Towards thermoplastic hemicellulose: Chemistry and characteristics of poly-(ε-caprolactone) grafting onto hemicellulose backbones

Hemicellulose is a highly available polysaccharide but with poor industrial applications attributed mainly to difficulties in processability, owing to extensive intermolecular hydrogen bonds. In the current study, hemicellulose was subjected to a chemical modification by ring-opening graft polymerization of ε-caprolactone (CL) to improve its processability for value-added applications. Hemicellulose-graft-poly-(ε-caprolactone) (HCgPCL) copolymers were synthesized using 1,5,7-triazabicyclodecene [4.4.0] (TBD) as an organic catalyst. The extent and length of grafted PCL sidechains in HCgPCL copolymers were controlled by adjusting the molar ratios of CL monomer to anhydroxylose residues. The various characterization analysis of the physicochemical and mechanical properties of HCgPCL materials revealed a successful grafting. The NMR analyses indicated that the degree of polymerization (DP) of the grafted PCL can range between 1.82 and 4.26 based on the changes in the molar ratio of the reactants. Furthermore, results indicated that the mechanical and the hydrophobic properties of the materials were enhanced by PCL grafting onto hemicellulose. Finally, biodegradability measurements indicated a remarkable (95.3–99.7%) materials biodegradation. We anticipate that the HCgPCL copolymers will have great potential to be an eco-friendly part of the bioplastic industry.