Integration of graft copolymerization and ring-opening reaction: A mild and effective preparation strategy for “clickable” cellulose fibers

A mild and effective strategy to prepare alkynyl-functionalized cellulose fibers (A-CFs) and azido-functionalized cellulose fibers (N3-CFs) was presented. Epoxy-cellulose fibers (Epoxy-CFs), graft copolymerization products of cellulose fibers (CFs) and glycidyl methacrylate (GMA), were prepared using cerium ammonium nitrate (CAN) as initiator. Epoxy groups content of Epoxy-CFs were as high as 2.5 mmol/g. Introduction of alkynyl/azido groups into Epoxy-CFs were achieved through ring-opening reactions of epoxy groups with propargylamine (PgAm) and sodium azide (NaN3), respectively. Under appropriate conditions, A-CFs with alkynyl groups of 0.57 mmol/g and N3-CFs with azido groups of 0.35 mmol/g were obtained. Click reactivities of A-CFs, N3-CFs and Epoxy-CFs were verified by Cu(I) catalyzed alkyne-azido cycloaddition (CuAAC) and thiol-epoxy click reactions. A-CFs, N3-CFs, Epoxy-CFs and their clicked products were characterized by attenuated total reflectance Fourier-transform infrared spectroscopy (ATR-FTIR) and X-ray photoelectron spectroscopy (XPS).