A Facile Microwave Assisted TEMPO/NaOCl/Oxone (KHSO5) Mediated Micron Cellulose Oxidation Procedure: Preparation of Two Nano TEMPO‐Cellulose Forms

An efficient and rapid method is established for micron cellulose (1, 20 microns) oxidation utilizing Oxone (KHSO5) in combination with 2,2,6,6‐tetramethylpiperidinyl‐1‐oxyl (TEMPO) and NaOCl in aqueous NaHCO3 solution (pH 7.5 to 8.5) under microwave irradiation. This method affords two different forms of nano TEMPO‐cellulose, that is, a water‐insoluble form (Form‐I, 14 nm) and a water‐soluble form (Form‐II, 8 nm). Cellulose oxidation utilizing this Oxone methodology has advantages over other methodologies, which include low cost and formation of two nano TEMPO‐cellulose forms over a rapid reaction time utilizing microwave irradiation conditions. TEMPO‐cellulose forms are characterized by FT‐IR, NMR, solid state 13C‐NMR, and by elemental analysis. The TEMPO‐cellulose forms morphology is studied by scanning electron microscopy analysis. The average fiber width and length of TEMPO‐cellulose materials are determined in nanometer range by transmission electron microscopy analysis and the surface charge is identified by zeta potential. A rapid and efficient micron cellulose oxidation procedure is successfully developed by utilizing 2,2,6,6‐tetramethyl piperidinyl‐1‐oxyl (TEMPO), NaOCl, and Oxone (KHSO5), in aqueous NaHCO3 solution under microwave irradiation to afford two fully characterized nano TEMPO‐cellulose forms. This methodology is efficient and environmentally safe, and avoids the formation of undesirable aldehyde intermediates as by‐products, and the depolymerization of cellulose chains caused by β‐elimination.