Binding cellulose and chitosan via click chemistry: Synthesis, characterization, and formation of some hollow tubes

Abstract

A novel cellulose-click-chitosan polymer was prepared successfully in three steps: (1) propargyl cellulose with degrees of substitution (DS) from 0.25 to 1.24 was synthesized by etherification of bamboo Phyllostachys bambusoide cellulose with propargyl chloride in DMA/LiCl in the presence of NaH. The regioselectivity of propargylation on anhydrous glucose unit determined by GC-MS was in the order of 2 >> 6 > 3; (2) the functional azide groups were introduced onto the chitosan chains by reacting chitosan with 4-azidobenzoic acid in [Amim]Cl/DMF and the DS ranged from 0.02 to 0.46; (3) thus, the cellulose-click-chitosan polymer was obtained via click reaction, that is, the Cu(I)-catalyzed Huisgen 1,3-dipolar cycloaddition reaction, between the terminal alkyne groups of cellulose and the azide groups on the chitosan backbone at room temperature. The successful binding of cellulose and chitosan was confirmed and characterized by FTIR and CP/MAS 13C NMR spectroscopy. TGA analyses indicated that the cellulose-click-chitosan polymer had a higher thermal stability than that of cellulose and chitosan as well as cellulose-chitosan complex. More interestingly, some hollow tubes with near millimeter length were also observed by SEM. © 2012 Wiley Periodicals, Inc.