Functionalized celluloses and their nanoparticles: Morphology, thermal properties, and solubility studies

• First detailed work-up procedure for preparing spherical shaped nanoparticles of carboxy functionalized cellulose.
• Thermal stability and morphologies showed progressive oxidation produced non-nano fibrils and spherical nanoparticles.
• Only at ∼14% oxidation DTG showed 3 peaks, due to the glucuronic moiety appearing separately from the amorphous and crystalline peaks.
• Improved solubility of the functionalized celluloses and their nanoparticles observed, enabling further applications.

Agricultural residues derived cellulose was used to synthesize a new series of carboxy functionalized cellulosic nanoparticles (quasi-spherical shaped, 13.2–21.5% carboxyl content) and macro-sized 6-carboxycelluloses (long-fibril shaped, 1.7–22% carboxyl content). The DP (50–70) and yield (upto 46%) of nanoparticles were manipulated by controlling the reaction temperature and time. TGA/DTG thermographs of the carboxycelluloses gave thermostability data and co-related well with the residual crystalline, amorphous, and anhydroglucuronic acid content. The particle shape and size had no effect on the thermal stability. Some derivatives were fully or partially soluble in aqueous alkali and non-aqueous solvents, which can lead to increased versatility of these polymers.