Photoluminescence Control of Cellulose via Surface Functionalization Using Oxidative Polymerization.

Control of the photoluminescence properties of cellulose is conducted by introduction of conducting polymers including fluorene (F) and 3-hexylthiophene (3HT) on cellulose surface through FeCl3 oxidative polymerization. The UV-vis absorption peak of cellulose grafted with the 3-hexylthiophene and fluorene copolymer was increasingly blue-shifted with increasing fluorene content and the shift in the peak position in photoluminescence spectra depend on the initial 3HT:F ratio of the copolymer. The crystallinity and thermal stability of cellulose decreased slightly upon graft polymerization with PF and P3HT, while the quantum yield, determined using absolute methods, increased from 3.1 to 9.7% with increasing fluorene content. The roles of the 3HT and F copolymers in improving the properties of cellulose were thoroughly studied by FT-IR, UV-vis, fluorescence, X-ray diffraction (XRD), thermogravimetric (TG), transmission electron microscopy-energy dispersive X-ray (TEM-EDX), and quantum yield measurements. Mechanistic insight into the grafting reaction is also provided.