Characterization of Xylan-graft-Polycaprolactone Copolymers Prepared in Ionic Liquid

In this study, xylan- graft -polycaprolactone (xylan- g -PCL) with different degrees of substitution (DS) and degrees of polymerization (DP) were prepared by homogeneous ring-opening graft polymerization (ROGP) of ε-caprolactone (ε-CL) onto xylan in ionic liquid (IL) 1-allyl-3-methylimidazolium chloride ([Amim]Cl) using 4-dimethylaminopyridine (DMAP) as catalyst. FT-IR, 1D ( 1 H and 13 C NMR) and 2D NMR ( 1 H– 13 C HSQC and HMBC) spectra provided the evidence of the occurrence of ROGP reaction. 1 H– 1 H COSY confirmed the correct assignment of the proton signals. HSQC also indicated that 38.78% and 61.22% of PCL side chains were attached to C 2 and C 3 positions of anhydroxylose units, respectively. Xylan- g -PCL copolymers were further characterized by TGA/DTG, SEM, and XRD. The results indicated that the thermal stability of xylan increased upon the DMAP-catalyzed ROGP reaction in [Amim]Cl, and the surface morphologies were significantly changed with increased DS.