Synthesis and Characterization of Xylan Grafted with Polyethylene Glycol in Ionic Liquid and Their Use as Moisture-Absorption/Retention Biomaterials

The objective of this study is to broaden the application of xylan as moisture‐absorption/retention biomaterials by grafting polyethylene glycol (PEG) on xylan backbone. Ionic liquid 1‐allyl‐3‐methylimidazolium chloride ([Amim]Cl) and 4,4‐diphenylmethane diisocyanate are used as reaction media and coupling reagent, respectively. FT‐IR, 1H‐NMR, and gel permeation chromatography analyses indicate the successful occurrence of the grafting reaction. Thermogravimetric analysis/derivative thermogravimetry indicates that the thermal stability of xylan increases after the grafting of the PEG side chains. With an increase of the degree of substitution of xylan‐g‐PEG, the molecular weight (Mw) of PEG side chains (1000 and 5000 g mol−1), and the relative humidity of environment, the moisture‐absorption/retention ratio of xylan‐g‐PEG increases. To evaluate the biodegradability/biocompatibility of this promising material, the ratio of biochemical oxygen demand to chemical oxygen demand of xylan‐g‐PEG and the cytotoxicity are tested on the samples. The results indicate that PEG‐modified xylan has great potential as moisture‐absorption/retention biomaterials. Xylan‐graft‐PEG, as a biodegradable moisture‐absorption/retention material, is prepared in [Amim]Cl with 4,4‐diphenylmethane diisocyanate coupling agent. The maximum moisture‐absorption/retention ratio of xylan‐graft‐PEG at RH 81 and 43% after 96 h is ≈ 39%/47% and 37%/43%, respectively. The biodegradability and cytotoxicity studies illustrate the possibility of applying xylan‐graft‐PEG as environmentally friendly moisture‐absorption/retention biomaterial.