MWCNTwith (95% purity, 30-50 nm outside diameter, and 10-20 μm length) were purchased from US Research Nanomaterials, Inc. USA. Nitric acid (70 wt.%) was obtained from (CARLO ERBA, France). Sulfuric acid (98 wt.%), Anhydrous 1 ml oxalyl chloride was added drop-wise to the suspension under nitrogen gas. This mixture was stirred at 350 rpm in an ice bath for 2 hours, then it was stirred at room temperature for another 2 hours, followed by overnight stirring at 70°C to remove excess oxalyl chloride.
After that, a mixture composed of 490 mg of low molecular weight chitosan and 40 ml of DMF was sonicated for 20 minutes, then added to the previous mixture (MWCNT, DMF, and oxalyl chloride) and stirred for 48 hours at 110°C. The resulting mixture was then filtrated and washed until no chitosan residues remained in the filtrate; finally, the particles were vacuum dried for 4 hours [28] .
After that, a mixture composed of 490 mg of low molecular weight chitosan and 40 ml of DMF was sonicated for 20 minutes, then added to the previous mixture (MWCNT, DMF, and oxalyl chloride) and stirred for 48 hours at 110°C. The resulting mixture was then filtrated and washed until no chitosan residues remained in the filtrate; finally, the particles were vacuum dried for 4 hours [28] .
