Cationized Cellulose Materials: Enhancing Surface Adsorption Properties Towards Synthetic and Natural Dyes

Cellulose is a homopolymer composed of β-glucose units linked by 1,4-beta linkages in a linear arrangement, providing its structure with intermolecular H-bonding networking and crystallinity. The participation of hydroxy groups in the H-bonding network results in a low-to-average nucleophilicity of cellulose, which is insufficient for executing a nucleophilic reaction. Importantly, as a polyhydroxy biopolymer, cellulose has a high proportion of hydroxy groups in secondary and primary forms, providing it with limited aqueous solubility, highly dependent on its form, size, and other materialistic properties. Therefore, cellulose materials are generally known for their low reactivity and limited aqueous solubility and usually undergo aqueous medium-assisted pretreatment methods. The cationization of cellulose materials is one such example of pretreatment, which introduces a positive charge over its surface, improving its accessibility towards anionic group-containing molecules or application-targeted functionalization. The chemistry of cationization of cellulose has been widely explored, leading to the development of various building blocks for different material-based applications. Specifically, in coloration applications, cationized cellulose materials have been extensively studied, as the dyeing process benefits from the enhanced ionic interactions with anionic groups (such as sulfate, carboxylic groups, or phenolic groups), minimizing/eliminating the need for chemical auxiliaries. This study provides insights into the chemistry of cellulose cationization, which can benefit the material, polymer, textile, and color chemist. This paper deals with the chemistry information of cationization and how it enhances the reactivity of cellulose fibers towards its processing.