Tosylation of Cellulose Nanowhisker in Aqueous Solution

Natural polymers such as cellulose can be employed to hydrolyze the amorphous region of the polymer. The uses of polysaccharide nanoparticles are receiving a significant amount of attention because of their nontoxicity. This propertie make them excellent candidates for implant materials and drug carriers. The work presented here involves the chemical modification of cellulose nanowhisker with poly (ethylene imine). the cellulose used in this study was cotton linters with degree of polymerization of 850.Briefly Cellulose nano crystals were prepared through dissolution of cellulose in NaOH/Urea then in sulfuric acid aqueous solutions [1], [2], [3] and then were tosylated by p-toluenesulfonyl chloride. 0.5 gr tosylated cellulose Nanowhisker was used as macro initiator and placed in reaction tube then 2-ethyl-2-oxazoline added under nitrogen atmosphere and kept at 90 oC for 50h, resulted (CNW-g-PEOX) was washed with methanol. Finally CNW-g-PEOX was hydrolyzed in %10 solution of NaOH at 98 oC for 3h.The nano crystalline cellulose are found embedded in the depth of lignocellulosic matrix enclosed by less ordered amorphous regions which can be removed after different chemical and physical treatments. AFM photograph of CNW s are shown in Figure 1. After the acid-treatment process, cellulose has been destructed to be nanowhiskers with a size range of 30–80 nm. Resulted CNW s were grafted by PEOX and then PEOX moiety in graft copolymer was hydrolyzed to PEI. The structure of products was confirmed by FTIR and 1H NMR spectroscopes. the 1H NMR spectra of CNW-g-PEI shows characteristic absorption for cellulose (3-5 ppm) and PEI peaks (3.4 ppm). Also the crystallinestructure and thermal properties of modified cellulose nanowhiskers were studied using DSC and XRD. The collected data showed that crystalline structure of cellulosenanowhiskers have not changed during chemical modification reaction. Successful surface modification was confirmed using FTIR and NMR spectroscopy and also DSC and XRD techniques. The described surface modification clearly changes the character of the nanocrystal surfaces as a cationic graft polymer. These modified nanocrystals will be tested as nonviral vectors for gen delivery systems