Cellulose, the most abundant and renewable biopolymer on Earth, holds immense potential as a sustainable alternative to fossil-based feedstocks due to its biodegradability and wide availability. Among its derivatives, cellulose nanocrystals (CNCs) stand out for their exceptional mechanical properties and versatile applications in functional materials, including nanocomposites, films, and biomedical devices [1]. However, conventional cellulose modification techniques often require toxic solvents, harsh reaction conditions, or dissolution of cellulose, compromising its crystalline structure and mechanical properties [2]. Alternatively, mechanochemistry – solid-state synthetic approach and accelerated aging enable transformations of insoluble reactants without dissolution or the use of caustic solvents, offering faster reaction rates through high reactant concentrations [3].
We recently reported a solvent-free mechanochemical method for tosylation and subsequent nucleophilic substitution of cellulose nanocrystals (CNCs) with amines and esters, achieving efficient modification while preserving CNC morphology and crystallinity. By optimizing key reaction parameters such as milling time, base type, and reagent amounts, the approach enabled fast and sustainable functionalization of CNCs without excessive solvent use [4]. As a continuation of this work, we are currently expanding the method to adapt it for other amine-functionalized nanocelluloses [Fig-1]. These newly adapted and nucleophilically substituted materials could create a platform for developing versatile hierarchically porous materials. We will investigate the conditions of ball-milling and accelerated aging to control regioselectivity (targeting the 6-OH position) and achieve a high degree of nucleophilic substitution while maintaining the crystalline structure of the nanocellulose. Key analytical techniques will include elemental analysis, in-solution cellulose NMR, Powder X-Ray Diffraction (XRD), and Transmission Electron Microscopy (TEM). A schematic representation of the research overview is shown in Figure 1.