing was performed without inducing changes in the physical properties and appearance of the fabric. Moreover, by removing the CNCs from the cotton fabric through washing and applying new CNCs, it is expected that the functionality can be reinstated without damaging the cotton fabric. We aimed to propose a method for functional processing of recyclable cotton fabrics using CNCs. The oxidized CNC-processed fabric demonstrated excellent deodorizing performance for ammonia without manifesting significant changes in physical properties when the CNCs were introduced through impregnation. Although the oxidized CNC-processed fabric with a large amount of CNC adsorption had a high bending rigidity, the ventilation resistance remained unchanged, preserving the characteristic air permeability inherent to cotton fabric. In terms of deodorizing performance, an elevated CNC absorption correlated with increased ammonia deodorizing efficacy attributed to the heightened carboxyl group content capable of capturing ammonia. Quantification of CNC adsorption amount and carboxyl group content on the fabric using toluidine blue O, a cationic dye, revealed that ammonia was adsorbed to approximately 55% of the carboxyl groups on the fabric. Upon subjecting the CNC-treated fabric to a mild washing regimen, it was observed that most of the CNCs detached after several cycles, and the deodorizing performance against ammonia was recovered upon reapplication of CNCs. Remarkably, the oxidized CNCs exhibited excellent deodorizing performance for ammonia and demonstrated their ability to be removed after multiple washing cycles. In the future, by using various chemically modified CNCs, we can expect to add several other functionalities to fabrics.