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 (1H and 13C NMR) and 2D NMR (1H–13C HSQC and HMBC) spectra provided the evidence of the occurrence of ROGP reaction. 1H–1H 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 C2 and C3 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.